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This paper studies the phenomenon of light-excited entanglement between nucleon spins, which is realized by using a transient light beam to excite the spin of electrons to produce entanglement between the two nucleon spins. This standard three-body interaction system is composed of an intermedium equivalent to a spin-1 quasiparticle and two spin-1/2 nucleons. We describe the entire system, its corresponding effective Hamiltonian, and the eigenvalues and eigenstates. The Hamiltonian is analyzed under the symmetric assumption, which can significantly simplify the effective Hamiltonian and make obtaining the corresponding dynamic characteristics easier. In the calculation process, degenerate perturbation theory calculates the eigenequation, whose degeneracy is not eliminated to a first approximation. We calculate the eigenequation to the second order to obtain an accurate zero-order wave function.

An all-optical radio-over-fiber (RoF) link with double spectral-efficient transmission and compensation of chromatic dispersion-induced power fading is proposed and experimentally demonstrated. At the central office, a commercial dual-polarization quadrature phase-shift keying modulator is utilized to produce a polarization-multiplexed signal composed of two modulated microwave vector signals and an unmodulated optical carrier. At the remote node, by adjusting the polarization controller to introduce a proper phase shift to the unmodulated optical carrier, the two vector signals can be demodulated respectively and dispersion-induced power fading can be compensated simultaneously. The link performance is evaluated by error vector magnitude and bit error rate.

In this paper, a novel spectral-efficient coherent radio-over-fiber (RoF) link with linear digital phase demodulation is proposed and experimentally demonstrated. At the transmitter, to make an efficient use of the optical power and spectra, an intensity-modulated optical signal serving as the optical reference signal and a phase-modulated optical signal are polarization-multiplexed on a single optical carrier. At the receiver, the two optical signals are coherently detected with an optical local oscillator (OLO) and demodulated free of laser phase fluctuation through digital signal processing. Owing to simple and linear digital phase demodulation, an RF input signal is linearly demodulated from the optical phase without approximations and preconditions, which preserves the linearity of the phase-modulated RoF optical link from the transmitter end to the receiver end. The proposed scheme is experimentally verified by 25-km single-mode-fiber (SMF) transmission of two 16-QAM microwave vector signals at 2 GHz and 2.4 GHz, both with a symbol rate of 50 Msymbol/s. The transmission performance in term of error vector magnitude (EVM) is evaluated. Additionally, 25-km SMF transmission of the phase-modulated input signal with a spurious-free dynamic range (SFDR) of 112.8 dB·Hz2/3 is obtained.

A novel photonic scheme of binary modulated microwave signals generation based on a dual-polarization quadrature phase-shift keying (DP-QPSK) modulator is proposed and experimentally demonstrated. The scheme is highly reconfigurable, amplitude keying signal (ASK), phase-shift keying signal (PSK) or frequency-shift keying (FSK) signal can be generated by appropriately setting the amplitude of the binary coding signal. The coding signal and local oscillator (LO) signals are independent with each other, binary modulated microwave signals can be generated with arbitrary coding rate and carrier frequency. The frequency deviation of the FSK signal can also be adjusted flexibly. No filter is used in the scheme and the tuning range is large. A proof-of-concept experiment is carried out to verify the feasibility of the proposed system. A 1-Gbps 8-GHz microwave ASK signal, a 0.5-Gbps 6-GHz microwave PSK signal, and a 0.5-Gbps 8/12-GHz microwave FSK signal are g[enerated in the experiment.

In order to reduce resource consumption and improve transmission efficiency, in this paper, using single-particle states, a multiparty quantum privacy comparison size relationship (QPCSR) protocol is proposed. Without leaking the compared private message, the blinded secret integer is encoded into the relative phase of single-particle by performing unitary operation. After each of the transformed quantum states has been measured, respectively, the comparison result of n participants' secret integers is obtained. Security analysis shows that this protocol not only resists outside attack and participant attack, but also resists the semi-honest third-party (TP) attack. Compared with the other similar quantum privacy comparison equal relationship (QPCER) protocols, the proposed protocol has better flexibility and universality; compared with the other similar QPCSR protocols, it has lower resource consumption and higher communication efficiency.

