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Monolithic Acousto Optic Light Deflector and Modulator

IP.com Disclosure Number: IPCOM000078899D
Original Publication Date: 1973-Apr-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Lean, EG: AUTHOR

Abstract

This description relates to the use of a steerable acoustic plate wave or a steerable acoustic surface wave, excited by an interdigital transducer array on a thin plate or a substrate, to deflect a laser beam in the thin plate or an optical guided wave. To understand the advantages of this deflection scheme, the basic operation principle and difficulties of bulk acoustic deflector have to be reviewed.

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Monolithic Acousto Optic Light Deflector and Modulator

This description relates to the use of a steerable acoustic plate wave or a steerable acoustic surface wave, excited by an interdigital transducer array on a thin plate or a substrate, to deflect a laser beam in the thin plate or an optical guided wave. To understand the advantages of this deflection scheme, the basic operation principle and difficulties of bulk acoustic deflector have to be reviewed.

The normal bulk acoustic light deflector is based on Bragg diffraction of light by acoustic waves. The efficiency of this acousto-optic deflector is given by:

(Image Omitted)

Normally the Bragg cell is made of isotropic medium. The bandwidth and so the resolution is inversely proportional to the bandwidth W. There exists a conflict between the requirement on W for low- input driving acoustic power and large bandwidth.

One solution for this conflicting requirement on W is to make a steerable acoustic column by fabricating a transducer array, as shown in Fig. 1. The adjacent transducers are separated in steps by a multiple of half-acoustic wavelengths at center frequency. For an acoustic frequency higher than 100 MHz, the fabrication of the step transducers become a problem and costly.

Described is a scheme of light deflection using guided acoustic waves, as shown in Fig. 2. The medium is the thin crystal plate with a thickness d. An interdigital transducer array is used to excite a steerable acoustic plate mode. The in...