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A general high-efficiency time-modulated module and harmonic beam scanning time-modulated array (TMA) are proposed and investigated in this paper. By introducing the periodically controlled phased-shifters, a significant improvement on theoretical overall efficiency and transmitted bandwidth can be realized in harmonic beam scanning. Then equivalent cascade structure of the general modulation module is proposed for RF circuit simplification and practicability in actual applications. Theoretical derivation and simulation results show that increased efficiency, 100% feeding network efficiency and theoretical overall efficiency tending to 100% without consideration of insertion loss, can be achieved with the increase the phase-shifter states when only a single sideband is utilized. Compared to the existing state-of-the-art harmonic beam scanning TMAs, the proposed TMA exhibits a much higher overall efficiency while keeps a similar hardware complexity. Additionally, with acceptable increase of circuit complexity less than existing works, similar level of the wide transmission bandwidth can also be achieved. To experimentally verify the feasibility of the proposed general design, a 4-bit time-modulated module with reconfigurable states and the corresponding 8-element harmonic beam scanning TMA are fabricated and tested. The experiments on signal transmission and harmonic beam scanning demonstrate the effectiveness of power loss reduction and improvement in transmitted bandwidth with the increase of modulation phase states.

A highly integrated fundamentally operated direct-conversion quadrature (IQ) TX/RX chipset with a tunable carrier of 215-240 GHz for high-speed wireless communication is presented. The TX/RX front-ends are fabricated in the 0.13-μm SiGe HBT technology and combined with wire-bonded chip-on-board (COB) packaging for high-speed baseband (BB) signaling. For test purposes, the chipset features a dedicated dual-polarization architecture with a suitable on-chip antenna to allow controlled variation in I-to-Q channel leakage resulting from frequency-dependent upper sideband (USB)/lower sideband (LSB) asymmetry in the RF path of the jointly operated TX and RX and the corresponding analysis of its impact on system error vector magnitude (EVM) of the complete link. The analysis is aided by system-level BB-referred problem formulation with similarity to the classical IQ error in the local oscillator (LO) and BB paths. While operated in a loop-back configuration, the front-ends support the LO-dependent BB-referred channel bandwidth (BW) of 16-20 GHz at the board level with the typical free-space-related double sideband (DSB) Psat/OP1 of 7/3.5 dBm and single sideband (SSB) conversion gain (CG)/noise figure (NF) of 7.5/17.5 dB for the TX and RX, respectively. Under regular working conditions, data rates above 80 Gb/s are demonstrated for 16-quadrature amplitude modulation (QAM) modulation in a 0.6-m line-of-sight wireless characterization setup, with the maximum of 100 Gb/s at 225 GHz. The achievable speeds are limited by frequency-dependent USB/LSB asymmetry in the RF path resulting in systematic error vector floor independently of the underlying SNR and IQ error. With elimination of the asymmetry-incurred I-to-Q leakage from the RF path, the potential of increasing the data rates to at least 120-140 Gb/s is shown, indicating the severeness of this RF impairment for wide modulation bandwidth.

We propose and experimentally demonstrate a polarization-insensitive single sideband modulator based on silicon microring modulators (MRM). The proposed modulator splits and modulates the two orthogonal polarization states of an input laser in a loopback structure, with an on-chip silicon polarization splitter rotator (PSR), overcoming the polarization dependence of the silicon photonic modulator. The IQ configuration of the modulator enables single sideband modulation, thus improving the resistance of the modulated signal to chromatic dispersion and extending the transmission reach. The adoption of an MRM relieves the bandwidth limitation in polarization-diverse versions of SiP Mach-Zehnder modulators (MZM). Our experiments validate the proposed modulator polarization insensitivity and transmission performance.

Two structures that can realise optical single sideband modulation without generating both second order upper and lower sidebands are presented. They are based on a dual-parallel Mach Zehnder modulator (DP-MZM) with an optical filter and a dual-polarisation dual-parallel Mach Zehnder modulator (DPol-DPMZM) with a 90° hybrid coupler. The former is an all-optical structure and hence it has a very wide bandwidth. The latter uses one DP-MZM to realise single sideband suppressed carrier modulation while the other DP-MZM simply passes the optical carrier. It also suppresses the third order sideband on the same side as the wanted fundamental RF modulation sideband. Hence, in an ideal situation, there is no second order harmonic component generated after photodetection. Experimental results are presented for the novel structures, which demonstrate the realisation of optical single sideband modulation without second order sidebands. The results also show large fundamental to second order harmonic power ratio over a wide input RF signal frequency range even after inserting a long single mode fibre into the system for signal transmission. The new optical single sideband modulators find applications in improving the multioctave spurious free dynamic range in a long-haul fibre optic link and reducing measurement errors in an optical vector analyser.

Phase noise of PLLs is one of the critical issues in high-performance transceivers. Especially, in-band noise is troublesome because the phase noise inside a loop bandwidth is hard to be filtered out due to low-pass characteristic of most PLL components. The in-band noise of PLLs is mainly caused by charge-pumps (CPs), so that large-size transistors are used to improve in-band noise of CPs. Due to this trade-off between inband noise and occupied area, a large area is needed for CPs in high-performance transceivers. In this paper, we propose a noise-canceling CP to improve in-band noise. The prototype of the proposed CP embedded in a 28-GHz LC-PLL was fabricated using 16nm FinFET process and 1.2-dB improvement of single sideband (SSB) integrated phase noise is achieved. As the results of in-band noise improvement, occupied area for the CP can be reduced to 22%.

A photonics-based frequency mixer for up converting an IF signal into an RF signal with very large suppression in the carrier and the sideband is presented. The mixer is filter free and has a simple structure. It enables off-the-shelf bias controllers to be incorporated into the system. This solves the problem of the carrier and sideband suppression reduces with time that is present in all reported photonics-based single sideband mixers. Experiments are conducted to verify the proposed mixer structure. Results show the single sideband mixer generates an up converted RF signal with more than 40 dB suppression in the carrier and sideband over a wide frequency range. This is a 10-dB improvement compared to the reported structures. A conversion efficiency of around -6 dB is attained, which is over 10 dB higher than the reported structures. Frequency up conversion of an IF signal with a band of frequency and a long-term stable performance are also demonstrated.

