We propose and experimentally demonstrate an ultraefficient broadband photonic channelizer. By polarization-division multiplexing the received signal and using dual-output Hartley image-reject receiving topology, 4N channels can be generated with only (N + 1)-line signal optical frequency comb (OFC) and N-line local oscillator (LO) OFC, and the frequency interval of the OFC is reduced to half of the typical value. With the use of the integrated dual-polarization coherent detection receiver (DP-CDR), the required quadrature optical hybrid (QOH) and the balanced photodetectors (BPDs) are reduced to half. The system size is reduced and stability is improved. Besides, assisted with a digital signal processor (DSP) algorithm, the IQ imbalance can be compensated, and approximately, ideal image rejection can be realized. A proof-of-concept experiment is carried out. A 2-14-GHz wideband signal is successfully divided into 12 channels with 1-GHz bandwidth by applying four-line signal OFC and three-line LO OFC. The image rejection ratio (IRR), channel isolation (CI), and spurious-free dynamic range (SFDR) are also measured and discussed.

Microwave photonic channelized receiver can break through the electronic bottleneck, improve the throughput of satellite payload, and is expected to be widely used in broadband satellite communications. To solve the self-interference problem in the full-duplex satellite relay system, a microwave photonic channelized receiver with a self-interference cancellation (SIC) function is proposed in this paper. The equal interval division of broadband radio frequency (RF) signals is realized through polarization multiplexing technology and optical frequency shifting technology. In addition, by constructing a reference interference signal and matching the delay and amplitude in the optical domain, the self-interference signal is eliminated to avoid the receiver blockage caused by interference leakage. Theoretical derivation and experiment research are carried out, and a wideband signal with 3-GHz bandwidth is down-converted to six sub-channels with a frequency range of 0.5 GHz–1 GHz. Under the single-tone test, the isolation between sub-channels exceeds 31 dB, and the SIC depth exceeds 40 dB. When the sub-channels carry the 16quadrature amplitude modulation (QAM) signals with the bandwidth of 50 MHz, the SIC depth over 26 dB is achieved, and the error vector magnitude (EVM) is 7.6%. Under the two-tone test, the SFDR of the sub-channel is 93.5 dB.Hz ^2/3 .

Doppler frequency shift (DFS) and angle of arrival (AOA) measurements play a crucial role in modern radar, aviation, and satellite communication systems. Rydberg atom-based receivers are renowned for the high sensitivity, wide operating frequency range, and immunity to electromagnetic interference in microwave electric field sensing. In this work, the concept of electromagnetically induced transparency (EIT) with Rydberg atoms, along with heterodyne mixing techniques, is employed to accurately measure both the DFS and AOA of microwave field within a unified experimental system. The proposed scheme utilizes the dual-coupled beams in the Rydberg atom vapor cell to reduce experimental errors and improve the measurement accuracy. The experimental results indicate that within the frequency measurement range from 11 to 18 GHz, the experimental error in measuring the DFS of different Rydberg states is within ±0.5 Hz, showcasing the wideband tunability of the system. Moreover, the AOA measurement for the echo signal reveals that the measurement error is less than 0.5° within the range from −30° to 35°. This research shows the first instance of simultaneously measuring DFS and AOA within the same Rydberg atom system. Additionally, by introducing the concept of “relative frequency zero point” in DFS measurement for the first time, the differentiation of the direction of the DFS can be identified. Furthermore, the accuracy of AOA measurement based on Rydberg atoms has been further improved in this research. Overall, this research provides a novel approach for measuring DFS and AOA using Rydberg atomic system.

In order to meet the requirements of large instantaneous bandwidth, wide operating frequency range, large dynamic range, and anti-interference for microwave parameter measurement in the new generation radar system and real-time signal processing system, a microwave photonic Doppler frequency shift (DFS) and angle of arrival (AOA) measurement scheme based on Mach–Zehnder modulator (MZM) and acousto-optic modulator (AOM) is proposed in this article. The designed structure can clearly identify the direction of the DFS and avoid the intermodulation distortion and low-frequency interference. In addition, the upper and lower optical sidebands are fully utilized to effectively avoid the frequency error caused by the AOM driver module and improve the measurement accuracy of the system. In the experiment, the error of the microwave DFS at an ultrawide operation frequency from 6 to 36 GHz is between ±0.15 Hz with a clear direction. The micro-DFS (mDFS) measurement is also carried out to demonstrate the advantage of low-frequency DFS measurement. It is also verified that the phase difference error is less than 1° in the AOA measurement experiment. The proposed scheme has advantages such as multifunction and anti-interference, thus having great application prospects.

Radar target simulator (RTS) is extensively used in the development, debugging, and operation of automotive millimeter-wave radar systems. However, the performance of the traditional RTS based on digital radio frequency memory (DRFM) is limited by the complexity and spurious of radio frequency (RF) front end, the sampling rate of the analog-to-digital converter (ADC), and inherent delays in digital signal processing, which is hard to meet the urgent needs of wide bandwidth, low spurious distortion, high precision, and low delay. To solve this problem, a simple, multiband universal, high precision, and low-spur photonic RTS photonic RTS based on all-optical IQ upconverter is proposed. The experiment shows that the moving direction can be switched by flexible control of up-and down-frequency shifts, and accurate simulation of the target with different speeds can be achieved by a large-range-tunable Doppler frequency shift. In addition, the distance of the target can be flexibly tuned by optical delay, and the radar scattering cross section (RCS) can be simulated by wide-range power attenuation. Due to all-optical operation, the simulator has the advantages of adjustable working frequency ( L – K band), large modulation bandwidth (dc to gigahertz level), and high spurious suppression ( $>$ 30 dB). Moreover, the amplitude and phase of the generated simulated signal can also be adjusted, which is of great value in electronic warfare jamming and forwarding systems.

A microwave photonic instantaneous frequency and angle of arrival (AOA) measurement method based on a Sagnac loop is proposed and demonstrated in this paper. By establishing a monotonic relationship between the phase difference and the direct current (dc) amplitude, an amplitude comparison function (ACF) is constructed to achieve AOA measurement. Meanwhile, the instantaneous frequency measurement (IFM) is achieved by introducing optical delay. By adjusting the optical delay, the scheme can not only tune the frequency measurement range but also increase the measurement accuracy. The experiment results prove that the phase difference error of the AOA measurement is less than 1 degree, and the IFM measurement error in the frequency range of 0.5-36 GHz is ±0.2 GHz. The scheme has the characteristics of multi-function, simple structure and large bandwidth, it has a great competitive advantage in the future electronic applications.