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Producing Modulated Infrared Radiation

IP.com Disclosure Number: IPCOM000097628D
Original Publication Date: 1961-Mar-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Winogradoff, NN: AUTHOR

Abstract

Methods of producing modulated infrared radiation are based on (1) modulated injection across a p-n junction, leading to a controlled emission of recombination radiation, (2) modulating the absorption coefficient of some material by varying the free carrier concentration and (3) by rotating the plane of polarization of a polarized beam of infrared radiation by a magnetic effect (Faraday Rotation), or by an electric field (Kerr effect). All these methods generally require considerable power (of the order of 10/2/ amps/cm/2/) and, with the exception of (1) above, produce a degree of modulation of only about 10 percent.

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Producing Modulated Infrared Radiation

Methods of producing modulated infrared radiation are based on (1) modulated injection across a p-n junction, leading to a controlled emission of recombination radiation, (2) modulating the absorption coefficient of some material by varying the free carrier concentration and (3) by rotating the plane of polarization of a polarized beam of infrared radiation by a magnetic effect (Faraday Rotation), or by an electric field (Kerr effect). All these methods generally require considerable power (of the order of 10/2/ amps/cm/2/) and, with the exception of (1) above, produce a degree of modulation of only about 10 percent.

This technique relates to the modulation of the recombination radiation from optically injected carriers by varying the surface recombination velocity of a semiconductor. This technique yields a very high degree of modulation with low power signals (on the order of 10/-3/watts).

A device for the production of modulated recombination radiation in germanium, having a wave length of about 1. 68, is shown schematically. For maximum output the germanium used for electrode 1 should have the maximum possible carrier lifetime. The application of an A.C. signal of approximately 1. 0 volt produces electrolysis of the acid, thus depositing alternately oxidizing and reducing ions on the germanium surface during successive half cycles of the impressed signal. These ions modify the surface recombination velocity of the german...