Browse Prior Art Database

SINGLE MODE INDEX GUIDED DISTRIBUTED FEEDBACK LASER

IP.com Disclosure Number: IPCOM000026377D
Original Publication Date: 1991-Aug-31
Included in the Prior Art Database: 2004-Apr-05
Document File: 2 page(s) / 108K

Publishing Venue

Xerox Disclosure Journal

Abstract

The distributed feedback (DFB) laser has long been recognized as a promising source for communications needs, integrated optoelectronics, and other applications that require either: 1) a stable single-frequency source or 2) planar integration. Unfortunately, for fundamental reasons, the typical DFB laser tends to operate at two wavelengths, the average of which is the center wavelength of the internal feedback. See, e.g., H. Kogelnick and C. V. Shank, "Coupled-Wave Theory of Distributed Feedback Lasers," Journal of Applied Physics, vol. 43, p. 2327 (1972). One solution to this fundamental problem is to fabricate two internal feedback gratings of n/2 relative phase within the same laser. However, the technique of fabricating two phased internal gratings is difficult and laborious. A technique is described to more simply provide single frequency operation from a DFB laser having only one internal grating.

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XEROX DISCLOSURE JOURNAL

SINGLE MODE INDEX GUIDED DISTRIBUTED FEEDBACK LASER John Epler

Proposed Classification
U.S. C1.372/096 Int. C1. HOls 3/08

I yL-1-L I +

I

G

A

Rear Facet

Waveguide

- - -r - - - - -

+I

Front Facet

B

I

index of Refraction n

I I

Fig.

XEROX DISCLOSURE JOURNAL - Vol. 16, No. 4 July/August 1991 265

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SINGLE MODE INDEX GUIDED DISTRIBUTED FEEDBACK LASER(Cont'd)

The distributed feedback (DFB) laser has long been recognized as a promising source for communications needs, integrated optoelectronics, and other applications that require either: 1) a stable single-frequency source or 2) planar integration. Unfortunately, for fundamental reasons, the typical DFB laser tends to operate at two wavelengths, the average of which is the center wavelength of the internal feedback. See, e.g., H. Kogelnick and C. V. Shank, "Coupled-Wave Theory of Distributed Feedback Lasers," Journal of Applied Physics, vol. 43, p. 2327 (1972). One solution to this fundamental problem is to fabricate two internal feedback gratings of n/2 relative phase within the same laser. However, the technique of fabricating two phased internal gratings is difficult and laborious. A technique is described to more simply provide single frequency operation from a DFB laser having only one internal grating.

The center wavelength, ho (measured externally to the device), of an internal grating can be expressed as: ho = 2mA/ncos6, wh...