Recent progress on intensity and chirp compensation of EADFB laser realized by SOA integration

摘要

A novel approach is demonstrated for overcoming the trade-off relationship between the power consumption and transmission distance of an electro-absorption modulator integrated with a DFB laser (EADFB laser). We demonstrate that the monolithic integration of a short semiconductor optical amplifier (SOA) with an EADFB laser is effective in overcoming the limitation imposed by the Kramers-Kronig (K-K) relation of the EA modulator, which cannot be overcome with the conventional method of optimizing the MQW structure of the EA modulator. Our approach provides an EADFB laser with two advantages. One is that we can realize a higher optical output power with smaller power consumption than with a conventional EADFB laser by reducing the DFB laser injection current and allocating it to the SOA section. We design the SOA length based on this concept. The other advantage is the chirp compensation of the EA modulator with the SOA. To confirm the validity of this approach, we investigate the SOA length dependence on the basic characteristics. By using an EADFB laser integrated with a 50-μm-long SOA, we achieve a 2 dB increase in the modulated output power compared with a stand-alone EADFB laser with the same power consumption. We realize an extended transmission distance of 5 km at 40 Gbit/s, and a 1.55-μm-wavelength window, which is conventionally achieved for a 2-km SMF transmission with an EADFB laser. These results indicate that this approach is a promising way to realize a high-speed light source with low power consumption for future large capacity optical network systems.