Enhanced power conversion efficiency in high power single spatial mode ridge waveguide diode lasers using extreme triple asymmetric epitaxial structure

Single-spatial-mode lasers with high efficiency and watt-level output in the 97x-nm wavelength range are in strong demand for a variety of applications. In this work, we explore ridge waveguide (RW) lasers based on an Extreme Triple Asymmetric (ETAS) epitaxial structure. Through optimized epitaxial design, the conversion efficiency of our ETAS-based ridge lasers is improved by over 12% at high powers compared to our prior designs using an Extreme Double Asymmetric (EDAS) structure. A 7-µm ridge-width ETAS-based laser with an antireflection (AR) coating of R_f = 2% and a high reflection (HR) coating of R_r = 95% achieves single-spatial-mode operation, delivering a peak efficiency of 61.2% at 1 W output and sustaining 60.1% efficiency at 1.41 W output under 1.5 A drive current. Reducing AR coating reflectivity (R_f = 0.5%) enhances beam quality, achieving near-diffraction-limited single-mode emission with M² 1/e values maintained below 1.15 up to a drive current of 1.45 A. These results highlight the potential of ETAS-based lasers for high-performance applications requiring high-power high-efficiency single-spatial-mode lasing emissions.