InGaN/GaN Distributed Feedback Laser Diodes With Deeply Etched Sidewall Gratings

• Published in: IEEE photonics technology letters Vol. 28; no. 24; pp. 2886 - 2888
• Main Authors: Slight, Thomas J., Odedina, Opeoluwa, Meredith, Wyn, Docherty, Kevin E., Kelly, Anthony E.
• Format: Journal Article
• Language: English
• Published: New York IEEE 15-12-2016; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Coupling coefficients; Diode lasers; Distributed feedback devices; distributed feedback laser diodes; Distributed feedback lasers; Electron beam lithography; Fabrication; Gallium nitride; Gallium nitrides; GaN; Gratings; Indium gallium nitrides; Inductively coupled plasma; InGaN; Laser feedback; lateral gratings; Plasma etching; Semiconductor lasers; sidewall gratings; Waveguides
• ISSN: 1041-1135; 1941-0174
• DOI: 10.1109/LPT.2016.2624500

We report on the design, fabrication, and characterization of InGaN/GaN distributed feedback laser diodes emitting at a single wavelength around 430 nm. Third-order sidewall-etched gratings were used which have the advantage of a simple fabrication route with no need for overgrowth. We carried out waveguide modeling to find the effective modal indices of the grating and calculate the coupling coefficient. The laser ridge and the grating were formed by electron beam lithography followed by inductively coupled plasma etching. The as-cleaved lasers emitted in the pulsed regime with an SMSR of 22 dB and a peak single-mode output power of 40 mW. Slope efficiency was similar for both Fabry-Perot and DFB chips demonstrating that performance is not compromised by the addition of the grating.