Technologies and applications of Al‐free high‐power laser diodes

Abstract

TSUYOSHI OHGOH, TOSHIAKI FUKUNAGA, and TOSHIRO HAYAKAWA Frontier Core-Technology Laboratories, R&D Management Headquarters, Fuji Photo Film Co., Japan SUMMARYWe report high-power technologies in 0.8-µm Al-free InGaAsP/InGaP laser diodes. To realize the high-power operation, the improvement of catastrophic optical mirror damage (COMD) power density level is required. In addition to the use of low surface recombination velocity of Al-free materials, optimization of waveguide thickness in broad waveguide structure with tensile-strained barriers and current blocking structure near facets has led to high COMD power density level. Highly stable operation of Al-free laser diodes with these structures has been obtained over 2500 hours at 2 W from a stripe width of 50 µm. Applications of high-power laser diodes are also described.

Mechanisms and fast kinetics of the catastrophic optical damage (COD) in GaAs‐based diode lasers

“…The same group also reported facet temperature analysis in quantum cascade devices [123,129]. Hayakawa et al [120][121][122] investigated the impact of device design parameters such as emitter stripe width and waveguide thickness on the facet temperature. Piva et al [57,58] quantified the effect of QW intermixing to facet temperatures and found a substantially reduced facet temperature for devices with non-absorbing mirrors.…”

“…The required lateral resolution is achieved with a microscope and lock-in detection schemes result in high detection sensitivities. The required reflectance modulation is typically achieved by temperature modulation of the investigated device via the operation current [28,39,57,58,117,118,[120][121][122]. In contrast to the micro-Raman-approach, one records only two scalar quantities, namely R and ΔR at the particular wavelength (typically via two channels of the look-in amplifier)…”

Precise Facet Temperature Distribution of High- Power Laser Diodes: Unpumped Window Effect

“…Other papers have studied the influence of unpumped windows on laser diode reliability, either by simulation [4] or experimentally [3], [11]. In [11], Ohgog and al studied the effect of a current blocking region on the light output power and on the driving current. In [3], Rinner uses μ-Raman spectroscopy to evaluate the facet and averaged waveguide temperatures.…”

Feasibility study for Al-free 808 nm lasers with asymmetric barriers suppressing waveguide recombination

“…14 Although the quality of facet mirror passivation was greatly improved and AlGaAs-based diode lasers later proved their reliability, Al-free laser heterostructures still remain an alternative solution for high-power diode lasers (see, e.g., Refs. 13,15,and 16).…”