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Browse Prior Art Database

Thin Film Light Modulator

IP.com Disclosure Number: IPCOM000083789D
Original Publication Date: 1975-Jul-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Fink, H: AUTHOR [+2]

Abstract

Prior art thin film light modulators have been proposed, in which the optical properties of a thin film waveguide have been modified by changing the carrier concentration in the waveguide material, for example, GaAs. This description deals with modifying the optical properties of a thin film waveguide by changing the boundary conditions.

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Thin Film Light Modulator

Prior art thin film light modulators have been proposed, in which the optical properties of a thin film waveguide have been modified by changing the carrier concentration in the waveguide material, for example, GaAs. This description deals with modifying the optical properties of a thin film waveguide by changing the boundary conditions.

As shown, an optical waveguide film b, such as zinc oxide or strontium titinate is positioned on a substrate a. On top of the waveguide b film is a semiconductor film c. The substrate a and the semiconductor c should have a lower index of refraction than the optical waveguide film b. The semiconductor film is silicon, germanium or gallium arsenide, which is heavily doped with a carrier concentration of about 10/16/ to 10/17/.

An alternative approach to a semiconductor film c having a lower refracted index than waveguide film b, is to have it be a thin and small semiconductor film. The laser light guide path d passes under junction f of the semiconductor material c. Two electrodes e are positioned on the semiconductor c. The positions of the electrodes e should be as close as feasible to junction f.

The carrier concentration of the semiconductor material c is varied and this, in turn, modulates the light being transmitted by rejection in the optical waveguide film b. The carrier concentration may be varied in a number of different ways. One approach to draw alternately a current in the forward bias direct...