This report presents a down-conversion method involving digital sideband separation for the Yuan Tseh Lee Array to double the processing bandwidth. The receiver consists of a MMIC HEMT LNA frontend operating at a wavelength of 3 mm, and sub-harmonic mixers that output signals at intermediate frequencies of 2 - 18 GHz. The sideband separation scheme involves an analog 90 degree hybrid followed by two mixers that provide down conversion of the IF signal to a pair of in phase (I) and quadrature (Q) signals in baseband. The I and Q baseband signals are digitized using 5 Giga sample per second analog to digital converters. A second hybrid is digitally implemented using field programmable gate arrays to produce two sidebands, each with a bandwidth of 1.6 GHz. The 2 x 1.6 GHz band can be tuned to cover any 3.2 GHz window within the aforementioned IF range of the array. Sideband rejection ratios (SRRs) above 20 dB can be obtained across the 3.2 GHz bandwidth by equalizing the power and delay between the I and Q baseband signals. Furthermore, SRRs above 30 dB can be achieved when calibration is applied., 8 pages, 12 figures

When holographic information is transmitted through communication channels, a problem arises associated with the large capacity of holograms. In the patent of the Russian Federation No. 2707582, the possibility of compressing holographic information was shown, similar to the transmission on one sideband known in radio electronics. The experimental transmission of such compressed information over a Wi-Fi wireless communication channel with a frame rate of more than 25 frames per second is shown in this paper. The experiment of transmitting holographic information of 3D images over a wireless Wi-Fi communication channel to simulate 3D video using the FTP protocol was carried out. In accordance with the RF patent No. 2707582, each transmitted frame of a 3D image was the sum of two 2D frames-a texture (2000x2000 pixels) and a mask (1000x1000 pixels). To simulate the transmission of a video sequence, packets of 500 double frames were transmitted simultaneously. The transmission times of these frame packets measured in real time by FileZilla showed that the transmission of full holographic information about a 3D object in real time with a frame rate greater than 25 frames / sec. quite feasible.

Due to its low cost, simple architecture and robustness to fiber dispersion, single sideband (SSB) transmission with direct detection (DD) system is an attractive solution for 80-km inter data center interconnect (DCI). However, it will suffer performance penalty caused by the signal-to-signal beating interference (SSBI). Kramers-Kronig (KK) receiver has been extensively investigated for SSBI elimination by reconstructing the SSB signal. The nonlinear operations in KK algorithm require up-sampling to cope with spectral broadening, which results in high complexity for practical application. Optical signal phase retrieval method based on the minimum phase signal has also been investigated for SSB signal recovery, in which the SSB and DC-Value properties are iteratively imposed on the amplitude signal in frequency domain. In this paper, we propose a low complexity iterative algorithm for minimum phase signal recovery without up-sampling in time domain. Finite impulse response (FIR) filter is applied to iteratively generate the SSB signal and update the phase component. Based on the proposed scheme, the transmission of 30GHz SSB 16-QAM discrete multitone (DMT) signal over 80km single mode fiber (SMF) is successfully demonstrated with the bit error rate (BER) below the hard-decision forward error correction (HD-FEC) threshold of $3.8 × 10^{-3}$. The experimental results show that, the BER performance of KK scheme with up-sampling factor of 2, frequency-domain iteration scheme and our proposed scheme is almost the same. However, compared with the KK scheme, the proposed method can save the numbers of adders and multipliers by the factors of 29 and 7, while the factors are 5.5 and 4 comparing to the frequency-domain iteration scheme.

This paper presents design and characterization of single-chip 110-170 GHz (D-band) direct conversion in-phase/quadrature-phase (I/Q) transmitter and receiver monolithic microwave integrated circuits (MMICs), realized in a 130 nm SiGe BiCMOS process with ft/fmax of 250 GHz/370 GHz. The chipset is suitable for low power wideband communication and can be used in both homodyne and heterodyne architectures. The Transmitter chip consists of a six-stage power amplifier, an I/Q modulator, and a LO multiplier chain. The LO multiplier chain consists of frequency sixtupler followed by a two-stage amplifier. It exhibits a single sideband conversion gain of 23 dB and saturated output power of 0 dBm. The 3 dB RF bandwidth is 31 GHz from 114 to 145 GHz. The receiver includes a low noise amplifier, I/Q demodulator and x6 multiplier chain at the LO port. The receiver provides a conversion gain of 27 dB and has a noise figure of 10 dB. It has 3 dB RF bandwidth of 28 GHz from 112-140 GHz. The transmitter and receiver have dc power consumption of 240 mW and 280 mW, respectively. The chip area of each transmitter and receiver circuit is 1.4 mm x 1.1 mm.

Matching filter (MF)-free digital filter multiplexed (DFM) single sideband (SSB) OFDM intensity modulation and direct detection (IMDD) dual-channel transmissions of 51.25Gbit/s over 25km SSMFs are experimentally demonstrated. It is shown that both transmission system impairments and digital filter characteristic variations can only lead to

Recently, harmonic beamforming in the time-modulated array (TMA) has attracted much attention. In this study, two kinds of beamforming systems of TMA based on the single-sideband time-modulated phased array (STMPA) and enhanced STMPA are presented, and the +1st harmonic beamforming is performed. Based on the basic structure of STMPA and ESTMPA, we transform the design of the I/Q modulator, then the modified STMPA (MSTMPA) and modified ESTMPA (MESTMPA) are presented. The two channels in an I/Q modulator are each connected to an antenna with other structures keep constant. Hence, the number of antennas can be multiplied, and the system complexity can be reduced with an increase in the number of antennas especially for large-scale applications. In addition, the array aperture is enlarged with the same number of I/Q modulators, and the performance of the beam pattern is improved. However, without the single sideband structure, the ( $4k-1\cap 3k)^{\mathrm {st}}$ and ( $8k-1$ )st harmonics in STMPA and ESTMPA cannot be eliminated; therefore, the bandpass filter is used at the output of the system; thus, the +1st harmonic can be extracted. The derivations and analysis are given in detail, and STMPA and ESTMPA compared. Finally, the effectiveness of the proposed systems is verified by simulation results and the +1st harmonic can be formed in desired directions.

