A microwave photonic subsampling digital receiver (MPSDR) is proposed and experimentally demonstrated for target detection with a sampling rate of 10 MSa/s. Stepped and pseudo-random frequency-hopping signals with frequencies across the K band are both used for target detection and can be captured by the MPSDR. The range profiles of the targets are then derived using a compressed sensing algorithm, and precise target position estimation is achieved by changing the measurement position of the antenna pair. The results demonstrate that the estimation accuracy remains comparable even when the pseudo-random frequency-hopping signal utilizes only 12.5% of the frequency points required by the stepped frequency-hopping signal. This highlights the efficiency and potential of the proposed MPSDR in processing complex signals while maintaining high accuracy.

The acousto-optic modulator (AOM) plays an important role in heterodyne interferometric sensing, and it is always regarded as an ideal optical frequency shifter. In this paper, we compare the effects of its residual zero-order diffraction in different AOM configurations. The theory shows that using double AOMs can effectively solve the same frequency crosstalk problem caused by zero-order perturbation without worsening the noise floor. The interferometer employs a photonics-assisted mmWave composed of two comb lines from an electro-optical frequency comb as the optical source, which results in the laser frequency noise cancellation in the difference. Experimentally, a dither with a peak-to-peak value of 0.15 ps in the single AOM configuration can be effectively suppressed to below the noise floor through double AOMs, which shows the potential to achieve high sensing accuracy.

In this paper, we propose a photonic terahertz (THz) continuous-wave computed tomography (CT) system employing an optical frequency comb and specialized imaging algorithms. Our work leverages the system to offer unique advantages in detecting and analyzing samples that are challenging for traditional 2D scanning systems. Our experimental results, operating at 330 GHz, reach an exceptionally low amplitude standard deviation of 0.016 mV. Additionally, the proposed system performs nondestructive CT detection with a 0.5 mm error margin and obtains enhanced image quality, showing its great promise for implementing THz-CT imaging with high robustness and resolution.

We demonstrated a fiber–terahertz (THz)–fiber communication system at the D-band based on full photonic conversions, exploiting a modified unitraveling-carrier photodiode (MUTC-PD) module to achieve optical-to-THz conversion at the transmitter end and an ultrabroadband packaged thin-film lithium niobate Mach–Zehnder modulator (MZM) to convert the THz signal to the optical signal at the receiver end. This system successfully realized the transmission of 33-Gbaud 16-quadrature amplitude modulation (QAM) and 31-Gbaud probabilistic shaping-64-QAM signals through 10-km standard single-mode fiber (SSMF), 0.6-m wireless distance, and the subsequent 5-km SSMF, achieving net data rates of 116.03 and 123.72 Gbps, respectively.

We propose a novel automatic phase-matching method for generating optical frequency combs using cascaded electro-optic modulators. By analyzing the power changes of different spectral lines, our method enables real-time monitoring and dynamic adjustment to achieve precise phase matching. Experiments have confirmed the fast phase matching and the adjustable spacing of a flat electro-optic frequency comb and its long-term stability. This method provides flexible and efficient light source solutions for optical communications, spectral analysis, and optical measurements.

We propose and experimentally demonstrate a photonic method for wideband multipath self-interference cancellation using a silicon photonic modulator chip. The chip generates phase-inverted reference signals by leveraging the opposite phase between optical sidebands. Effectively managing amplitude and phase imbalances between self-interference and reference signals, the approach rectifies discrepancies through consistent chip manufacturing and packaging processes. Employing photonic multi-dimensional multiplexing, including wavelength and polarization, enables the acquisition of multiple reference signals. Experimental results show multipath cancellation depths of 25.53 dB and 23.81 dB for bandwidths of 500 MHz and 1 GHz, achieved by superimposing 2-path reference signals.