Photonic spiking neural networks (SNN) have the advantages of high power efficiency, high bandwidth and low delay, but limitations are encountered in large-scale integration. The silicon photonics platform is a promising candidate for realizing large-scale photonic SNN because it is compatible with the current mature CMOS platforms. Here, we present an architecture of photonic SNN which consists of photonic neuron, photonic spike timing dependent plasticity (STDP) and weight configuration that are all based on silicon micro-ring resonators (MRRs), via taking advantage of the nonlinear effects in silicon. The photonic spiking neuron based on the add-drop MRR is proposed, and a system-level computational model of all-MRR-based photonic SNN is presented. The proposed architecture could exploit the properties of small area, high integration and flexible structure of MRR, but also faces challenges caused by the high sensitivity of MRR. The spike sequence learning problem is addressed based on the proposed all-MRR-based photonic SNN architecture via adopting supervised training algorithms. We show the importance of algorithms when hardware devices are limited.

Abstract The spike encoding properties of two polarization-resolved modes in vertical-cavity surface-emitting laser with an embedded saturable absorber (VCSEL-SA) are investigated numerically, based on the spin-flip model combined with the Yamada model. The results show that the external input optical pulse (EIOP) can be encoded into spikes in X-polarization (XP) mode, Y-polarization (YP) mode, or both XP and YP modes. Furthermore, the numerical bifurcation diagrams show that a lower (higher) strength of EIOP is beneficial for generating tonic (phasic) spikes; a small amplitude anisotropy contributes to wide (narrow) tonic spiking range in XP (YP) mode; a large current leads to low thresholds of EIOP strength for both XP and YP modes. However, the spike encoding properties are hardly affected by the phase anisotropy. The encoding rate is shown to be improved by increasing EIOP strength. Moreover, dual-channel polarization-multiplexed spike encoding can also be achieved in a single VCSEL-SA. To the best of our knowledge, such single channel polarization-resolved and dual-channel polarization-multiplexed spike encoding schemes have not yet been reported. Hence, this work is valuable for ultrafast photonic neuromorphic systems and brain-inspired information processing.

A microwave photonic system that can realize frequency up- and down-conversion, multichannel phase shift, high conversion gain, and elimination of dispersion-induced power fading is proposed and experimentally demonstrated. The scheme is based on an integrated dual-polarization quadrature phase shift keying modulator that contains two dual parallel Mach-Zehnder modulators (X-DPMZM and Y-DPMZM). The X-DPMZM implements dual side band carrier suppression (DSB-CS) modulation of radio frequency signal, and the Y-DPMZM implements frequency shift of an optical carrier. They are combined in orthogonal polarizations to implement frequency up- and down-conversion. The polarization multiplexed signal will go through polarization controllers and polarizers to implement multichannel phase shift. In the experiment, the phase shift can be tuned independently over 360° in each channel. By suppressing the optical carrier, the conversion gain and LO isolation are improved by 20.5 dB and 51.26 dB, respectively, compared with conventional dual side band modulation scheme. In addition, the proposed scheme can achieve a spurious-free dynamic range (SFDR) of 103.6 dB·Hz2/3.

A wideband microwave Doppler frequency shift (DFS) measurement approach based on a single dual-parallel Mach-Zehnder modulator (DPMZM) is proposed and experimentally demonstrated. The light wave is modulated by the transmitted and echo signals in the DPMZM to generate carrier suppressed double sidebands signals. Based on the phase difference and powers of the upper bands and lower bands of the modulated signal, the DFS value, as well as the sign, can be measured. An experiment is carried out. The DFS from -100 to +100 kHz at the carrier frequencies of 10, 20, 30, and 39 GHz is accurately measured with errors of less than 5 × 10-6 Hz.

Optical carrier to sideband ratio (CSR) optimization and balanced detection are two effective techniques to improve the performance of an analogy photonic link (APL). Here, we proposed an APL where tunable optical CSR and balanced detection can both be implemented. A single integrated polarization division multiplexing Mach-Zehnder modulator (PDM-MZM) is used to generate a polarization multiplexed signal containing an optical carrier and two radio frequency modulated sidebands, and the optical CSR can be tuned from -15 to 15 dB by simply adjusting the direct current bias of the modulator. By optimizing the optical CSR in the proposed link, the link gain and noise figure (NF) are improved by 12 and 6.8 dB compared with conventional quadrature biased link. In addition, after balanced detection in the proposed link, the link gain, NF, third-order spurious free dynamic range (SFDR), and especially the second-order SFDR are further improved.

We propose and experimentally demonstrate a photonic approach to estimate the angle-of-arrival (AOA) of broadband microwave signals. Using an integrated polarization-division multiplexing Mach–Zehnder modulator and a differential group-delay module, a microwave photonic notch filter is constructed. The relative time delay in reception of the signal at two separate antenna elements can be obtained by measuring the transmission notches over the signal spectra. The AOA is calculated from the relative time delay and the antenna spacing. The experiment results show that the measurement error is less than ±0.35 ps when the relative time delay changes from −14 to 16 ps.