In this paper, a bias-free silicon optical single-sideband (OSSB) modulator without 2nd-order sideband is proposed and theoretically investigated. The proposed modulator is based on a dual-drive Mach-Zehnder modulator (DDMZM) and silicon photonics platform. In the proposed structure, a piece of silicon waveguide is used in one of the arms of the unbalanced DDMZM which acts as a bias for the modulator. So, the operating point of the modulator can be tuned by adjusting the optical wavelength. Analytical models for all the components in the structure are derived and closed-form expressions are found for optical transmission, optical spectrum, etc. Modulator nonlinear behavior under small and large signal modulation is discussed. Conditions on the optical wavelength to have an OSSB modulated signal with/without 2nd-order sideband are found. It has also shown that optical carrier-to-sideband ratio (OCSR) can be tuned by adjusting the applied voltage. By proper adjusting the applied voltage, suppressed carrier or equal carrier to the first sideband can be obtained in OSSB modulator without 2nd-order sideband. Analytical results are verified by simulations and previously reported measurement data. The proposed analytical model is a general model that can be used for any nonlinear electro-optic modulators such as phase and absorption modulators.

Filter bank multi-carrier (FBMC) using offset quadrature amplitude modulation (OQAM) has recently attracted increasing interests for the next-generation high-speed optical transmission systems, due to the salient FBMC modulation advantages in terms of high spectrum efficiency by completely removing the cyclic prefix. However, high peak-to-average power ratio (PAPR) still plays a key role of constraining the performance of FBMC systems. In this paper, we investigate a single sideband (SSB) pruned discrete Fourier transform (DFT)-spread FBMC for direct-detection (DD) passive optical network systems (PONs). It is demonstrated that the PAPR of the SSB pruned DFT-spread FBMC signal with the overlapping factor of 1.56 outperforms the conventional FBMC signal and the simple DFT-spread FBMC signal by ~2 dB and 1 dB at the complementary cumulative distribution function (CCDF) of 1 × 10-3, respectively. Finally, by using the pruned DFT-spread FBMC with low PAPR, the aggregate data rate of 50-Gbit/s can be achieved after 50-km single mode fiber (SMF) transmission below the 7% hard decision forward-error correction (HD-FEC) threshold in the DD PONs.

The previously reported hybrid orthogonal frequency division multiplexing-digital filter multiple access (OFDM-DFMA) PONs offer promising solutions for seamlessly converging optical and mobile networks for 5G. However, the hybrid OFDM-DFMA PONs based on intensity-modulation and direct-detection (IMDD) convey double sideband (DSB) signals at different sub-wavelengths, this halves the spectral efficiency and signal transmission capacity. In this article, hybrid single sideband (SSB) OFDM-DFMA PONs are proposed and explored, for the first time, where multiple SSB OFDM channels produced without employing the Hilbert transform operation are multiplexed using orthogonal digital filtering in ONUs, and demultiplexed/demodulated by a single FFT operation in OLT without incorporating matching filters. It is shown that similar to the DSB PON, the proposed SSB PON has excellent robustness against digital filter characteristic variations and channel interferences. More importantly, it decreases peak-to-average power ratios (PAPRs) of digitally-filtered OFDM signals by >2 dB, thus leading to >2 dB reductions in optimum signal clipping ratio and >1 bit reductions in minimum required DAC/ADC resolution bits. For fixed spectral bandwidths, the SSB PON almost doubles the maximum upstream transmission capacity without considerably degrading its differential ONU optical launch power dynamic range compared to the DSB PON. While for fixed upstream signal transmission capacities, compared to the DSB PON, the SSB PON not only halves the overall signal transmission bandwidth, but also leads to >2.5 dB (>1.2 dB) improvements in power budget (differential optical launch power dynamic range for ONUs locating at high frequency regions).

A cooperative design of the advanced time-modulated array (TMA) and the retrodirective (RD) array is introduced to act as a transmitting array for multiuser wireless power transmission (WPT) applications. The conventional rectangular-pulse based TMA is lack of harmonic beamforming flexibility limited by its frequency spectral properties. By preprocessing the rectangular pulses with the sinusoid-based control signal, harmonic beams are independently steerable. The proposed array is enabled with self-phasing capability by taking advantage of the RD technique. Besides, to avoid the unexploited radiation caused by unscannable fundamental beam and specular harmonic beams, the single sideband (SSB) modulator is utilized to enable the transmitting array with high-efficiency beamforming capacity. The numerical results verify that the presented array performs well in various charging scenarios, which brings a highly potential insight for far-field WPT.

For the terahertz harmonic mixer, a design model based on Half-Subdivision and Half-Global Design Method (HS-HGDM) with a single functional unit is proposed. The single functional unit circuit of the mixer, such as LO or IF Low Pass Filter (LPF), is designed by Subdivision Design Method (SDM), and the rest circuits of the mixer are designed by Global Design Method (GDM). The harmonic mixer based on this model is characterized by simple circuit structure, low conversion loss, small circuit size and high stability. In this paper, an improved Compact Suspended Micro-strip Resonators (CSMRs) filter is developed for the IF part of sub-harmonic mixer. The remaining circuits consist of some basic transmission units, such as the High-Z Low-Z impedance Transmission Lines (H-Z L-Z TLs) applied for main circuit, and full/reduced height WR4.3/WR8 applied for providing RF/LO signal. In RF frequency range 200–240 GHz, a Single Sideband (SSB) conversion loss of 7.36±0.76 dB operating at IF frequency 1.8 GHz, and a Double Sideband (DSB) noise temperature below 1034 K with the LO power of 2–5 mW and the LO frequency of 107 GHz were achieved. This broadband sub-harmonic mixer operates at room temperature, which makes it applicable to sub-millimeter wave or terahertz wireless communication systems and imaging inspection systems.

