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Laser Cavity with Brewster Angle Sidewall

IP.com Disclosure Number: IPCOM000084927D
Original Publication Date: 1976-Jan-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Marinace, JC: AUTHOR

Abstract

In lasers and especially injection lasers, internal reflections in the cavity from the sidewalls are generally undesirable. To reduce these reflections in injection lasers, one method relies on damaging the sidewalls by sawing. This, however, causes current leakage and does not completely suppress the reflections. Another method is to surround the sides of the cavity with an absorbing material, but this contributes to heat generation in the structure.

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Laser Cavity with Brewster Angle Sidewall

In lasers and especially injection lasers, internal reflections in the cavity from the sidewalls are generally undesirable. To reduce these reflections in injection lasers, one method relies on damaging the sidewalls by sawing. This, however, causes current leakage and does not completely suppress the reflections. Another method is to surround the sides of the cavity with an absorbing material, but this contributes to heat generation in the structure.

Sidewalls which are at Brewster angles to the plane of the junction would be nonreflecting to much of the light rays incident upon them. Between GaAs and air, the Brewster angle is 15 degrees 30'.

One easy way to form such a structure in GaAs is to use a GaAs wafer with major surfaces cut so that they are near a (100) orientation, but tilted 15 degrees 30' toward one of the perpendicular (110) planes. A planar junction is formed by diffusion or other conventional means. Individual lasers with four cleaved sides are made in the form of a parallelopiped, with the sidewalls parallel to the long axis. The other two sides are perpendicular to the plane of the cavity and are the regular reflecting mirrors of the laser.

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