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ELECTRICAL SUPPRESSION OF REFLECTED LIGHT INDUCED NOICE IN THE OUTPUT OF SEMI-CONDUCTOR LASERS

IP.com Disclosure Number: IPCOM000025606D
Original Publication Date: 1986-Aug-31
Included in the Prior Art Database: 2004-Apr-04
Document File: 2 page(s) / 125K

Publishing Venue

Xerox Disclosure Journal

Abstract

It is well known that light reflected back into the cavity of a semiconductor laser or laser diode causes random fluctuations in output intensity of the laser which is undesirable "noise". This reflected light induced noise degrades system performance in systems such as those, for example, employing a laser diode for reading information from an optical disk.

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KEROX DISCLOSURE JOURNAL

ELECTRICAL SUPPRESSION OF Proposed Classification REFLECTED LIGHT INDUCED
NOICE
IN THE OUTPUT OF SEMI-
CONDUCTOR LASERS
Thomas L. Paoli
Robert D. Burnham
William Streifer

U S. C1.372/38 Int. C1. HOls 3/00

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INPUT ~

CURRENT

FEEDBACK

APPLIED HIGH CURRENT CURRENT

LASER

DIODE

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ft

-

It is well known that light reflected back into the cavity of a semiconductor laser or laser diode causes random fluctuations in output intensity of the laser which is undesirable "noise". This reflected light induced noise degrades system performance in systems such as those, for example, employing a laser diode for reading information from an optical disk.

One solution to eliminating this undesirable noise is the insertion of an optical isolator comprising a polarizer and a quarter-wave plate between the laser and an external reflecting surface. However, many optical disk systems depend on a linearly polarized beam and, because of this, optical isolation 1s

not possible since the output of' a quarter-wave plate is generally elliptically polarized. Also, this approach is cumbersome due to the requirement for additional, external optical components. Thus, alternate methods of suppressing reflection induced noise in semiconductor lasers is of interest.

One alternate method is described by M. Nakamura, et al. in the paper MJ2 presented at the Third International Conference on Integrated Optics & Optical Fiber Communication, April 27-29, 1981, San Francisco, California, entitled "Elimination of Laser Noise and Distortion Induced by Reflected

Volume 11 Number 4 July/August 1986 193

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ELECTRICAL SUPPRESSION OF REFLECTED LIGHT INDUCED NOICE IN THE
OUTPUT OF
SEMICONDUCTOR LASERS (Cont'd)

Waves." The method employs a photodiode to detect the fluctuations in the laser's output in a negative feedback loop. This approach requires either sampling the output beam or detecting the output from the rear facet mir...