The design of efficient time-modulated arrays (TMAs) for multi-beam steering purposes must be based on both a type of periodical sequences that guarantees an adequate windowing of exploited harmonics, and a feeding network capable of providing low hardware insertion losses. Compliance with these two requirements is not simple and is aggravated by the fact that, as the number of exploited harmonic beams increases, not only drastically decreases the antenna efficiency, but also the beam steering flexibility. In this work, we propose three different single sideband (SSB) feeding networks for multibeam TMAs constructed considering different combinations of single-pole multiple-throw (SPMT) basic modules. The proposed feeding networks simultaneously accomplish excellent levels of modulation efficiency, reasonable hardware insertion losses, and beam scanning flexibility. In addition, a comparison with standard phased arrays in terms of performance, phase sensitivity, complexity, and cost-effectiveness is carried out.

This article presents an enhanced single-sideband time-modulated phased array (ESTMPA) using modulating pulses with stepped waveforms. Based on the in-phase/quadrature (I/Q) complex modulation technique, this phase-only weighting array generates a scanning beam at the 1st sideband. The proposed modulating pulses realized through a reconfigurable power divider in I/Q time modulator can avoid the power loss from the switches during switch-OFF state and eliminate the maximum undesired sideband—the 5th harmonic in STMPA. As a result, it brings a power spectrum with less undesired sidebands, lower sideband level (−16.9 dB), higher harmonic efficiency (94.96%), and wider allowable signal bandwidth (eight times as wide as that of the conventional time modulated array). To experimentally verify the feasibility of the proposed design, a wideband enhanced I/Q time modulator and its corresponding eight-element ESTMPA are designed and manufactured. A detailed study on the effect of the magnitude and phase deviations in the circuit and the transition period of modulating pulse are presented. The measured results of power spectrum and radiation pattern have a good agreement with the simulated ones.

A wideband 220 GHz subharmonic mixer based on monolithic integration technology is proposed in this paper. It features 12 Mm-thick GaAs membrane with anti-parallel Schottky diodes working at THz band monolithically integrated on the membrane. The optimization principles of low-parastics Schottky diodes and the fabrication process of GaAs MMIC membrane diodes are elaborated. To realize optimum performances of the mixer, the dimensions of the integrated diodes and the matching network are optimized with harmonic balance simulation and load-pull techniques. An IF low pass filter with compact microstrip resonance cell (CMRC) configuration and an improved perpendicular coax-to-microstrip connection are used to realize wide IF band. The measured results show that the single sideband (SSB) conversion loss of this mixer is less than 10.5 dB from 185 to 255 GHz with fixed IF of 1 GHz, while the double sideband (DSB) noise temperature is better than 1400 K in this frequency range. Using fixed local oscillator (LO) frequency of 110 GHz, the measured SSB conversion loss is 7.4-10.7 dB within 185-255 GHz, indicating the good performances of the mixer with IF from DC to 35 GHz. The GaAs monolithic integration technology provides an approach for massive manufacturing of identical circuits and the proposed mixer with wideband characteristics will be applied in 220 GHz imaging systems in the near future.

A novel beat interference cancellation receiver (BICR) is proposed to cancel the signal-signal beat interference (SSBI) for polarization division multiplexed (PDM) optical orthogonal frequency division multiplexing (OOFDM) system, where two single sideband (SSB) OOFDM signals are polarization multiplexed along with their offset optical carriers (OCs) located at opposite sides. At receiver, the PDM SSB-OOFDM signal is equally power split into four beams with one or two OCs filtered out, and then fed into two balanced photodiode pairs for recovering the RF-OFDM signals with SSBI cancellation. The PDM SSB-OOFDM system is insensitive to fiber polarization mode dispersion since the proposed BICR is implemented without polarization-sensitive devices. Moreover, the spectral efficiency is greatly improved because of PDM and the small guard band since the SSBIs are eliminated. The proposed BICR scheme is validated with a simulation link of 112 Gbps 16-QAM PDM SSB-OOFDM signals. After 120km SSMF transmission, the EVM keeps below forward error correction limit of 16.3%.

We propose a novel zero guard band (ZGB) multi-twin-SSB bidirectional passive optical network system which combines the multiband carrier-less amplitude phase and twin single sideband (SSB) modulation techniques. The multi-twin-SSB signal is generated at the downlink transmitter side with zero guard band between the left-sideband and right-sideband. A weak local oscillator which is extracted from the uplink optical source aids the downstream signal detection. Kramers-Kronig algorithm is used at both downlink and uplink receiver sides to reconstruct the SSB signal and eliminate the signal-signal beat interference. The downstream and upstream signals are transmitted in a single fiber without any spectral overlap between them and the Rayleigh backscattering noise is removed by the optical band-pass filter. The proposed scheme is extensively investigated and analyzed with four sub-bands using 50 Gbps 16-QAM modulation for each sub-band over a bidirectional 50 km transmission. The results show that, compared with the conventional multi-twin-SSB scheme, the proposed ZGB multi-twin-SSB scheme can improve the spectral efficiency by about 11%. The required optical signal to noise ratio (OSNR) and the required received optical power (ROP) can be reduced by more than 15 dB and 7 dB respectively at the 7% hard decision forward error correction (HD-FEC) threshold (bit error rate of 3.8 × 10-3), respectively. For the uplink transmission, the required ROPs for the inner and outer sub-bands at 7% HD-FEC are about -10 dBm and -11 dBm, respectively. And the signal to noise ratio to the corresponding ROPs for the inner and outer sub-bands are 15.4 dB and 15.3 dB, respectively.

