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Browse Prior Art Database

Optical Transducer

IP.com Disclosure Number: IPCOM000091213D
Original Publication Date: 1969-Nov-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Lynch, RJ: AUTHOR [+2]

Abstract

Semiconductor diode 10 emits light at a predetermined spectral frequency when forward biased above the threshold voltage level Vt. Diode 10 senses light at the same frequency when biased below level Vt.

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Optical Transducer

Semiconductor diode 10 emits light at a predetermined spectral frequency when forward biased above the threshold voltage level Vt. Diode 10 senses light at the same frequency when biased below level Vt.

Diode 10 is a ternary compound of Group III and V elements such as GaAlAs. PN junction 11 is formed between opaque P layer 10a and transparent N layer 10b. Double-pole, double-throw switch 12 is connected to a power supply, e.g., battery 13 and adjustable resistor 14. With arms a of switch 12 closed with switch contacts I, diode 10 is reverse biased Rev. With arms a of switch 10 closed with the switch contacts II, diode 10 is forward biased Fwd.

When biased Fwd above level Vt, diode 10 operates in Emit region A of its characteristic curve and emits light at a given spectral frequency. When diode 10 is biased in the Sense region of curve A, i.e., between level Vt and the Reverse Breakdown region, it senses or detects light at substantially the same spectral frequency.

For example, a GaAlAs diode, when biased in the Emit region, emits visible light in the red spectrum at substantially 6750 angstroms. When biased in the Sense region, the diode senses visible red light at substantially the same spectrum, curves B and C. The bandwidth BW associated with the diode is less than 400 angstroms.

GaAlSb, GaTlAs, GaAlP, and GaInP are other examples of ternary Group III and V compounds which are useful for fabricating optical transducers A GaAlSb PN junction...