Accession Number : ADA307464

Title :   Nanosecond and Subnanosecond Investigations of Intrinsic Optical Limiting Mechanisms in Photorefractive and Semiconducting Materials.

Descriptive Note : Final rept. 31 Mar 89-14 Sep 95,

Corporate Author : IOWA UNIV IOWA CITY CENTER FOR LASER SCIENCE AND ENGINEERING

Personal Author(s) : Smirl, Arthur L. ; Boggess, Thomas F.

PDF Url : ADA307464

Report Date : 15 APR 1996

Pagination or Media Count : 120

Abstract : As a part of the ARPA Eye & Sensor Protection Program, this project has been focused on the exploration of a variety of optical nonlinearities in materials, including semiconductors, organometallic compounds, and photorefractive media, that have potential applications in optical limiting devices. Much of the progress on this project was previously reported in an Interim Final Report (Report # NV-93-C08). This report specifically summarizes progress made on the study of optical nonlinearities in GaP and their applications to optical limiting - research associated with the dissertation work of an AASERT student, funding for whom extended the performance period of this contract from 31 March 1993 to 14 September 1995. These studies have revealed that the dominant nonlinearity responsible for optical limiting at 332 nm in GaP (at fluences below the surface damage threshold of 100 mJ/cm2) is nonlinear refraction arising from band filling effects caused by holes in the valence band. A smaller contribution is found to arise from the free carrier Drude effect. A per carrier index of -3.1(exp-22) cm3 is measured, which is within a factor of three of that predicted by theory. An unusually large two photon absorption coefficient is measured in this material (about -20 cm/GW; roughly an order of magnitude larger than predicted by scaling laws), which may be attributed to transitions to a higher lying conduction band with the fundamental conduction band providing a near resonant intermediate state.

Descriptors :   *NONLINEAR OPTICS, *LIMITATIONS, *EYE SAFETY, *LIMITERS, OPTICAL EQUIPMENT, OPTICAL PROPERTIES, DAMAGE, THRESHOLD EFFECTS, ORGANOMETALLIC COMPOUNDS, SEMICONDUCTORS, VALENCE BANDS, RESONANCE, SCALING FACTOR, PROTECTIVE EQUIPMENT, CONDUCTION BANDS, PHOTOREFRACTIVE MATERIALS.

Subject Categories : Electrooptical and Optoelectronic Devices
      Safety Engineering

Distribution Statement : APPROVED FOR PUBLIC RELEASE