We demonstrate a continuously RF tunable orthogonally polarized optical single sideband (OP-OSSB) generator based on dual cascaded micro-ring resonators. By splitting the input double sideband signal into an orthogonally polarized carrier and lower sideband via TE- and TM-polarized MRRs, an OP-OSSB signal is generated. A large tuning range of the optical carrier to sideband ratio of up to 57.3 dB is achieved by adjusting the polarization angle of the input light. The operation RF frequency of the OP-OSSB generator can be continuously tuned with a 21.4 GHz range via independent thermal control of the two MRRs. Our device represents a competitive approach towards OP-OSSB generation with wideband tunable RF operation, and is promising for photonic RF signal transmission and processing in radar and communication systems.

We present a new electro-optic modulation technique that enables a single laser diode to realize a cold-atom source and a quantum inertial sensor based on matter-wave interferometry. Using carrier-suppressed dual single-sideband modulation, an IQ modulator generates two optical sidebands from separate radio-frequency (rf) signals. These sidebands are controlled independently in frequency, phase, and power using standard rf components. Our laser source exhibits improved rejection of parasitic sidebands compared to those based on phase modulators, which generate large systematic shifts in atom interferometers. We measure the influence of residual laser lines on an atom-interferometric gravimeter and show agreement with a theoretical model. We estimate a reduction of the systematic shift by two orders of magnitude compared to previous architectures, and reach a long-term sensitivity of 15 ng on the gravitational acceleration with an interrogation time of only T = 20 ms. Finally, we characterize the performance of our integrated laser system, and show that it is suitable for mobile sensing applications including gravity surveys and inertial navigation., Comment: 14 pages, 11 figures

With the rapid development of wireless systems, the demand for frequency resources has been increasing in recent years. Therefore, it is necessary to consider the high-quality communication method that efficiently utilizes finite frequency resources. In this paper, Single Sideband 16 Pulse Amplitude Modulation (SSB 16PAM) scheme for the uplink communication is proposed. It transmits data in only Lower Sideband (LSB) without extra Hilbert components. Under Additive White Gaussian Noise (AWGN) channel environment, Bit Error Rate (BER) performance of the proposed scheme is superior by 3 dB in terms of Carrier-to-Noise Ratio (CNR) to 256 Quadrature Amplitude Modulation (256QAM) scheme with the same frequency efficiency and the same Peak-to-Average Power Ratio (PAPR). Our proposed scheme employs the original frequency domain filter on the transmitter side to form an ideal spectrum. The configuration of its process is almost similar to Single Carrier-Frequency Division Multiple Access (SC-FDMA), moreover, half of the input data on the frequency domain is removed. The proposed frequency domain filter produces the SSBmodulated spectrum with a roll-off rate of zero without degrading the BER performance.

We propose and experimentally demonstrate a multi-frequency optoelectronic oscillator (OEO) based on phase-modulation to intensity-modulation (PM-IM) conversion. A microwave photonic filter (MPF) incorporating an optical fiber Bragg grating Fabry-Perot (FBG-FP) filter and an electrical yttrium iron garnet (YIG) filter in two branches are used to select the oscillation modes of the OEO. By adjusting the wavelength of laser source or the central frequency of YIG filter, two frequencies can be tuned independently within a wide range. The single sideband (SSB) phase noises of the generated frequencies are measured experimentally. Moreover, the OEO shows potential ability to achieve more frequencies oscillation by multiplexing more optical and electrical filters.

A 30 MHz–3.6 GHz wideband frequency synthesizer with a self-biased oscillator and quadrature-input quadrature-output (QIQO) dividers for software-defined radio applications is presented in this brief. The self-biased oscillator employs a novel cross-coupled negative-Gm pair that performs an equivalent linearized negative resistance, mitigating the noise folding process. The QIQO dividers are utilized to divide the quadrature signals and incorporate with a quadrature single sideband mixer for post synthesizing. The synthesizer is implemented in TSMC 180-nm RF CMOS process and provides a phase noise performance of −125.4 dBc/Hz and −122.9 dBc/Hz at 1 MHz offset under 1.8- and 2.7-GHz carriers, respectively. The maximum power consumption is 135 mW and the die size, including pads and I/O is 2.9 mm $^{{2}}$ .

The high optical bandwidth requirement in the mobile fronthaul link of the next generation cloud radio access network represents one of the major design constraints. In this study, a digital fronthaul link based on digital radio over fibre system that integrates the duobinary coding scheme with the optical single sideband (OSSB) transmission is proposed. This system reduces the spectral occupancy of the transmitted signals as well as the chromatic dispersion effects induced by fibre in both the electrical and optical domains. The OSSB signal is created by driving two cascaded optical modulators with a combination of a baseband digital signal and the Hilbert transform of that signal. The transmission performance of a digitised 16-quadrature amplitude modulation 16-QAM radio frequency signal with a bit rate of 1.25 Gb/s over a standard single mode fibre is investigated. The results show that the fronthaul transmission length can be extended by 75 and 16.6% relative to the case of transmitting the digitised signal using double sideband and single sideband (SSB) transmission formats, respectively. The power budget is improved by 10 dB compared to the SSB case with respect to the measured optical signal-to-noise ratio at 70 km fibre distance, while maintaining the EVM below the standardised values of the 3GPP.

