Improvement on Direct Modulation Responses and Stability by Partially Corrugated Gratings Based DFB Lasers With Passive Feedback

DFB lasers with ultrashort cavities or integrated passive waveguide reflectors are frequently proposed to realize directly modulated (DMLs) for carrying ultrahigh data rate signals. The former suffers from poor heatsink and laser cleavage yield, while the single-mode stability of latter scheme is seldom addressed. mode selection device performance a well known be very sensitive facet reflection external optical feedback. partial corrugated gratings feedback (PCG-PFL) here overcome challenging issues aforementioned two schemes. With PCG structure, can maintain high yield (SMY) even high-reflection-coating on rear strong section. This provides robustness in applying reflector reshape modulation response enhance 3-dB bandwidth by using photon-photon resonance (PPR) effect. By designing PCG-PFL have 150-μm long section, 50-μm 30% front-facet reflectivity, it about 86% SMY, reduced resonant peak intensity response, waveform overshoot undershoot transmitting 56-Gbaud/s PAM-4 longer reflector, enhanced achieved PPR