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A simple and flexible photonics-assisted approach based on an integrated polarization-division multiplexing Mach–Zehnder modulator (PDM-MZM) and a balanced photodetector (BPD) to generating microwave waveform is proposed. The sub-MZMs of PDM-MZM are biased at peak and null points. Square and trapezoid waveforms are generated by controlling the PC and driven sinusoidal signal power. Triangle and sawtooth waveforms are also obtained with the help of a 90° microwave phase shifter (MPS). The proposed approach features simple structure, flexible frequency tunability, and easy implementation. Moreover, the problem of high root-mean-square error (RMSE) of square waveform is solved by this approach for the first time. An experiment is conducted to verify the approach. Different waveforms with the repetition rates of 3 and 5 GHz are generated. The RMSE of square waveform is reduced from 0.3328 to 0.2048 which is the lowest RMSE to the best of our knowledge.

In this letter, a simple and spectral-efficient self-homodyne-detected microwave photonic link is proposed and experimentally demonstrated. At the transmitter, a phase-modulated optical signal and an intensity-modulated optical local oscillator signal are polarization-multiplexed and delivered in a single fiber over long distance. At the receiver, the two signals are coherently detected by a self-homodyne interferometer and then demodulated through simple digital signal processing. The proposed scheme is experimentally validated by 25-km fiber transmission of the 50-Msymbol/s 16-QAM microwave vector signals at 2 and 2.5 GHz. The transmission performance compared with the conventional homodyne detection scheme in terms of error vector magnitude and bit error rate is evaluated. The proposed scheme can be a potential solution to wireless access networks for both high spectral efficiency and low-cost implementation.

We propose a photonic pre-distortion technique to perform self-interference cancellation for radio-frequency signals. The intensity-modulation direct-detection system is modified by adding a Mach-Zehnder modulator and an optical delay line. With a prior knowledge of the interferer, the optical carrier is pre-distorted before modulated by the received corrupted signal. The delay and amplitude adjustments in our system are optically implemented. Experimental results show that the system achieves 32.6 dB of cancellation across 100-MHz bandwidth and 57 dB of cancellation for 10-KHz narrowband interference.

A novel approach to generate phase-coded microwave signals using a dual-polarization quadrature phase shift-keying (DP-QPSK) modulator is proposed and experimentally demonstrated. The key component of the proposed scheme is a DP-QPSK modulator, in which, the upper dual parallel Mach-Zehnder modulator (DP-MZM) modulated by a coding signal is properly biased to implement equivalent phase modulation, while the lower DP-MZM modulated by an RF signal functions as an optical wavelength shifter. A phase-coded microwave signal is generated by beating the phase-modulated optical carrier and the wavelength-shifted optical sideband at a photodetector. The proposed approach has a compact structure and great reconfigurability. By applying different coding signals, binary or quaternary phase-coded signals can be generated. A proof-of-concept experiment is carried out. The generation of binary and quaternary phase-coded signals with a microwave carrier frequency at 8 and 13 GHz is demonstrated.

We propose a simple microwave frequency measurement approach utilizing a phase modulator. After properly adjusting the polarization controllers in the proposed system, two dispersion-induced power penalty functions with different variation trends are obtained. A distinct relationship between the power ratio and the microwave frequency can be constructed by comparing the two power penalty functions. Thus, the microwave frequency can be determined by the power ratio value. Since only a bias drift free phase modulator and a single laser source are needed, the measurement system is significantly simplified. In the experiment, a frequency measurement over the range of 1.6–24.6 GHz with measurement errors within ±0.3 GHz is achieved.

The synchronization properties and the sensitivity of generalized lag synchronization (GLS) in all-optical star network with mutually coupled semiconductor laser in the presence of heterogeneous delays are investigated numerically. The hub node and the side nodes are optically coupled with asymmetrical injection strength. The dependence of GLS on the effects of lasers’ pump current, injection strength, asymmetrical injection factor, and frequency detuning distribution is examined. It is found that, except for the injection strength and frequency detuning, the pump current of hub laser and the asymmetrical injection factor are also key factors that determine the quality of GLS in star network with heterogeneous delays. Extremely asymmetrical injection as well as large pump current of hub laser is suggested to obtain high-quality GLS in wide parameter regions. Such GLS can also be obtained in a large-scale laser network with heterogeneous coupling delays, and is hardly affected by the time delay distribution, which opens possibilities for multi-user chaotic communication and synchronization-based secure key distribution network among the side nodes.

A photonic microwave signal generation scheme with frequency octupling is proposed and experimentally demonstrated using a dual-polarization quadrature phase shift keying modulator. By properly setting the phase difference between the two drive signals, the working points of the modulator, and the polarization state of the light wave after the modulator, an optical signal with only ±4th order sidebands is generated. A pure 24-GHz microwave signal with low-phase noise is experimentally obtained using a 3-GHz local oscillator signal. The proposed photonic frequency octupling system also exhibits good frequency tunability as no electrical or optical filter is used.

A simple and low cost analog photonic link with the compensation of dispersion-induced power fading is proposed and demonstrated using a dual-electrode Mach–Zehnder modulator. In the proposed link, the modulator is single-electrode driven to realize a novel double-sideband (DSB) modulation. By adjusting the dc bias of the modulator, the frequency response of a dispersive link can be controlled to compensate the power fading at any working frequency. Experimental results show that the power fading in a conventional DSB modulated link after fiber transmission over 25 and 50 km can be both successfully compensated in the proposed link, and the spurious-free dynamic range at 12 GHz of a link with 25 km of single-mode fiber is improved by 11.6 dB.

A novel scheme to optically generate a microwave signal with frequency sextupling is proposed. The proposed scheme is based on cascading an intensity modulator (IM) and a dual-parallel Mach-Zehnder modulator (DPMZM), without any optical or electrical filter. The low frequency local oscillator signal is divided into two paths, with one path driving the IM at the minimum transmission point and the other path driving the upper arm of the DPMZM. By controlling the three dc biases of the DPMZM, the third-order sidebands are generated, with other sidebands well suppressed. A 20-dB electrical spurious suppression ratio is demonstrated in the experiment. The phase noise measurements show that the phase noise performance of the generated microwave signal is not deteriorated by the optical system. The proposed scheme has no strict requirements for the modulation indexes and the generated signal exhibits advantages of high frequency tunability and purity.

A novel photonic approach to generating a precisely π phase-shifted binary phase-coded microwave waveform with ultra-wide frequency tunable range is proposed and experimentally demonstrated. In the proposed system, a polarization modulator (PolM) functions in conjunction with a polarization controller (PC) and an optical polarizer (Pol) as an equivalent Mach-Zehnder modulator (MZM) with the bias point switchable by applying a binary-coding signal to the PolM. To generate a phase-coded microwave signal at a specific microwave frequency, the binary-coding signal is combined with a microwave signal at that frequency and applied to the PolM. By switching between the two quadrature transmission points or the maximum and the minimum transmission points, a phase-coded microwave waveform at the fundamental or doubled frequency is generated. The proposed technique is experimentally evaluated. A phase-coded microwave waveform at the fundamental and doubled frequency is generated. The tunability of the approach is also experimentally demonstrated.