A scalable four-channel multiple-input multiple-output (MIMO) radar that features a modular system architecture and a novel frequency-division multiplexing approach is presented in this article. It includes a single 30-GHz voltage-controlled oscillator (VCO) for the local oscillator signal generation, four cascaded 120-GHz transceivers with a frequency quadrupler, and on-board differential series-fed patch antennas. The utilized uniform antenna configuration results in 16 virtual array elements and enables an angular resolution of 6.2°. The vector modulators in the transmit (TX) paths allow the application of complex bit streams of second-order delta–sigma modulators easily generated on a field-programmable gate array (FPGA) to implement single-sideband (SSB) modulation on the TX signals resulting in orthogonal waveforms for the MIMO operation. Only one phase-locked loop and no digital-to-analog converter is required. The waveform diversity also allows the simultaneous transmission of the TX signals to reduce the measurement time. The application of the SSB modulation on the frequency-modulated continuous-wave MIMO radar requires only half of the intermediate frequency bandwidth compared with the double-sideband modulation. The issue of the phase and amplitude mismatches at the virtual array elements due to the scalable radar architecture is addressed and a calibration solution is introduced in this article. Radar measurements using different numbers of virtual array elements were compared and the digital-beamforming method was applied to the results to create 2-D images.

Wireless brain–computer interfaces (BCIs) are highly energy constrained because of the need to minimize battery size and weight, as well as the need to minimize the thermal dissipation into the living tissue. We demonstrate an ultralow-power Bluetooth Low Energy (BLE) v5.0 compatible backscatter communication uplink for the NeuroDisc BCI. This backscatter approach is compatible with completely unmodified BLE devices such as PCs, smartphones, and tablets and has an energy consumption of under 200 pJ/bit, over $50\times $ less than commercially available BLE transmitters. This article is the first to present an analysis and demonstration of single sideband (SSB) BLE backscatter, which increases the available channel power by +3 dB while suppressing out-of-channel emissions. An analytic model of SSB backscatter communication is provided, along with simulations showing how nonidealities in the achieved backscatter constellation impact opposite-sideband suppression. The experimental measurements of in-channel gain and opposite-sideband suppression are provided. Additional experiments demonstrate a range of 6 m using a +20-dBm external carrier source and an unmodified Nordic Semiconductor nRF51DK BLE adapter, while uplinking prerecorded neural data sampled at 500 Hz.

A full-duplex radio-over-fibre (RoF) system based on an integrated silicon ring modulator is proposed and demonstrated. For the downstream link, a coherent dual-wavelength laser source is coupled to a silicon ring modulator in the central office (CO). Since only one of the optical carriers in the dual-wavelength laser source is aligned to the resonance of the ring modulator, a single sideband (SSB) modulated optical downstream signal is obtained, which is able to combat the power fading introduced by the fibre dispersion. Besides, for the upstream link, the unmodulated optical carrier in the SSB-modulated optical downstream signal is reused by using an optical filter in the remote radio head. After being modulated by the upstream data, the optical upstream signal is transmitted back to the CO. A proof-of-concept experiment is carried out. Error vector magnitudes of 21-GHz downstream and 10-GHz upstream signals are measured, which confirms that the proposed architecture is a promising low-cost solution for future high-speed wireless communication systems.

A novel push-pull modulator based scheme to generate W-band millimeter-wave (mm-wave) vector signal was proposed and experimentally demonstrated. Related to an I/Q modulator, push-pull modulator has the advantages of simple architecture, small insertion loss and low cost. Through combining one 40 GHz upper sideband (USB) using a quadrature-phase-shift-keying (QPSK) modulation with a −40 GHz unmodulated lower sideband (LSB), a QPSK modulated 4 G-Baud 80 GHz single sideband vector mm-wave signal was successfully generated.

In this paper, a novel scheme to generate multichannel single sideband (SSB) optical signals enabled by one single I/Q modulator based on digital signal processing (DSP) is proposed, which is more flexibility and stability for the future 5G broadband access network instead of complex multiple lasers construction. Four sub-channels carrying different vector quadrature amplitude modulated (QAM) data are modulated to the upper sideband (USB) by I/Q modulation, while the vector unmodulated RF signal is located at the lower sideband (SSB) of the suppressed center carrier. They are used to generate four different mm-wave carriers after heterodyne beating. Due to the imbalance effect of I and Q components from the I/Q modulator, we also optimize the frequency of USB and LSB to reduce the crosstalk between the USB and LSB signal. The experimental results indicate that four-channel QPSK (2 × 2 × 4 = 16 Gbit/s) and 16-QAM (2 × 4 × 4 = 32 Gbit/s) signals with 5 GHz channel spacing at Q-band can be transmitted over 80 km single-mode-fiber 28 and 0.5 m wireless link without dispersion compensation.

For their capability of electronic dispersion compensation, transmission systems based on direct detection of single-sideband (SSB) signals are attractive candidates as energy-efficient and cost-effective alternative solutions to intradyne digital coherent systems for interdata center and metro applications. The Kramers–Kronig (KK) receiver scheme has been shown to provide superior performance compared to other schemes in signal-to-signal beat interference (SSBI) cancelation in these direct-detection systems. In this paper, we propose a low-complexity and cost-effective scheme of generating an optical superchannel comprising multiple SSB channels, based on a single quantum-dot mode-locked laser source. The proposed system does not require additional photonic or RF components at the transmitter to generate the required SSB signal with a continuous wave (CW) carrier. It also preserves the full digital-to-analog converters’ bit resolution for data modulation, in contrast to other methods based on digital generation of the CW component. Simulations of system performance with KK receiver, based on measured laser output field, show that the proposed system can achieve bit-error ratio below the hard-decision forward error correction threshold for 16-QAM Nyquist SSB signals after transmission through three amplified spans of single-mode fiber in a 240-km link. Using 8 KK channels at 23 GBaud each, the proposed scheme will be able to achieve a transmission rate of 736 Gb/s with noncoded spectral efficiency of 2.45 b/s/Hz. The impacts of carrier-to-signal power ratio, per channel launch power into the fiber, and component frequency drifting on transmission system performance are also discussed.

