Ultrahigh-repetition frequency pulse generation in DFB lasers by cw light injection for long-haul OTDM fiber transmission

摘要

Abstract: We present a new method for the generation of short optical pulses in DFB-lasers with repetition rates from 10 to greater than 100 GHz. The method does not require any electronic HF-control and is based on cw-light injection into another cw operated DFB-laser. The pulse generation is studied by a transmission line laser model (TLLM) containing spatial hole burning and all relevant effects including spontaneous emission noise of complex coupled multisection DFB-lasers. A special pulse source has been optimized by the TLLM with respect to single-mode output power under cw-operation and yield. Modulation of pulse sequences by an external modulator has been simulated at bit-rates of 40 Gb/s. The effect of pulse broadening on long haul dispersion shifted single mode fiber (DSSF) transmission due to the spectral width is studied. Two by 20 Gb/s OTDM results are compared to 40 Gb/s direct external modulation. !7