针对双波长激光器间距精细调谐的需求，基于正方形微腔的模场分布，设计了中心及四个角区电流注入窗口的正方形微腔激光器。利用有限元法对提出的结构进行分析，发现改变腔体折射率分布差，可以调控基横模和一阶横模的波长间距。基于半导体平面加工工艺成功制备了边长为30 μm的非均匀注入正方形微腔激光器。当注入电流从42 mA增加到53 mA时，该激光器的波长间隔从0.18 nm减小到0.1 nm，强度比小于4 dB。除此之外，继续增加电流，由于双模间隔的进一步减小，出现了明显的单周期振荡现象。

We propose and demonstrate the generation of wideband chaos based on a dual-mode microsquare semiconductor laser with optical feedback. By adjusting the dual-mode intensity ratio and the feedback strength, wideband chaos covering more than 50 GHz in the RF spectrum is achieved. The standard and effective bandwidths of the chaotic signal are 31.3 GHz and 30.7 GHz with the flatness of 8.3 dB and 6.1 dB, respectively.

The generation of high-repetition rate (f_rep ≥ 10 GHz) ultra-broadband optical frequency combs (OFCs) at 1550 nm and 1310 nm is investigated by seeding two types of highly nonlinear fibers (HNLFs) with 10 GHz picosecond pulses at the pump wavelength of 1550 nm. When pumped near the zero dispersion wavelength (ZDW) in the normal dispersion region of a HNLF, 10 GHz flat-topped OFC with 43 nm bandwidth within 5 dB power variation is generated by self-phase modulation (SPM)-based OFC spectral broadening at 26.5 dBm pump power, and 291 fs pulse trains with 10 GHz repetition rate are obtained at 18 dBm pump power without complicated pulse shaping methods. Furthermore, when pumped in the abnormal dispersion region of a HNLF, OFCs with dispersive waves around 1310 nm are studied using a common HNLF and fluorotellurite fibers, which maintain the good coherence of the pump light at 1550 nm. At the same time, sufficient tunability of the generated dispersive waves is achieved when tuning the pump power or ZDW.