This paper reports a photonics-assisted millimeter-wave (mm-wave) joint radar jamming and secure communication system constructed through a photonic upconversion technique. In the experiments, a 30 GHz constant envelope linear frequency-modulated orthogonal frequency division modulation (CE-LFM-OFDM) signal with an instantaneous bandwidth of 1 GHz is synthesized by encoding 1 GBaud encrypted 16-quadrature amplitude modulation (16-QAM) OFDM signal. The velocity deception jamming is achieved with a spurious suppression ratio over 30 dB. Furthermore, we efficiently execute range deception jamming with a time shift of 10 ns. Simultaneously, the encrypted 16-QAM OFDM signal is successfully transmitted over a 1.2 m wireless link, with a data rate of 4 Gbit/s.

Photonic microwave harmonic down-converters (PMHDCs) based on self-oscillation optical frequency combs (OFCs) are interesting because of their broad bandwidth compared with plain optoelectronic oscillators. In this paper, a high-efficiency and flexible PMHDC is proposed and demonstrated. The properties of the OFC, such as the carrier-to-noise ratio (CNR), bandwidth and free spectral range (FSR), and the influence of optical injection, are investigated. The broadband OFC provides a frequency tunable and high-quality local oscillation (LO), which guarantees flexible down-conversion for the radio frequency (RF) signal. The sideband selective amplification (SSA) effect not only improves the conversion efficiency but also promotes single-sideband modulation. The conversion range can reach 100 GHz. The 12–40 GHz RF signal can be down-converted to intermediate frequency (IF) signals with a high conversion efficiency of 14.9 dB. The fixed 40-GHz RF signal is flexibly down-converted to an IF signal with the frequency from 55.4 to 2129.4 MHz. The phase noise of an IF signal at a frequency offset of 10 kHz is the same as that of the input RF signal. The PMHDC shows great performance and will find applications in radio-over-fiber (RoF) networks, electronic warfare receivers, avionics, and wireless communication systems.

We propose a method for optimizing the phase stability of microwave signal transmission over long distances. First, the design of the photon link was modified to reduce the radio frequency (RF) signal’s baseline noise and increase power. Second, a low-noise driver circuit was developed for a two-section distributed feedback (DFB) laser designed using reconstruction equivalent chirp (REC) technology to create an ultra-stable laser, and its performance was characterized through linewidth data. Test results indicate that the DFB laser achieved narrower linewidth, improving system phase stability. When an injection current (30 mA) is applied to the reflection section of the two-section DFB laser, the laser linewidth will be narrower (1.38 MHz), further enhancing the system’s phase transmission stability. At a 1 Hz offset frequency, a residual phase noise of -88.65 dBc/Hz is obtained. The short-term stability with an averaging time of 1 s is 1.60 × 10-14, and the long-term stability over a testing time of 60,000 s is 3.41 × 10-18. Even after incorporating temperature variations, the long-term stability reaches 8.37 × 10-18 at 22 h.

An approach for frequency division of an optical pulse train (OPT) based on an optoelectronic oscillator (OEO) is proposed and experimentally demonstrated. When the OPT is injected into the OEO, a microwave signal with a frequency equaling fractional multiples of the repetition rate of the OPT is generated. This signal is then fed back to the OEO, maintaining its oscillation, while simultaneously serving as the control signal of a Mach–Zehnder modulator (MZM) in the OEO. The MZM acts as an optical switch, permitting specific pulses to pass through while blocking others. As a result, the repetition rate of the OPT is manipulated. A proof-of-concept experiment is carried out. Frequency division factors of 2 and 3 are successfully achieved. The phase noises of the OPT before and after the frequency division are investigated. Compared to previously reported systems, no external microwave source and sophisticated synchronization structure are needed.

