Browse Prior Art Database

Electrical Positioning of Lenses on Semiconductor Lasers

IP.com Disclosure Number: IPCOM000086812D
Original Publication Date: 1976-Oct-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 21K

Publishing Venue

IBM

Related People

Marinace, JC: AUTHOR

Abstract

Because of the very small dimensions of the emitting area of a semiconductor junction laser, diffraction causes considerable divergence of the emitted light beam. The use of spherical or cylindrical lenses has been proposed to collimate the light. However, these lenses must be very precisely positioned, and with the small dimensions involved, this becomes a difficult problem.

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Electrical Positioning of Lenses on Semiconductor Lasers

Because of the very small dimensions of the emitting area of a semiconductor junction laser, diffraction causes considerable divergence of the emitted light beam. The use of spherical or cylindrical lenses has been proposed to collimate the light. However, these lenses must be very precisely positioned, and with the small dimensions involved, this becomes a difficult problem.

The method proposes that a reverse-biased junction laser be immersed in an emulsion of a lacquer, varnish or similar material. The finely divided droplets of lacquer will collect at the junction (the emitting region) and coalesce into a larger droplet. If the finely divided particles have an electrical charge, they will tend to collect on one side of the junction or the other, depending upon the sign of the charge. If they are uncharged and have a dielectric constant greater than that of the medium, it is expected that they will deposit directly at the junction.

The laser is removed from the emulsion and dusted with a powder of small spheres having the desired optical properties and size. The first sphere to strike the liquid lacquer will adhere, and when the lacquer cures, the sphere will de held precisely on the emitting region as shown in the figure.

A still simpler method would be possible if a lacquer or or some similar material could be found which does not "wet" the laser mirror. Then the coalesced droplet itself would be the sp...