Semiconductor Lasers for High-Density Optical Communication Systems

Abstract

Semiconductor lasers have several advantages compared to other types of lasers (a fiber ring laser, a solid-state laser, a gas laser), such as compactness, integrability to other components (a modulator, a power monitor photodiode, a wavelength tuning component). In addition, a monolithic tunable laser can be fabricated in the semiconductor by combining wavelength tuning regions and a phase control region together with an active region. That is why a monolithic integrated semiconductor tunable laser is very attractive not only for a compact light source for large-capacity, optical communication systems but also for economical backup resource. However, there are several technical issues to achieve high-quality semiconductor tunable lasers applicable to high-density optical communication systems due to the severe requirements of narrow spectral linewidth, wide tunability, and high wavelength stability.