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.

Optical chaos generated by perturbing semiconductor lasers has been viewed, over recent decades, as an excellent entropy source for fast physical random bit generation (RBG) owing to its high bandwidth and large random fluctuations. However, most optical-chaos-based random bit generators perform their quantization process in the electrical domain using electrical analog-to-digital converters, so their real-time rates in a single channel are severely limited at the level of Gb/s due to the electronic bottleneck. Here, we propose and experimentally demonstrate an all-optical method for RBG where chaotic pulses are quantized into a physical random bit stream in the all-optical domain by means of a length of highly nonlinear fiber. In our proof-of-concept experiment, a 10-Gb/s random bit stream is successfully generated on-line using our method. Note that the single-channel real-time rate is limited only by the chaos bandwidth. Considering that the Kerr nonlinearity of silica fiber with an ultrafast response of few femtoseconds is exploited for composing the key part of quantizing laser chaos, this scheme thus may operate potentially at much higher real-time rates than 100 Gb/s provided that a chaotic entropy source of sufficient bandwidth is available.

针对带内全双工系统中的自干扰问题与有用信号的非线性失真问题，提出一种基于双偏振双驱动马赫曾德尔调制器的自干扰消除及线性度提升方案。包含有用信号和自干扰的接收信号注入该调制器的两个子双驱动马赫曾德尔调制器上臂的射频端口，构建的参考信号注入两个子调制器下臂的射频端口。两个子调制器被分别偏置在最大传输点和正交传输点，分别探测其输出光信号，得到两路电信号。当注入的参考信号和自干扰完全相同时，两路输出电信号中的自干扰可被完全消除。将这两路电信号采样后进行数字域联合处理，即可恢复出不含自干扰和非线性失真的有用信号。此外，提出了一种优化算法用于减少两路电信号功率不匹配导致的失真。通过仿真与实验验证该方案的可行性。实验结果表明，当有用信号为频率为10 MHz和12 MHz、功率为4 dBm的双音信号，自干扰为中心频率为11 MHz、符号率为4 Mbaud的正交相移键控信号时，该结构可以实现约25.6 dB的自干扰消除深度和17.3 dB的三阶交调抑制深度。

All-optical analog-to-digital conversion is a paramount issue in modern science. How to implement real-time and ultrafast quantization to optical pulses with different intensities in an all-optical domain is a central problem. Here, we report a real-time demonstration of an all-optical quantization scheme based on slicing the supercontinuum in a nonlinear fiber. In comparison with previous schemes through off-line analysis of the power of different optical spectral components in the supercontinuum, this, to the best of our knowledge, is the first demonstration of such functionality online in the time domain. Moreover, the extinction ratio among the quantized outputs can exceed 10 dB, which further confirms the feasibility of the proposed quantization scheme. The current 3 bit resolution in the proof-of-principle experiment is limited by the current experimental condition, but it can be expected to be greatly enhanced through improving both the spectral width of the generated supercontinuum and the number of filtering channels used.