High-frequency mode-beating in distributed feedback laser with a semiconductor optical amplifier

A monolithic semiconductor laser, which can generate high frequency mode-beating over 100GHz, is reported. This laser employs a semiconductor optical amplifier (SOA) as the integrated feedback cavity of a complex-coupled distributed feedback laser (DFB). Stable dual-mode emission, with low strength difference is demonstrated. Mode-beating frequency of this laser can be tuned from 87.41 to 103.64 GHz, when the currents injected into each laser section are adjusted. In all frequency range, the strength difference of two main modes is smaller than 10 dB and the strength of the other side mode is 20 dB lower than the two main modes.