Optical and RIN Spectrum Improvements in Necked Waveguide High-Power DFB Laser Diode

A novel high power distributed feedback (DFB) laser is proposed which uses a partially narrow waveguide and corrugation pitch modulated (CPM) phase shift grating. Compared with conventional DFB lasers with constant waveguide width, these necked DFB lasers have greater improvements in terms of optical and relative intensity noise (RIN) spectrum. They are less sensitive to external optical feedback (EOF) and increase the range of the injection current for single longitudinal mode (SLM) operation. It can not only suppress the multimode lasing state under high injection current and EOF intensity, but also realize the SLM operation with RIN < −135 dB under a EOF intensity of less than −15 dB in the current range of 150 mA ~ 350 mA. Therefore, the range of injection current for SLM operation was increased for continuous wave (CW) light sources in silicon-based hybrid photonic integration applications.