Characterizing the Coherence of Broadband Sources using Optical Phase Space Contours

Abstract

Advances in optical coherence tomography (OCT) rely on the availability of broadband light that is spatially coherent. We present a technique to characterize coherence properties of broadband light using optical phase-space contours in transverse momentum and position. We demonstrate that these contour plots can be directly measured by a simple heterodyne imaging scheme possessing high dynamic range (130 dB) and 0.1 fW sensitivity (for mW input beams). These phase space distributions are shown to yield quantitative information on the longitudinal and transverse coherence and the wavefront curvature of the light beam. We apply this technique to characterize the light emitted by a novel high-power extended-bandwidth superluminescent diode (SLD) recently developed at the David Sarnoff Research Center. Its performance is compared to that of standard commercially available SLDs. (c) 1999 Society of Photo-Optical Instrumentation Engineers.