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Grating Coupling Of Light Generated by Forced Nonlinear Optical Processes

IP.com Disclosure Number: IPCOM000052091D
Original Publication Date: 1981-Apr-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Comerford, LD: AUTHOR [+2]

Abstract

A grating may be used to extract second harmonic light from a nonlinear crystal even when the crystal is lossy at the second harmonic frequency.

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Grating Coupling Of Light Generated by Forced Nonlinear Optical Processes

A grating may be used to extract second harmonic light from a nonlinear crystal even when the crystal is lossy at the second harmonic frequency.

The nonlinear susceptibility of a medium can be very large when the generated light frequency is near to or within an absorption region of the medium. Nonlinear generation of light can thus be very efficient at such frequencies. However, this light is ordinarily not available because of the strong absorption of the medium. This phenomenon has limited the wavelengths at which a given material may be used for generation of light by nonlinear processes to those frequencies at which there is no strong absorption. The described structure overcomes this limitation.

Light produced at frequency w by a nonlinear process can be described as being composed of two parts, a free wave propagating with the (possibly complex) wave vector appropriate to w, and a forced wave propagating with a wave vector equal to the sum of the wave vectors of the fundamental beams. Normal phase matching in a lossless material occurs when these two waves combine constructively. When the material is strongly absorbing at w, the amplitude of the light at w does not grow with distance, but has a constant value at all points in the material. Heretofore, only the light at w generated very close to the exit surface of an absorbing nonlinear material could be observed.

Under the condition...