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Asymmetrical Grating Coupled Laser Configutations

IP.com Disclosure Number: IPCOM000084934D
Original Publication Date: 1976-Jan-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 50K

Publishing Venue

IBM

Related People

Zory, PS: AUTHOR

Abstract

In grating coupled (GC) waveguide laser configurations designed so that the output beam leaves the device normal to the waveguide plane, [1] interference effects can occur which limit the amount of output power. In essence what can happen, is that the two leaky waves (derived from the oppositely directed laser beams in the waveguide) which contribute to the output beam can destructively interfere. It can be assumed that this is likely to happen since lasers will always operate so as to minimize their losses. In this case, the phases of the oppositely directed laser beams will adjust so as to minimize the leaky wave losses.

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Asymmetrical Grating Coupled Laser Configutations

In grating coupled (GC) waveguide laser configurations designed so that the output beam leaves the device normal to the waveguide plane, [1] interference effects can occur which limit the amount of output power. In essence what can happen, is that the two leaky waves (derived from the oppositely directed laser beams in the waveguide) which contribute to the output beam can destructively interfere. It can be assumed that this is likely to happen since lasers will always operate so as to minimize their losses. In this case, the phases of the oppositely directed laser beams will adjust so as to minimize the leaky wave losses.

One way to get around this problem is to design the device so that one of the leaky waves which contribute to the output beam normal to the waveguide plane is very weak. In coming up with a design to do this, it is necessary to know that the intensity of a leaky wave derived from a unidirectional guided mode depends basically on the power in the mode and the output coupling coefficient for that direction. Consequently, in order to obtain the desired asymmetry in the leaky waves one of the following configurations must be worked into the design: (1) Symmetrical Grating - Asymmetrical guided mode power. (2) Asymmetrical Grating - Symmetrical guided mode power. (3) Asymmetrical Grating - Asymmetrical Guided mode power. Examples of classifications (1) and (2) are sketched in Figs. 1 and 2, respectiv...