This paper experimentally demonstrates a distributed photonics-based W-band integrated sensing and communication (ISAC) system, in which radar sensing can aid the communication links in alignment and data rate estimation. As a proof-of-concept, the ISAC system locates the users, guides the alignment, and sets a communication link with the estimated highest data rate. A peak net data rate of 68.6 Gbit/s and a target sensing with a less-than-1-cm error and a sub-2-cm resolution have been tested over a 10-km fiber and a 1.15-m free space transmission in the photonics-based W-band ISAC system. The achievable net data rates of the users at different locations estimated by sensing are experimentally verified.

Electromagnetic topological chiral edge states mimicking the quantum Hall effect have attracted a great deal of attention due to their unique features of free backscattering and immunity against sharp bends and defects. However, the matching techniques between classical waveguides and the topological one-way waveguide deserve more attention for real-world applications. In this paper, a highly efficient conversion structure between a classical rectangular waveguide and a topological one-way waveguide is proposed and demonstrated at the microwave frequency, which efficiently converts classical guided waves to topological one-way edge states. A tapered transition is designed to match both the momentum and impedance of the classical guided waves and the topological one-way edge states. With the conversion structure, the waves generated by a point excitation source can be coupled to the topological one-way waveguide with very high coupling efficiency, which can ensure high transmission of the whole system (i.e., from the source and the receiver). Simulation and measurement results demonstrate the proposed method. This investigation is beneficial to the applications of topological one-way waveguides and opens up a new avenue for advanced topological and classical integrated functional devices and systems.

We propose and experimentally demonstrate the programmable photonic radio frequency (RF) filters based on an integrated Fabry–Pérot laser with a saturable absorber (FP-SA). Owing to the high output power and the relative flatness spectrum of the FP-SA laser, only a waveshaper and an erbium-doped fiber amplifier (EDFA) were needed, which can greatly reduce the complexity of the system. The sinc filter employed 87 taps, representing a record-high tap number and resulting in a 3-dB bandwidth of 0.27 GHz and a quality factor of 148. Furthermore, Gaussian apodization enabled the out-of-band rejection of the filter to reach 34 dB and the center frequency to be finely tuned over a wide range, spanning from 4 to 14 GHz. These results indicate that the proposed scheme could provide a promising guideline for the photonic RF filters that demand both high reconfigurability and greatly reduced size and complexity.

In this Letter, we demonstrate the transmission of fifth-generation new radio (5G NR) signals over a fiber-millimeter-wave (mmWave)-fiber mobile fronthaul system in the 75–110 GHz band for an ultra-dense small cell network. The system employs a simple all-optical conversion technology, including mmWave signal generation using an optical heterodyne and a photonics-enabled receiver based on different modulator schemes. As a proof-of-concept demonstration, we successfully transmit 400 MHz 64QAM/256QAM at 3.5 and 4.9 GHz. The proposed system can provide a simple solution for facilitating the deployment of ultra-dense small cells in high-frequency bands for 5G mmWave/intermediate-frequency-over-fiber networks.

The stable long-distance transmission of radio-frequency (RF) signals holds significant importance from various aspects, including the comparison of optical frequency standards, remote monitoring and control, scientific research and experiments, and RF spectrum management. We demonstrate a scheme where an ultrastable frequency signal was transmitted over a 50 km coiled fiber. The optical RF signal is generated using a two-section distributed feedback (DFB) laser for direct modulation based on the reconstruction equivalent chirp (REC) technique. The 3-dB modulation bandwidth of the two-section DFB laser is 18 GHz and the residual phase noise of -122.87 dBc/Hz is achieved at 10-Hz offset frequency. We report a short-term stability of 1.62×10-14 at an average time of 1 s and a long-term stability of 6.55×10-18 at the measurement time of 62,000 s when applying current to the front section of the DFB laser. By applying power to both sections, the stability of the system improves to 4.42×10-18 within a testing period of 56,737 s. Despite applying temperature variations to the transmission link, long-term stability of 8.63×10-18 at 23.9 h can still be achieved.

