Tunable acoustic wave propagation device

• US 3,911,381 A
• Filed: 09/06/1974
• Issued: 10/07/1975
• Est. Priority Date: 09/06/1974
• Status: Expired due to Term

• Current Assignee: Reynold S. Kagiwada, Robert E. Brooks
• Original Assignee: Reynold S. Kagiwada, Robert E. Brooks
• Inventors: Brooks, Robert E., Kagiwada, Reynold S.
• Primary Examiner(s): Lawrence, James W.
• Assistant Examiner(s): Nussbaum, Marvin
• Application Number:
  US05/503,900
• Time in Patent Office: 396 Days
• Field of Search: 333/3R,72 310/8,8.1,8.2,9.7,9.8
• US Class Current: 333/195
• CPC Class Codes: G10K 11/36 Devices for manipulating acoustic surface waves electro-acoustic amplifiers H03F13/00; networks comprising electro-acoustic elements H03H9/00
• CPC Class Codes: H03H 9/02795 Multi-strip couplers as track changers
• CPC Class Codes: H03H 9/02968 with optical devices mounting in enclosures H03H9/12
• CPC Class Codes: H03H 9/25 Constructional features of resonators using surface acoustic waves devices for manipulating acoustic surface waves in general G10K11/36
• CPC Class Codes: H03H 9/72 Networks using surface acoustic waves

Abstract

A tunable acoustic wave proparation device such as a wave coupler or filter. A wave coupler, for example, conventionally includes a pair of acoustic transducers coupled to each other by a multistrip coupler consisting of parallel, evenly spaced metal strips to influence the propagation of an acoustic wave. These metal strips are replaced by light stripes generated by interferometric means. For example, two light beams may be generated which are projected at an angle upon a photoconductive layer upon which the conductive strips are generated. By changing either the angle of the two beams or the frequency of the light the spacing between adjacent light stripes can be varied. Their intensity can be varied by a mask which also influences the properties of the coupler.

Claims

1. In a tunable acoustic wave propagation device:

a. a layer of piezoelectric material;

b. a layer of photoconductive material disposed on said piezoelectric layer;

c. a substantially monochromatic light source for generating a first light beam;

d. means for splitting said first light beam into a second and third light beam and for projecting them at a predetermined angle onto said photoconductive layer to generate thereon a series of spaced stripes to render said photoconductive layer conducting where a stripe is projected; and

e. means for varying the angle between said second and third light beams, thereby to vary the spacing of said stripes.

2. In a device as claimed in claim 1 wherein a mask is interposed into the path of said second and third light beams for limiting the area of said photoconductive layer on which said stripes of light are projected and thereby the number of stripes.

3. In a device as defined in claim 1 wherein a mask is interposed between said second and third light beams and said photoconductive layer for controlling the intensity of said light stripes.

4. A tunable acoustic wave coupler comprising:

a. a layer of piezoelectric material;

b. a layer of photoconductive material disposed on said piezoelectric layer;

c. a pair of interdigital acoustic transducers provided on said photoconductive layer and spaced from each other;

d. a source of substantially monochromatic light for generating a first light beam;

e. means for splitting said first light beam into a second and third light beam and for causing said second and third light beams to intersect at said photoconductive layer at a predetermined angle to each other and between said transducers; and

f. means for varying at will the angle between said second and third light beams, thereby to vary the spacing between the light stripes projected on said photoconductive material.

5. A coupler as defined in claim 4 wherein additional interdigital acoustic transducers are disposed on said photoconductive layer and in cooperative relationship with said light stripes.

6. A coupler as defined in claim 4 wherein a mask is interposed between said photoconductive material and said second and third light beams for limiting the area of said light stripes and thereby their number.

7. A coupler as defined in claim 4 wherein a mask is interposed between said photoconductive layer and said second and third light beams for controlling the intensity of said light stripes.

8. In a tunable acoustic wave propagation device:

a. a piezoelectric layer;

b. a photoconductive layer disposed on said piezoelectric layer;

c. a laser for generating a first light beam;

d. means for splitting said first light beam into a second and a third light beam and for projecting them onto said photoconductive layer at a predetermined, fixed angle; and

e. means for varying the frequency of the light beam developed by said laser, thereby to vary the distance between adjacent light stripes projected on said photoconductive material.