Browse Prior Art Database

Light Pipe with Gain

IP.com Disclosure Number: IPCOM000094853D
Original Publication Date: 1965-Jun-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Stern, F: AUTHOR

Abstract

Light is transmitted by the light pipe from source to sin with amplification of intensity. The light pipe is suitable for interconnecting optical and optical-electronic devices in integrated circuitry. Basically, it is a three-layer semiconductor structure, of which the host material can conveniently be GaAs.

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Light Pipe with Gain

Light is transmitted by the light pipe from source to sin with amplification of intensity. The light pipe is suitable for interconnecting optical and optical- electronic devices in integrated circuitry. Basically, it is a three-layer semiconductor structure, of which the host material can conveniently be GaAs.

Light pipe 10 in the left-hand drawing consists of moderately to heavily doped N-type substrate 12, lightly doped N-type region 14 prepared by diffusion, heavily doped P-type region 16 prepared by diffusion or evaporation, and vapor deposited metallic contact 18. As irregularities in light pipe 10 increase losses and cause instabilities at high gain, regions 12, 14 and 16 have smooth surfaces. Because of the high index of refraction of GaAs, light is transmitted around gradual bends in the light pipe.

There are no sharp corners in light pipe 10 as they introduce losses and cause instabilities. For a large enough forward current in the PN junction, a light signal introduced at the input end of light pipe 10 is amplified along the path to the output end. By terminating the ends of the light pipe with coatings having low reflectivity, the current through the junction can be increased without causing laser action.

In the right-hand drawing, light pipe 10 feeds two output pipes 20 and 22 within which the respective desired level of gain is set by independently controlling the junction current.

The dimensions and doping levels of the various parts of light pipe 10 are not critical. Lightly doped N-type region 1...