Abstract

As a result of different sizes of the waveguide in the directions parallel and perpendicular to the junction, semiconductor edge-emitting lasers emit in rather elliptical beam profile with the divergence angles of about 10° × 40°. This makes the coupling of the laser beam into a round optical fiber difficult and inefficient. Hence, it is desirable to reduce the beam ellipticity by correcting elements. Several methods have been presented for correcting the elliptical profiles and improving the coupling efficiency.^1,2 However, some of these special lenses are difficult to fabricate or not easy to align. Recently, a novel free-space micro-optical bench (FS-MOB) technology, using surface-micromachining techniques, has been demonstrated to realize micro-optical components, micropositioners, and microactuators monolithically using batch fabrication techniques.³ Previously, we have successfully used the micro-Fresnel lenses to collimate the divergent light from the semiconductor laser.³ In this paper we will demonstrate how the collimated beam can be further corrected to a round profile by using three cylindrical micro-Fresnel lenses.

© 1997 Optical Society of America