A novel technique of antireflection coatings for infrared semiconductor lasers

Antireflection (AR) coated laser diodes are very much desirable in various external cavity semiconductor laser configurations. Present work describes a simple method of silicon nitride AR coatings on infrared semiconductor lasers. Silicon nitride AR coatings were done on InAlGaAs semiconductor laser diodes emitting at 980nm by reactive sputtering. A residual reflectivity of 10^-2 was achieved which is acceptable for most practical applications. Comparison of experimental observations with the calculations of AR coating thickness and film refractive index shows good qualitative agreement. The AR coated laser diode was tested for its performance by operating it in an external cavity.