提出了一种能够实现任意滤波形状的高分辨率可重构微波光子滤波器方案。利用可编程光滤波器完成抽头系数的独立灵活配置，配合使用相干探测技术实现滤波器的正负抽头，从而可以完成滤波形状的任意可重构。研究表明一个大梳齿数量的平坦光频梳被作为光源可提高抽头数量，从而实现高分辨率的滤波器的重构。除此之外，通过预先引入色散，响应中的杂散也被有效地抑制。经仿真验证，该滤波器具有93 MHz的高分辨率，杂散抑制40 dB以上，创新性地构造了具有不同中心频率的低通、带通、高通、带阻滤波器，以及矩形、高斯形、sinc形等任意滤波形状，对于后续微波光子滤波器的研究起到了引导性作用。

In this paper, we propose and experimentally demonstrate a joint shaping technique to improve the performance of a low-resolution transmission system for the first time, to the best of our knowledge. The joint shaping technique combines probabilistic shaping (PS) and error feedback noise shaping (EFNS). In the 40-Gbaud intensity-modulation direct-detection (IM/DD) experimental transmission system, a bit-error-rate (BER) of 3.8×10-3 can be achieved easily with the joint shaping at the physical number of bits (PNOB) of 3. In the 30-Gbaud dual polarization (DP) coherent experimental transmission system, a BER below 1×10-3 is easily obtained with a 3-bit quantizer by using joint shaping. The optimization of the shaping degree is also analyzed.

Temporal magnification is an emerging technology for the observation of single-shot optical signals with irregular and ultrafast dynamics, which exceed the speed, precision, and record length of conventional digitizers. Conventional temporal magnification schemes suffer from transmission delay and large volume of dispersive elements. Because only the signal envelope can be magnified in the dispersion-based schemes, real-time full-field (phase and amplitude) measurement for a complex ultrafast optical signal remains an open challenge. Here, a bandwidth-compressed temporal magnification scheme for low-latency full-field measurements of ultrafast dynamics is proposed. Unlike the dispersion-based schemes, temporal magnification of a complex optical signal is achieved by bandwidth compression. The bandwidth is coherently compressed by the Vernier effect relying on the detuned free spectral range of a periodic optical filter and time lens. Experimentally, a temporal magnification factor of 224 is realized, and full-field measurements for picosecond pulses are demonstrated. The proposal eliminates the dependence on dispersive elements and shows great potential in integration, which may pave a new path toward full-field measurement for nonrepetitive and statistically rare signals.

随着现代通信系统的发展，宽带和高频微波射频信号在雷达，通信和信号处理等领域的应用越来越广泛。基于微波光子信道化技术，文中通过两个自由频谱范围不同的光学频梳，实现了超宽带射频信号的信道化合成。在信道化合成系统中，多个独立的窄带信号输入各个信道进行上变频，并在多外差探测中被重组成为一个具有连续频谱的宽带射频信号。在多外差探测中，干扰抑制技术的使用提高了合成射频信号可达到的最高频率。在实验中，合成了一个覆盖频率范围8.4~12.4 GHz，瞬时带宽为4 GHz的宽带射频信号。实验结果显示，干扰的抑制率达到了21 dB，表明干扰抑制技术的使用提高了输出信号的最高频率的同时有效地提高了频谱利用率。

The multimode fiber (MMF) has great potential to transmit high-resolution images with less invasive methods in endoscopy due to its large number of spatial modes and small core diameter. However, spatial modes crosstalk will inevitably occur in MMFs, which makes the received images become speckles. A conditional generative adversarial network (GAN) composed of a generator and a discriminator was utilized to reconstruct the received speckles. We conduct an MMF imaging experimental system of transmitting over 1 m MMF with a 50 μm core. Compared with the conventional method of U-net, this conditional GAN could reconstruct images with fewer training datasets to achieve the same performance and shows higher feature extraction capability.

A full-band direct-conversion receiver using a microwave photonic in-phase and quadrature (I/Q) mixer is proposed and experimentally evaluated in terms of radio frequency (RF) range, port isolation, phase imbalance, conversion gain, noise figure, spurious-free dynamic range, and error vector magnitude. The proposed microwave photonic I/Q mixer shows significant advantages in local oscillator leakage and I/Q phase imbalance over entire RF bands, which are recognized as major drawbacks of conventional direct-conversion receivers.

In this Letter, we experimentally demonstrate a full-duplex transmission system of IEEE 802.11ac-compliant multiple-input multiple-output (MIMO) signals over a 2-km 7-core fiber for in-building wireless local-area network (WLAN) distributed antenna systems. For full-duplex 3×3 MIMO demonstration, the crosstalk impacts of both fiber-transmission-only and optic-wireless transmission situation are evaluated. The results indicate that the impact of crosstalk on radio-over-fiber (ROF) link performance is not significant and the quality of the cascaded multi-core fiber and wireless channel is mainly determined by the wireless part. To further improve the system capacity, polarization multiplexing (PolMux) technology is employed to achieve a full-duplex 6×6 MIMO over a single 7-core fiber. Although employing the PolMux method will slightly decrease the EVM and condition number performance as opposed to a non-PolMux MCF system, it is still a competitive solution in large optical connection demand scenarios that require a low cost.

We propose a high-Q photonic-electronic hybrid cavity for single-longitudinal-mode narrow-linewidth oscillation, where part of the cavity is in the radio frequency (RF) domain by a pair of frequency conversions. In the RF part, we can easily achieve MHz filtering and a large delay by inserting an electronic filter. In mathematics, we prove that the frequency conversion pair and electronic filter in between can be equivalent to a high-Q optical filter cascaded low-noise optical amplifier as a whole. Finally, the 20-dB bandwidth of oscillation is 1/20 of that of an optical local oscillator, and the maximum phase noise suppression can reach 65 dB.