Ultra-Fast Wavelength Switching DS-DBR Laser with Enhanced Coherence Enabled by Optical Injection Locking

The rapid increase of traffic in intra-data center (DC) networks has motivated nanosecond-scale wavelength switching laser, such as fast wavelength switchable laser [1], [2] and semiconductor optical amplifier (SOA) switched based wavelength arrays [3], to overcome DC networks' scalability bottlenecks in radix and bandwidth [2], [3]. Besides switching time, the demand on high-capacity triggers research into optically switched coherent communications that require light sources to be simultaneously low linewidth and fast switchable. These two requirements, however, are inherently contradictory as narrow linewidth requires a long photon lifetime (thus low switching speed), while fast switching requires a short photon lifetime and high modulation BW. In this work, we investigate linewidth and switching speed behaviour of a fast switchable laser under optical injection locking (OIL) technique [4]. Although OIL for linewidth improvement has been investigated in many previous works, it has not been demonstrated for fast switching lasers. Our contribution here focuses on experimental study of the dynamic behaviour of fast switching laser under OIL, specifically the frequency variation and phase noise during switching and stable operation periods, as well as the impact of OIL power.