A sub-Nyquist radar receiver based on photonics-assisted compressed sensing is proposed. Cascaded dictionaries are applied to extract the delay and the Doppler frequency of the echo signals, which do not need to accumulate multiple echo periods and can achieve better Doppler accuracy. An experiment is performed. Radar echoes with different delays and Doppler frequencies are undersampled and successfully reconstructed to obtain the delay and Doppler information of the targets. Experimental results show that the average reconstruction error of the Doppler frequency is 5.33 kHz using an 8-μs radar signal under the compression ratio of 5. The proposed method provides a promising solution for the sub-Nyquist radar receiver.

High accuracy and time resolution optical transfer delay (OTD) measurement is highly desired in many multi-path applications, such as optical true-time-delay-based array systems and distributed optical sensors. However, the time resolution is usually limited by the frequency range of the probe signal in frequency-multiplexed OTD measurement techniques. Here, we proposed a time-resolution enhanced OTD measurement method based on incoherent optical frequency domain reflectometry (I-OFDR), where an adaptive filter is designed to suppress the spectral leakage from other paths to break the resolution limitation. A weighted least square (WLS) cost function is first established, and then an iteration approach is used to minimize the cost function. Finally, the appropriate filter parameter is obtained according to the convergence results. In a proof-of-concept experiment, the time-domain response of two optical links with a length difference of 900 ps is successfully estimated by applying a probe signal with a bandwidth of 400 MHz. The time resolution is improved by 2.78 times compared to the theoretical resolution limit of the inverse discrete Fourier transform (iDFT) algorithm. In addition, the OTD measurement error is below ±0.8 ps. The proposed algorithm provides a novel way to improve the measurement resolution without applying a probe signal with a large bandwidth, avoiding measurement errors induced by the dispersion effect.

The terahertz photonics technique has bright application prospects in future sixth-generation (6G) broadband communication. In this study, we have experimentally demonstrated a photonics-assisted record-breaking net bit rate of 417 Gbit/s per wavelength signals delivery in a fiber-wireless converged communication system supported by advanced digital-signal-processing (DSP) algorithms and a polarization multiplexing-based multiple-input multiple-output (MIMO) scheme. In the experiment, up to 60 GBaud (480 Gbit/s) polarization-division-multiplexing 16-ary quadrature-amplitude-modulation (PDM-16QAM) signals are transmitted over 20 km fibers and 3 m wireless 2×2 MIMO links at 318 GHz with the bit error rate (BER) under 1.56×10-2. It is the first demonstration to our knowledge of signals delivery exceeding 400 Gbit/s per wavelength in a photonics-assisted fiber-wireless converged 2×2 MIMO communication system.

We experimentally demonstrated the use of intelligent impairment equalization (IIE) for microwave downconversion link linearization in noncooperative systems. Such an equalizer is realized based on an artificial neural network (ANN). Once the training process is completed, the inverse link transfer function can be determined. With the inverse transformation for the detected signal after transmission, the third-order intermodulation distortion components are suppressed significantly without requiring any prior information from an input RF signal. Furthermore, fast training speed is achieved, since the configuration of ANN-based equalizer is simple. Experimental results show that the spurious-free dynamic range of the proposed link is improved to 106.5 dB · Hz2/3, which is 11.3 dB higher than that of a link without IIE. Meanwhile, the training epochs reduce to only five, which has the potential to meet the practical engineering requirement.

Recently, wireless communication capacity has been witnessing unprecedented growth. Benefits from the optoelectronic components with large bandwidth, photonics-assisted terahertz (THz) communication links have been extensively developed to accommodate the upcoming wireless transmission with a high data rate. However, limited by the available signal-to-noise ratio and THz component bandwidth, single-lane transmission of beyond 100 Gbit/s data rate using a single pair of THz transceivers is still very challenging. In this study, a multicarrier THz photonic wireless communication link in the 300 GHz band is proposed and experimentally demonstrated. Enabled by subcarrier multiplexing, spectrally efficient modulation format, well-tailored digital signal processing routine, and broadband THz transceivers, a line rate of 72 Gbit/s over a wireless distance of 30 m is successfully demonstrated, resulting in a total net transmission capacity of up to 202.5 Gbit/s. The single-lane transmission of beyond 200 Gbit/s overall data rate with a single pair of transceivers at 300 GHz is considered a significant step toward a viable photonics-assisted solution for the next-generation information and communication technology (ICT) infrastructure.