This paper presents a 10.56-GHz transceiver with ultracompact transformer-based transmit/receive (T/R) switching via matching network reuse. The reused transformer can operate as T/R switch and impedance matching networks for a power amplifier (PA) and a low-noise amplifier (LNA) simultaneously. The T/R switch, PA, and LNA are fully codesigned, and the interstage matching networks of the PA and LNA are comatched with the T/R switch to improve the performance of the front end (FE). A three-coil transformer is introduced in the PA to improve the linearity and bandwidth of the FE in the transmit (TX) mode. A mode selection unit (MSU) is also utilized in LNA to improve the TX/RX isolation and the linearity of the FE in the TX mode. Utilizing the fully codesign technique in the FE, the bandwidth of the FE is extended to over 4.2 GHz in both the TX and RX modes. A novel “gm-cell-based” broadband programmable gain amplifier (PGA) and a third-order transconductance-capacitor (gm-c) low-pass filter (LPF) are used in analog baseband to provide over 24-dB gain and 1.8-GHz bandwidth adjustment range with ultralow dc power consumption. To prove the concept, the new architecture is implemented in 28-nm CMOS technology. Measurement results prove that the insertion loss of the proposed T/R switch introduced in both the TX and RX modes is ~0.5 dB, and benefiting from this, the RX obtained a 4.2-dB noise figure, and TX obtained 9.9- and 14.1-dBm OP1dB and Psat. The measured single sideband bandwidth of the transceiver is wider than 2.1 GHz in both the TX and RX modes.

A chirp-rate-tunable microwave photonic pulse compression system for multi-octave linearly chirped microwave waveform (LCMW) is proposed in this paper. The key components are a dual-parallel Mach-Zehnder modulator (DPMZM) and a dispersive loop (DL) structure based on a linear chirped fiber Bragg grating. By controlling the output of the DL to change the accumulated group velocity dispersion, the chirp rate of the system can be tuned. By adjusting the wavelength of the optical carrier to select the single sideband modulated optical signal (positive or negative sideband), the chirp direction (down or up chirped) can also be tuned. The performance of the multi-octave LCMW pulse compression can be improved by eliminating the second-order harmonic distortion through configuring the bias voltages of the DPMZM. Detailed theoretical analysis is conducted. A verification simulation demonstrates the pulse compression of the multi-octave LCMWs with the chirp rates of 23.877, 11.939, 3.979, and -3.979 GHz/ns. In the proof-of-concept experiment, the matched chirp rates 23.229, 12.051, -22.568, and -11.355 GHz/ns are obtained. The multi-octave LCMW pulse compressions with the compression ratios of 14.3, 29.3, 15.0, and 28.6 are verified. The simulation and experiment results are in good agreement with the theoretical analysis.

We experimentally demonstrate the generation of a single-sideband orthogonal frequency division multiplexed (OFDM) signal using an on-chip silicon photonics microring-based IQ modulator. Over 18-dB sideband suppression ratio is achieved for the wideband OFDM: 15.7-GHz data band and 2.7-GHz guard band. The 31.4-Gb/s signal was transmitted over 20 km of standard single-mode fiber with a bit error rate below the forward error correction threshold. While single-sideband continuous-wave signals have been produced with such hardware, this is the first demonstration of stable data transmission on the single sideband carrier.

Radio-over-fiber (ROF)-based mobile fronthaul network supporting the baseband unit and simple remote radio head is a promising network architecture for future wireless networks. In this paper, we propose and demonstrate a silicon photonics (SiPh)-based remote radio frontend (RRF) for the mm-wave ROF systems. The proposed SiPh-based RRF consisted of an integrated Mach-Zehnder modulator and a micro-ring modulator, producing a single-sideband 40 GHz millimeter-wave orthogonal-frequency-division-multiplexing ROF signal, which is robust against fiber chromatic dispersion in the mobile fronthaul transmission. The RRF is fabricated using SiPh platform and could be potentially low cost. High split-ratios can be potentially achieved. Data rate of 7.813 Gbit/s per wavelength channel is achieved in the experiment. Numerical analysis is also performed; there are good matches of the simulation and experimental results.

A photonics-assisted super-octave microwave phase shifter is proposed. The super-octave frequency range is achieved by eliminating the second-order distortions (SDs) with the techniques of polarization interleaving and second-order optical sidebands (2-OSBs) phase processing. Polarization interleaving is based on a polarization-multiplexing dual-drive Mach-Zehnder modulator (PM-DMZM) and single sideband with carrier (SSB+C) modulation. 2-OSBs phase processing is implemented by introducing opposite phase shifts to the ±2-OSBs in a Fourier-domain optical processor (FD-OP). The proposed phase shifter is experimentally verified by proof-of-concept experiments. Experimental results show that flat phase shifts cover a full 360° range with less than 3-dB power variation over 11.5-25 GHz. Besides, excellent long-term stability is presented with a maximum phase/power fluctuation of only 1.49°/0.57 dB. Compared with the conventional FD-OP-based photonic microwave phase shifter, the proposed one improves the second-order spurious free dynamic range (SFDR2) by 13.57 dB.

A new microwave photonic frequency up converter is presented. It is capable to generate an up converted upper or lower sideband RF signal with the other sideband and the LO being suppressed. Compared to the reported photonics-based single sideband (SSB) frequency up converters, the proposed structure is simple and does not require high-frequency electrical components. The upper or lower sideband can be selected by controlling a modulator bias voltage. The new photonics-based SSB mixer is experimentally verified. Around 30 dB suppression in the undesired frequency components adjacent to the up converted RF signal is demonstrated for different input LO and IF signal frequencies when the SSB mixer is operated in either upper or lower sideband mode.