A photonic microwave image rejection mixer (IRM) with large operating frequency range and high conversion efficiency is presented in this paper. The scheme is achieved by using a photonic microwave phase shifter, which is based on a polarization-division multiplexing Mach-Zehnder modulator (PDM-MZM). Thanks to the large operating frequency range of the photonic microwave phase shifter, the operating frequency of the proposed IRM can extend to 40 GHz. Besides, the system has high conversion efficiency, owing to the suppression of the optical carrier and application of balanced photodetector. To verify the scheme, an experiment is performed. Experimental results demonstrated large operating frequency range (5-40 GHz) and high image rejection ratio (40 dB) of the mixer. Compared with the conventional photonic microwave mixer, a 19-dB improvement of conversion efficiency is realized in the experiment.

A photonic approach to generate a phase-coded microwave waveform with frequency quadrupling is proposed and experimentally demonstrated in this paper. The system consists of a dual-parallel Mach-Zehnder modulator (DPMZM), a phase modulator (PM), a fiber Bragg grating (FBG), an optical coupler, and a photodetector. An optical carrier is modulated by a local oscillator (LO) in the DPMZM, and pure ±second-order sidebands are generated. Then, the two sidebands are separated by the FBG, and one of them is modulated by the coding signal through the PM. Both binary and quaternary phase-coded microwave signals with frequency quadrupling of the LO signal can be generated after detecting the recombined two sidebands. The proposed scheme is verified by experiments; phase-coded microwave waveforms at 24 and 12 GHz are generated by applying 6- and 3-GHz LO signals to the DPMZM, respectively. The pulse compression ratios of the generated waveforms are in good agreement with theoretical value.

A photonic triangular pulse generation method based on spectrum manipulation of phase-modulated signals is proposed and experimentally demonstrated. A light wave is first phase modulated by a sinusoidal signal to generate optical sidebands. Then, the optical spectra are manipulated by attenuating the optical carrier and one of the first-order sidebands with the same suppression ratio. By choosing a proper modulation index, a full-duty-cycle triangular pulse train with a repetition rate equal to the frequency of the drive signal can be generated. To improve the practical feasibility and the repetition-rate tunability, the spectrum manipulation is realized using a Sagnac loop and a fiber Bragg grating (FBG). In the experiment, four full-duty-cycle triangular pulse trains with different repetition rates (3-6 GHz) are successfully generated, and the repetition rate can be further improved if larger bandwidth measuring instruments are used. In addition to the large and tunable repetition rate, the proposed scheme also features the advantages of simple structure, low cost, and freedom from bias drift.

In this paper, a novel microwave photonic mixer based on a single integrated dual-drive dual-parallel Mach-Zehnder modulator (DD-DPMZM) is proposed. One submodulator is used to generate a single sideband (SSB) signal of the local oscillator, whereas the other submodulator is used to generate a double sideband signal of the radio-frequency signal. By adjusting the main dc bias of DD-DPMZM, we can suppress the optical carrier at the output of the DD-DPMZM. Mixed signals can be obtained after a photodiode. The structure features the advantages of high conversion efficiency and the elimination of dispersion-induced power fading. An experiment is carried out to verify the effectiveness of the scheme, and a significant improvement of 15.5 dB in conversion efficiency compared with the conventional photonic mixer is achieved. In addition, it avoids the influence of fiber dispersion. The proposed mixer is promising to find applications in future wideband wireless communication systems.

The dynamical response properties of photonic neuron based on vertical-cavity surface emitting lasers (VCSELs) subject to orthogonal polarized optical pulse injection stimuli have been numerically investigated. Based on the well-known spin flip model, we first reproduce some experimental findings of neuron-like dynamics in VCSELs, such as phasic spiking with a single abrupt pulse, and tonic spiking with multiple periodic pulses. Besides, we further go beyond in three directions and obtain several novel results. The operating parameter ranges corresponding to different neuron-like dynamics are identified by extensive bifurcation analysis. In addition, the effect of the time-varying pump current on the neuron-like dynamics for VCSELs under given optical injecting pulse strength is also discussed. For a given pump current, the spiking frequency dependence on the stimuli strength is further revealed in VCSELs with time-varying optical pulse injection. Such controllable neuron-like response dynamics and spiking frequency dependence in VCSELs are interesting and valuable for ultrafast photonic neuromorphic systems and neuron-inspired photonic information processing.