Effect of antireflection facet coatings on the characteristics of a high-power red laser diode

We investigated the effect of antireflection (AR) coatings on the performance of high-power red laser diodes (LDs). The AR coating at the front facet and the high reflection (HR) coating at the rear facet were deposited on cleaved facets. As an AR coating, SiO₂ or Si₃N₄ single layers with different thicknesses were employed. When the reflectivity of the AR coating was 25%, the best LD performance was obtained. The fitting to the threshold current density vs. effective optical length plot produced a transparent current density of 310 A/cm². Under continuous wave (cw) operation at 15 °C, the operating current was 1.41 A, and the operating voltage was 2.33 V with an optical output of 280 mW. At an operating temperature of 0 °C, we observed the maximum output power of about 390 mW.