CORRUGATION-PITCH MODULATED MQW-DFB LASERS WITH NARROW SPECTRAL LINEWIDTH

Narrow spectral linewidth lasers are developed for optical coherent transmission systems. To obtain a narrow spectral linewidth, a CPM (corrugation-pitch modulated) structure is introduced into 1200-mu-m long MQW-DFB (multi-quantum well distributed feedback) lasers. The CPM structure effectively suppresses the axial spatial hole burning effect and stabilized single-mode spectrum at high output powers. The narrowest spectral linewidth ever of 170 kHz is achieved at an output power of 25 mW. Details of a brand new corrugation fabrication method that makes the CPM structure possible are described.