Optimization of the epitaxial structure of low-loss 885nm high-power laser diodes

Abstract

Aiming at the epitaxial structure of the high-power 885nm laser diodes, the factors limiting the further increase of the output power and the power conversion efficiency were investigated. According to the analysis, the epitaxial structure of the laser diodes was optimized, and the influence of the waveguide layer thickness on the carrier absorption loss and the series resistance was theoretically simulated. The results showed that the asymmetric waveguide structure with the thickness ratio of the N-side and the P-side of 6:4 can reduce the carrier absorption loss to the greatest extent. Based on the simulation results, the 885nm laser bars with the optimized epitaxial structure were fabricated and tested under the ambient temperature of 25℃ in a quasi-continuous wave mode of 250μs and 200Hz. The slope efficiency reaches 1.26W/A, while the series resistance is only 1.2mΩ. The power of 277.6W is achieved at 250A injection current and the maximum power conversion efficiency exceeds 64%.