Recently, high-speed optical transmission using single-side-band (SSB) modulation with Kramers-Kronig (KK) scheme has gained great attention due to its high spectral efficiency (SE) and capability of electronic chromatic dispersion compensation (CDC), which can be widely employed in optical metro networks as a promising transmission scheme. To our knowledge, the carrier-signal power ratio (CSPR) is the key parameter to SSB-based systems and the optimum CSPRs can vary distinctly in different SSB modulation schemes. In this paper, the SSB-based KK systems with four kinds of SSB signal generation schemes are investigated, i.e. optical carrier-assisted SSB (OCA-SSB), virtual carrier-assisted SSB (VCA-SSB), SSB subcarrier modulation (SSB SCM) with IQ modulator (IQM) and with dual-drive Mach-Zehnder modulator (DDMZM) respectively. Here, the detailed theoretical derivations of these modulation processing are given and the theoretical relationship between device parameters and the CSPR has been further studied for the different SSB schemes. In order to verify those theoretical analyses, a 224-Gb/s direct detection (DD) transmission with SSB 16-ary quadrature amplitude modulation (16-QAM) signal has been demonstrated based on four SSB generation methods. The results show that theoretical derivations are closely consist with numerical analysis, such as $V_{bias}$ in the scheme of SSB SCM with IQM and optical modulation index (OMI) in SSB SCM with DDMZM. Therefore, our research can provide a theoretical guidance of appropriate device parameter configuration so as to achieve the optimum performance for SSB systems.

The use of single sideband (SSB) signals and envelope detection is a promising approach to enable the use of economic free-running lasers in photonic THz communications. To combat the signal–signal beat interference associated with envelope detection, broad guard bands (GBs) may be used given the large unregulated spectrum available at THz frequencies (100 GHz–10 THz). In this scenario, the conventional way of generating SSB signals through a digital SSB filter (here referred to as the CSSB scheme) would require quite high analog digital-to-analog converter (DAC) bandwidths (BW). Digital virtual SSB (DVSSB) and analog virtual SSB (AVSSB) have been proposed in direct-detection optical systems for relaxing the DAC BW requirements. In this paper, we compare the three techniques through simulations and implement them, for the first time, in a THz-over-fiber system operating at 250 GHz. For the transmission experiments, we employ 5 GBd 16-quadrature amplitude modulation signals with three different GBs (5.5, 4.75, and 3.5 GHz). The simulations show that the best performance is obtained with the AVSSB technique, while the worst is obtained with the DVSSB scheme, where the quality of the generated sideband degrades with carrier-to-sideband power ratio. In the experimental transmissions, where receiver noise was the main source of noise, similar behavior was found between the three techniques. At the 3.5 GHz GB, however, the DVSSB exhibited a penalty of 1 dB with respect to the other two. This is likely to be due to nonlinear distortions caused by the increase in the virtual tone power.

Optoelectronic devices which play important roles in high-speed optical fiber networks can offer effective measurement methods for optoelectronic devices including optical modulators and photodetectors. Precise optical signal modulation is required for measurement applications. This paper focuses on high-speed and precise optical modulation devices and their application to device measurement. Optical modulators using electro-optic effect offers precise control of lightwaves for wideband signals. As examples, this paper describes frequency response measurement of photodetectors using high-precision amplitude modulation and wavelength domain measurement of optical filters using fast optical frequency sweep. Precise and high-speed modulation can be achieved by active trimming which compensates device structure imbalance due to fabrication error, where preciseness can be described by on-off extinction ratio. A Mach-Zehnder modulator with sub Mach-Zehnder interferometors can offer high extinction-ratio optical intensity modulation, which can be used for precise optoelectronic frequency response measurement. Precise modulation would be also useful for multi-level modulation schemes. To investigate impact of finite extinction ratio on optical modulation, duobinary modulation with small signal operation was demonstrated. For optical frequency domain analysis, single sideband modulation, which shifts optical frequency, can be used for generation of stimulus signals. Rapid measurement of optical filters was performed by using an optical sweeper consisting of an integrated Mach-Zehnder modulator for optical frequency control and an arbitrary waveform generator for generation of a source frequency chirp signal.

We report narrowband orthogonally polarized optical RF single sideband generators as well as dual-channel RF equalization, both based on high-Q integrated ring resonators. The devices operate in the optical telecommunications C-band and enable RF operation over a range of either fixed or thermally tunable frequencies. They operate via TE/TM mode birefringence in the resonator. We achieve a very large dynamic tuning range of over 55 dB for both the optical carrier-to-sideband ratio and the dual-channel RF equalization for both the fixed and tunable devices.

This study revokes the performance of continuous phase modulation (CPM) able to generate a single-sideband (SSB) spectrum directly. This signal is analyzed in terms of modulation indices, pulse lengths, and pulse widths, all of which affect error probability, bandwidth, SSB property, and receiver complexity. The error probability performance is based on an approximation of the minimum Euclidean distance. A numerical power spectral density calculation for this particular SSB modulation in terms of modulation index is presented. Reasonable tradeoffs in designing modulation schemes have been proposed using multi-objective optimization to ensure sizable improvements in bit error rate (BER), spectral efficiencies, and complexity without losing the property of being a SSB signal. Performance comparisons are made with known CPM schemes, e.g., Gaussian Minimum Shift Keying (GMSK) and Raised Cosine based CPM (RC), We added a new optimization method to take into consideration the complexity. - We added a new comparison between new SSB-FSK schemes and the CPM modulations (RC, GMSK). - We presented a new SSB-FSK scheme with some good synchronization advantages. - We fixed some typo mistakes. - We updated the overall quality of the paper

We report the current progress in the development of a compact, deployable cold-atom interferometry sensor platform towards atomic sensors for position, navigation, and time (PNT) applications. A simplified atomic sensor head with diffractive optics, an alignment-free optical package, and photonic-integrated-circuit (PIC) compatible laser architecture [1] are essential for its compactness and deployability. This cold-atom sensor platform can be generally applied to gravimeters, accelerometers, gyroscopes, and clocks, and the sensor platform includes significant engineering efforts in the development of grating-mirror magneto-optical traps (G-MOTs), custom titanium vacuum package with passive pumping, and silicon photonics multi-channel on-chip single sideband modulators.