Fabrication of Widely Tunable SGDBR Laser Using Butt-Joint Technique

摘要

Widely tunable laser diodes are key components for agile optical networks and optical sensing systems. In this paper, a monolithic widely tunable sampled grating distributed Bragg reflector (SGDBR) laser diode was fabricated using LP-MOCVD. Butt-joint technique was adopted to realize lateral integration of MQW active area and passive waveguide. The etching process and MOCVD regrowth were well optimized to obtain ultra low loss butt coupling and improve the reproducibility. The coupling loss of butt-joint waveguide is as low as 7cm~(-1). The fabricated SGDBR laser used a typical ridge waveguide (RWG) structure due to the advantage of the simple fabrication processing. It was consisted of four sections, two "sampled grating" passive reflectors (front mirror and rear mirror), MQW gain section, and phase section. This SGDBR laser diode had 26mA threshold current and 9mW maximum output power at 100-mA continuous-wave operation. Through control of the injection current of front mirror and rear mirror, the spectra with the tuning range of more than 41 nm was obtained. And the wavelength can be precise aligned at ITU wavelength by well adjustment of the phase section injection current. The side mode suppression ratio in the whole tuning range was more than 30dB.