We focus on photonic generation and transmission of microwave signals in this work. Based on dual-pumped stimulated Brillouin scattering, a single-sideband (SSB) optical signal with high sideband rejection ratio is obtained. Combined with a phase-modulated optical carrier, an arbitrarily phase coded microwave signal is generated after photoelectric conversion. The SSB modulation can eliminate the fiber-dispersion-induced power dispersion naturally, and the phase modulation of the optical carrier can achieve arbitrary phase encoding and suppress background noise. The proposed scheme can achieve both generation and anti-dispersion transmission of arbitrarily phase coded signals simultaneously, which is suitable for one-to-multi long-distance radar networking.

This work presents experimental results of Rabi antenna characteristics using the coupled line microstrip circuit. It was constructed by a modified coupled line microstrip four-port network, which is known as an add-drop multiplexer. The driven AC input enters the device via an input port using the suitable frequency and coupled line microstrip ring radius. The multi-level system is generated by a wave-particle aspect before the two-level system is achieved. At the resonance, the transitions of the states induce the energy called whispering gallery mode (WGM) at the circuit center, which is the squeezed energy. The generated electron oscillation within the WGM envelope oscillated by the frequency is known as the Rabi frequency. By the successive filtering with continuous AC input via the selected port, the electron cloud warp speed can be generated and achieved inside the two-level transition. The constructed microstrip ring radius is 25 mm, and the experimental results of the Rabi antenna characteristics are in good agreement with the simulation results. The obtained resonant antenna oscillation frequency is 2.103 GHz. The electron cloud warp speed of 1.100c and time dilation of 0.006 µs are obtained.

A compact and cost-effective photonic approach for generating switchable multi-format linearly chirped signals is proposed and experimentally demonstrated. The core component is a dual-drive Mach–Zehnder modulator driven by a coding sequence and a linearly chirped waveform. By properly setting the amplitudes of the coding sequence, a linearly chirped signal with different formats, including the frequency shift keying (FSK), phase shift keying (PSK), dual-band PSK, and FSK/PSK modulation formats, can be generated. Experiments are conducted to verify the feasibility of the proposed scheme. Linearly chirped signals with the above four formats are successfully generated. The scheme features multiple formats and high tunability based on a compact structure, which has potential applications in modern multifunctional systems.

We present a discovery of an unusual unidirectionally rotating windmill scattering of electromagnetic waves by a magnetized gyromagnetic cylinder via an analytical theory for rigorous solution to fields and charges and an understanding of the underlying mathematical and physical mechanisms. Mathematically, the generation of nonzero off-diagonal components can break the symmetry of forward and backward scattering coefficients, producing unidirectional windmill scattering. Physically, this windmill scattering originates from the nonreciprocal unidirectional rotation of polarized magnetic charges on the surface of a magnetized gyromagnetic cylinder, which drives the scattering field to radiate outward in the radial direction and unidirectionally emit in the tangential direction. Interestingly, the unidirectional electromagnetic windmill scattering is insensitive to the excitation direction. Moreover, we also discuss the size dependence of unidirectional windmill scattering by calculating the scattering spectra of the gyromagnetic cylinder. These results are helpful for exploring and understanding novel interactions between electromagnetic waves and gyromagnetic materials or structures and offer deep insights for comprehending topological photonic states in gyromagnetic systems from the aspect of fundamental classical electrodynamics and electromagnetics.

