Narrow Linewidth Distributed Bragg Reflectors Based on InGaN/GaN Laser

Abstract

A variety of emerging technologies, such as visible light communication systems, require narrow linewidths and easy-to-integrate light sources. Such a requirement could be potentially fulfilled with the distributed Bragg reflector (DBR) lasers, which are also promising for the monolithical integration with other optical components. The InGaN/GaN-based surface etched DBR is designed and optimized using the finite-difference-time-domain (FDTD) method to obtain very narrow-band reflectors that can serve as a wavelength filter. The results reveal that the ultimate reflectivity depends on the grating period and duty ratio of the DBR. Based on the design, the DBR lasers with various duty ratios are fabricated, specifically, the 19th, 13th and 3rd order DBR grating with duty ratio set as 50%/75%/95%. The minimum linewidth could be achieved at 0.45 nm from the 19th order grating with a 75% duty ratio. For comparison, the Fabry–Pérot (F–P) based on the same indium gallium nitride/gallium nitride (InGaN/GaN) epitaxial wafer are fabricated. The full width at half maximum (FWHM) of the DBR laser shrank by 65% compared to that of the conventional F–P laser, which might be helpful in the application of the visible light communication system.

Group-III-nitride and halide-perovskite semiconductor gain media for amplified spontaneous emission and lasing applications

“…This approach is important for lasers that are integrated into monolithic photonic circuits where it is difficult to implement facet cleaving and dielectric mirror coatings. Available reports discuss discrete laser-DBR integration (λ range of 400-407 nm) [214,[259][260][261][262][263][264], but further investigation is required at the level of photonic circuit integration. Similarly, integration of laser diodes with a special type of diffraction grating enables vertical emission from in-plane lasers at λ of 407 nm (see figure 16(b)) [213,265].…”

Lateral characteristics improvements of DBR laser diode with tapered Bragg grating

“…[10] In 2019, Xie et al designed a DBR laser with the nineteenth order grating to achieve 0.45-nm linewidth. [11] The full width at half maximum (FWHM) linewidth of the DBR laser was narrowed by 65% in comparison with that of the conventional laser. In 2019, Chen et al designed a DBR laser with output power of 9.9 mW and ultra-narrow linewidth of 70 kHz.…”

Photonic Stopband Filters Based on Graphene-Pair Arrays

“…Bragg gratings, which are formed by modulating the refractive indices of materials or spatial structures of systems periodically, are extensively utilized for optical filters [1,2], fiber lasers [3] and optical reflectors [4,5]. Two identical Bragg gratings are assigned on both sides of a bulk dielectric to form the distributed feedback Bragg gratings, which are usually applied to realize wavelength selectors [6].…”