Li Xiang, Sia Jia Xu Brian, Wang Jiawei, Qiao Zhongliang, Wang Wanjun, Guo Xin, Wang Hong, Liu Chongyang
Opt Express. 2022 Jan 31;30(3):4117-4124. doi: 10.1364/OE.450071.
Optical frequency combs (OFCs) in the 1.65 µm wavelength band are promising for methane sensing and extended high-capacity optical communications. In this work, a frequency-modulated (FM) OFC is generated from a 1.65 µm single-section quantum well laser. This is characterized by a 1 kHz-wide beatnote signal at ∼19.4 GHz. Typical FM optical spectra are shown and optical linewidth of the OFC narrows through the mutual injection locking process in the comb formation. No distinct pulse train is observed on oscilloscope, which conforms with the FM operation. Furthermore, to add further evidence that four-wave mixing (FWM) is the driving mechanism of the comb formation, FWM frequency conversion characterization is conducted on a semiconductor optical amplifier (SOA) fabricated together with the tested laser. An efficiency of ∼-30 dB confirms the capability of FM mode locking.
波长在1.65微米波段的光学频率梳（OFC）在甲烷传感和扩展大容量光通信方面很有前景。在这项工作中，一个频率调制（FM）的OFC由一个1.65微米的单节量子阱激光器产生。其特征是在约19.4吉赫兹处有一个1千赫宽的拍频信号。展示了典型的FM光谱，并且在梳状结构形成过程中，通过相互注入锁定过程，OFC的光学线宽变窄。在示波器上未观察到明显的脉冲序列，这与FM操作相符。此外，为了进一步证明四波混频（FWM）是梳状结构形成的驱动机制，在与测试激光器一起制造的半导体光放大器（SOA）上进行了FWM频率转换特性测试。约 -30分贝的效率证实了FM锁模的能力。
