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Second Harmonic Generation with Semiconductor Lasers

IP.com Disclosure Number: IPCOM000052621D
Original Publication Date: 1981-Jun-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Hewig, GH: AUTHOR [+2]

Abstract

A technique for second harmonic generation (SHG) with semiconductor lasers in a waveguide structure is described which comprises the use of high-index amorphous films deposited on substrates with high nonlinearity for improving the second harmonic generation.

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Second Harmonic Generation with Semiconductor Lasers

A technique for second harmonic generation (SHG) with semiconductor lasers in a waveguide structure is described which comprises the use of high- index amorphous films deposited on substrates with high nonlinearity for improving the second harmonic generation.

The nonlinear process of SHG requires a large power density at the fundamental frequency and the confinement of that power density over long interaction lengths. When the incident power is small, as from a semiconductor laser, the only way to achieve this is by propagating the light as a guided wave in an optical waveguide. For SHG by guided waves, either the nonlinearity of the guide film, or the substrate, or the cover can be used. Up to now, most experiments have used the guide film as the nonlinear medium, which, of course, requires the film to be single-crystal. Such films are very difficult to deposit, and usually show very high propagation losses, normally several tens of dbs/cm. The small interaction length results in poor SHG efficiency.

The structure described here circumvents this problem by using an amorphous film for propagating the light and utilizing the nonlinearity of a crystalline substrate for the SHG. Amorphous films, such as lithium niobate thin films can be extremely loss-free; for example, with a GaAs laser propagation, lengths of Approximately 3 cm (corresponding to a loss Approximately 2 db/cm) can be obtained in a Approximately 1...