Device characteristics and metal-dielectric high reflectivity coating analysis of λ ∼ 1.3 µm InGaAsP/InGaAsP MQW PBH lasers

• Published in: Physica status solidi. A, Applications and materials science Applications and materials science, 2010-01, Vol.207 (1), p.217-223
• Main Authors: Leem, J. W., Yu, J. S.
• Format: Article
• Language: English
• Subjects: 42.55.Px; 42.79.Wc; 78.67.Pt; 81.05.Ea; 85.35.Be; 85.60.-q; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Lasers; Optics; Physics; Semiconductor lasers; laser diodes
• ISSN: 1862-6300; 1862-6319
• DOI: 10.1002/pssa.200925166

The cavity length‐dependent characteristics of compressively strained InGaAsP/InGaAsP multiple quantum well planar buried heterostructure lasers operating at λ ∼ 1.3 µm were investigated under continuous‐wave mode. The uncoated 600 µm long laser exhibits Pmax = 33.6 mW and Ith = 12.9 mA at 25 °C with dλ/dT = 0.35 nm/K and dλ/dPe = 0.044 nm/mW, leading to stable beam characteristics of 19.7° (parallel) × 24.1° (perpendicular). From the inverse slope efficiency versus cavity length plot, the loss parameters of internal differential efficiency (ηi) and internal optical loss (αi) were extracted, i.e., ηi = 78% and αi = 10.6 cm−1. The transparent current density of Jtr = 0.12 kA/cm2 and modal gain of G = 49.5 cm−1 were also estimated from cavity length‐dependent threshold current density measurements. Metal–dielectric Au/Ti/SiO2 layers for high reflectivity (HR) coating were analyzed using theoretical calculations and experimental results. For the HR‐coated 600 µm long laser with Au (150 nm)/Ti (5 nm)/SiO2 (250 nm), Pmax increased up to 61 mW at 25 °C with a reduced Ith of 10.6 mA compared to the uncoated laser, providing an HR of about 94%.