Weak RF signal detection with high resolution and no blind zone based on directly modulated multi-mode optoelectronic oscillation has been proposed. The high-sensitivity optical modulators and optical filters are avoided because multi-mode oscillation is obtained based on directly modulating the semiconductor laser at the relaxation oscillation frequency. For the directly modulated optoelectronic oscillator, the detection characteristics such as gain for the RF signal, resolution, noise floor, and sensitivity are firstly analyzed. The experimental results are consistent with the simulated results. For the RF signal of unknown frequency, it can be detected out and amplified by tuning the bias current and delay time of the loop. There is no blind zone within 1–4.5 GHz. The system provides a maximum gain of 17.88 dB for the low-power RF signal. The sensitivity of the system can reach as high as -95 dBm. The properties such as gain dynamic range and power stability are also investigated. The system has potential for weak RF signal detection, especially for the RF signal with unknown frequency.

We experimentally built a photonics-aided long-distance large-capacity millimeter-wave wireless transmission system and demonstrated a delivery of 40 Gbit/s W-band 16-ary quadrature amplitude modulation (QAM) signal over 4600 m wireless distance at 88.5 GHz. Advanced offline digital signal processing algorithms are proposed and employed for signal recovery, which makes the bit-error ratio under 2.4×10-2. To the best of our knowledge, this is the first field-trial demonstration of >4 km W-band 16QAM signal transmission, and the result achieves a record-breaking product of wireless transmission capacity and distance, i.e., 184 (Gbit/s)·km, for high-speed and long-distance W-band wireless communication.

Transient response of an erbium-doped fiber amplifier (EDFA) is studied in an externally-modulated analog link. Double tones represented as transmitted radio frequency and dither signals are introduced. Extra modulation is generated owing to the EDFA’s transient response caused by a low-frequency dither signal. Therefore, the parasitic modulation is superposed to the output signals and may significantly affect in-band electrical spectra. Analytical and numerical solutions are both given, which agree well with experimental results. This work indicates that a suitable dither signal should be selected to maximize the carrier to intermodulation ratio. In-band spurious free dynamic range is optimized in the meantime.

A microwave-chip-based coherent multi-frequency RF driver is developed for a channel-interleaved photonic analog-to-digital converter (PADC) system, which comprises a multi-class optical demultiplexer and supports a sampling speed of 40 GSa/s. The generated signals from the RF driver are adjustable in both amplitude and phase. We analyze the relationship between the characteristics of the generated RF driver signals and the demultiplexing performance in theory based on the optical signal-to-distortion ratio (OSDR). It is the most effective parameter to evaluate the performance of the demultiplexer in a PADC system without an electronic analog-to-digital converter. By precisely adjusting the amplitude and phase of signals, the OSDR is optimized. The results verify the compatibility between the RF driver and the PADC system.

Radio frequency (RF) self-interference is a key issue for the application of in-band full-duplex communication in beyond fifth generation and sixth generation communications. Compared with electronic technology, photonic technology has the advantages of wide bandwidth and high tuning precision, exhibiting great potential to realize high interference cancellation depth over broad band. In this paper, a comprehensive overview of photonic enabled RF self-interference cancellation (SIC) is presented. The operation principle of photonic RF SIC is introduced, and the advances in implementing photonic RF SIC according to the realization mechanism of phase reversal are summarized. For further realistic applications, the multipath RF SIC and the integrated photonic RF SIC are also surveyed. Finally, the challenges and opportunities of photonic RF SIC technology are discussed.

We demonstrate a chip-scale scheme of Brillouin instantaneous frequency measurement (IFM) in a CMOS-compatible doped silica waveguide chip. In the chip-scale Brillouin IFM scheme, the frequency-to-power mapping process is achieved by one-shot detection without additional time averaging and implemented by lock-in amplification, which successfully detects the Brillouin gain of the doped silica waveguide chip in the time domain. A Costas frequency modulated signal ranging from 8 GHz to 9 GHz is experimentally measured, and the frequency measurement errors are maintained within 58 MHz.

