Abstract

The need for small, fast, high quality lenslets has become apparent over the last few years, with the development of diode laser sources, and in particular diode laser arrays. Since diode lasers typically have a beam divergence of a few tens of degrees, collimating the output beams generally leads to greatly improved far-field patterns. The preferred substrate for lenslet fabrication has been fused silica, on which both diffractive⁽¹⁾ and refractive⁽²⁾ lenslets have been investigated with good results. However, the small index of refraction of quartz (n=1.5) can present problems with high aspect ratio features, such as the outer rings of Fresnel zone plates. In this paper we describe the fabrication and performance of ~f/1 microlenses fabricated on semiconductors, rather than quartz, wafers, where n~3. Binary Fresnel lenslets were fabricated in InP by wet etching, while InP and GaP were used to fabricate refractive lenslets by wet etching followed by mass transport.

© 1990 Optical Society of America