Abstract

The radiation pattern of multiple quantum well phased array laser diodes is generally complicated. The spatial coherence of such a beam has been measured experimentally using a twin single-mode optical fiber arrangement for sampling the beam at arbitrary points, as well as the traditional Young's double slit method. The aperture separation distances were varied to greater than twice the beamwidth, taken to be the full width at the half-maximum intensity points. Spatial coherence measurements were obtained for emissions parallel and perpendicular to the junction plane. The spatial coherence was found to lie in the 0.2-0.4 range. The visibility also increases slightly with bias current, with zero spatial coherence for below lasing threshold operation.

© 1989 Optical Society of America