2.0-μm Wavelength Superstructure-Grating-(SSG-) Distributed Bragg Reflector Laser With Tuning Range of Over 50 nm

With the objective of enabling wide tuning characteristics of a semiconductor light source for CO
₂
gas sensing, we demonstrate a 2.0-μm wavelength superstructure grating (SSG-) DBR laser for the first time. SSGs for the 2.0- μm wavelength with seven reflection peak characteristics were designed and introduced to a DBR laser with strained InGaAs multi-quantum-wells (MQWs). The wavelength shift for a single reflection peak due to the carrier-plasma effect was as high as 11 nm, which is sufficient for quasi-continuous tuning characteristics of the SSG-DBR laser. We also found that all seven SSG modes could be individually oscillated by controlling the front and rear SSG-DBR currents. Our evaluation of the lasing characteristics for 40 consecutive channels with 100-GHz spacing show that the lasing wavelength was accurately tuned from 1990.7 nm for the first channel to 2043.4 nm for the 40th channel by using the seven SSG modes. These results demonstrate that the fabricated 2.0-μm wavelength SSG-DBR laser successfully attained a quasi-continuous wavelength tuning of over 50 nm.