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Coherent GaAs Array Light Source

IP.com Disclosure Number: IPCOM000091019D
Original Publication Date: 1969-Sep-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Gamblin, RL: AUTHOR

Abstract

GaAs diodes, operating in a single spatial coherent mode, can be used as a light source in a holographic store. An array of these GaAs diodes is shown at the left. Each diode has an antireflection coating on its front surface and a reflection coating on its back surface. An external cavity is provided consisting of lenses 1 and 2, an aperture, cylindrical lenses and a mirror. Lasing action is indicated by the paths in the cavity, one of which proceeds from a selected diode and passes through the lenses, aperture, and through a selected one of the cylindrical lenses to a point of incidence on the mirror. From this point of incidence, light is reflected back along a second path through the cavity and finally back to the selected diode.

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Coherent GaAs Array Light Source

GaAs diodes, operating in a single spatial coherent mode, can be used as a light source in a holographic store. An array of these GaAs diodes is shown at the left. Each diode has an antireflection coating on its front surface and a reflection coating on its back surface. An external cavity is provided consisting of lenses 1 and 2, an aperture, cylindrical lenses and a mirror. Lasing action is indicated by the paths in the cavity, one of which proceeds from a selected diode and passes through the lenses, aperture, and through a selected one of the cylindrical lenses to a point of incidence on the mirror. From this point of incidence, light is reflected back along a second path through the cavity and finally back to the selected diode.

The arrangement provides for spatial coherence since, in order to obtain optical feedback, the lasers have to lase in a spatially coherent mode. In order to obtain temporal coherence, only a very narrow band of optical frequencies is permitted by the system. Such is provided by the output mirror which can be arranged of suitable dielectric layers to reflect only in a very narrow band of frequencies.

The total arrangement thus provides for a set of spatially and temporally coherent light sources, any one of which can be individually activated. The advantages of the system lie in the fact that each diode of the array can be made spatially coherent in the absence of a flys-eye lens and also temporally by...