Characterizing the Coherence of Broadband Sources using Optical Phase Space Contours.

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. © 1999 Society of Photo-Optical Instrumentation Engineers.

Generation of subpicosecond high-power optical pulses from a hybrid mode-locked semiconductor laser.

Ultrashort optical pulses 0.46 psec in duration with over 70 W of peak power are generated from an all-semiconductor laser-diode system. These results represent to our knowledge both the shortest and most-intense optical pulses generated from an all-semiconductor laser system.

Broadband acoustooptic deflectors: new results.

A new broadband acoustooptic (AO) Bragg deflector using acoustic beam steering to track the Bragg angle is described. It features, instead of the conventional stepped array acoustic grating to produce the steering sound column, a flat transducer grating made from a single piezoelectric platelet bonded to the AO medium, with the spatially periodic phase variations created by interdigitating the electrode configuration. The advantage over the conventional stepped array, for deflectors operating at frequencies above 100 MHz, is the ease of fabrication of the device, an advantage that far outweighs its somewhat reduced acoustic power available for light diffraction. An analysis is presented to show that the achievable half-power bandwidth from beam steering deflectors under optimum design considerations is over four times the bandwidth of fixed beam deflectors having the same transducer dimensions. Experimental results on lead molybdate deflectors confirm the predicted fourfold improvement.