The analog photonics link (APL) is widely used in microwave photonics. However, in wideband and multi-carrier systems, the third inter-modulation distortion (IMD3) and cross-modulation distortion (XMD) will jointly limit the spurious-free dynamic range (SFDR) of links. In this paper, we experimentally present a linearized wideband and multi-carrier APL, in which the IMD3 and XMD are mitigated simultaneously by using artificial neural networks with transfer learning (TL-ANN). In this experiment, with different artificial neural networks, which are trained with the knowledge obtained from the two- or three-sub-carrier system, the IMD3 and XMD are suppressed by 21.71 dB and 11.11 dB or 22.38 dB and 16.73 dB, and the SFDR is improved by 13.4 dB or 14.3 dB, respectively. Meanwhile, compared with previous studies, this method could reduce the training time and training epochs to 16% and 25%.

An approach to generate high-speed and wideband frequency shift keying (FSK) signals based on carrier phase-shifted double sideband (CPS-DSB) modulation is proposed and experimentally validated. The core part of the scheme is a pair of cascaded polarization-sensitive LiNbO3 Mach–Zehnder modulators and phase modulators, whose polarization directions of the principal axes are mutually orthogonal to each other. A proof-of-concept experiment is carried out, where a 0.5 Gb/s FSK signal with the carrier frequencies of 4 and 8 GHz and a 1 Gb/s FSK signal with the carrier frequencies of 8 and 16 GHz are generated successfully.

We propose a photonics-assisted equivalent frequency sampling (EFS) method to analyze the instantaneous frequency of broadband linearly frequency modulated (LFM) microwave signals. The proposed EFS method is implemented by a photonic scanning receiver, which is operated with a frequency scanning rate slightly different from the repetition rate of the LFM signals. Compared with the broadband LFM signal analysis based on temporal sampling, the proposed method avoids the use of high-speed analog to digital converters, and the instantaneous frequency acquisition realized by frequency-to-time mapping is also simplified since real-time Fourier transformation is not required. Feasibility of the proposed method is verified through an experiment, in which frequency analysis of Kα-band LFM signals with a bandwidth up to 3 GHz is demonstrated with a moderate sampling rate of 100 MSa/s. The proposed method is highly demanded for analyzing the instantaneous frequency of broadband LFM signals used in radar and electronic warfare systems.

A photonic approach to concurrently measure the angle-of-arrival (AOA) and the chirp rate of a linear frequency modulated (LFM) signal is proposed and experimentally demonstrated. The measurement is achieved by estimating the differential frequency of a two-tone signal output by a dual-parallel Mach–Zehnder modulator and an additional asymmetry Mach–Zehnder interferometer. Experiments show that the AOA and the chirp rate are measured simultaneously, with an AOA measurement error of ±0.1° at an signal-to-noise ratio (SNR) of 9.6 dB. When the SNR is -10.4 dB, the AOA error is ±1.3°, and the chirp rate, measured as 210.2±1.5 Hz/ps, has a standard deviation of 0.7%. The measured chirp rate agrees well with the real LFM signal.

We demonstrate a photonic architecture to enable the separation of ultra-wideband signals. The architecture consists of a channel-interleaved photonic analog-to-digital converter (PADC) and a dilated fully convolutional network (DFCN). The aim of the PADC is to perform ultra-wideband signal acquisition, which introduces the mixing of signals between different frequency bands. To alleviate the interference among wideband signals, the DFCN is applied to reconstruct the waveform of the target signal from the ultra-wideband mixed signals in the time domain. The channel-interleaved PADC provides a wide spectrum reception capability. Relying on the DFCN reconstruction algorithm, the ultra-wideband signals, which are originally mixed up, are effectively separated. Additionally, experimental results show that the DFCN reconstruction algorithm improves the average bit error rate by nearly three orders of magnitude compared with that without the algorithm.