Optical deflecting apparatus

Claim 2

An optical deflecting apparatus comprising a plurality of optical deflectors, each of which is provided with: (i) an optical waveguide formed of a material allowing propagation of surface acoustic waves therethrough, (ii) a first surface acoustic wave generating means for generating a first surface acoustic wave, which advances in a direction intersecting an optical path of a guided optical wave advancing inside of said optical waveguide and diffracts and deflects said guided optical wave, in said optical waveguide, and (iii) a second surface acoustic wave generating means for generating a second surface acoustic wave, which advances in a direction intersecting the optical path of said guided and diffracted optical wave and diffracts and deflects said guided and diffracted optical wave in a direction that amplifies the deflection caused by said diffraction, in said optical waveguide, wherein said first surface acoustic wave generating means and said second surface acoustic wave generating means are formed to continuously change the frequencies of said first surface acoustic wave and said second surface acoustic wave and the directions of advance thereof while satisfying the conditions of k1+ K1= k2, and k2+ K2= k3 wherein k1 and k2 respectively denote wave vectors of the guided optical wave before and after being diffracted by said first surface acoustic wave, k3 denotes a save vector of the guided optical wave after being diffracted by said second surface acoustic wave, and K1 and K2 respectively denote wave vectors of said first surface acoustic wave and said second surface acoustic wave, said optical waveguides of said optical deflectors being disposed so that the optical waves radiated out of said optical waveguides scan in a line with respect to each other on a predetermined surface, and scanning extremities of the adjacent radiated optical waves adjoin each other.

Claim 3

An apparatus as defined in claim 1 wherein each of said first surface acoustic wave generating means and said second surface acoustic wave generating means comprises a tilted-finger chirped interdigital transducer, in which transducer finger intervals are changed stepwise and the directions of the transducer fingers are changed stepwise, and a driver for applying an alternating voltage the frequency of which changes continuously to said tilted-finger chirped interdigital transducer.

Claim 4

An apparatus as defined in claim 1 wherein each of said first surface acoustic wave generating means and said second surface acoustic wave generating means comprises a curved-finger interdigital transducer, in which transducer finger intervals are changed stepwise and the respective transducer fingers are in a circular arc shape, and a driver for applying an alternating voltage the frequency of which changes continuously to said curved-finger chirped interdigital transducer.

Claim 5

An apparatus as defined in claim 2 wherein said first surface acoustic wave generating means and said second surface acoustic wave generating means are constituted to generate surface acoustic waves the frequencies of which change while attaining values equal to each other in a frequency range of f1 to f2, wherein f2=2f1, said chirped interdigital transducer which constitutes said first surface acoustic wave generating means is formed so that a transducer finger at a portion for generating said first surface acoustic wave having the frequency f1 makes an angle of θ/2 with respect to a direction of advance of a guided optical wave L1 incident upon said first surface acoustic wave, wherein θ denotes an angle of incidence of said guided optical wave L1 with respect to said first surface acoustic wave having the frequency f2, and said chirped interdigital transducer which constitutes said second surface acoustic wave generating means is formed so that the transducer fingers at portions for generating said second surface acoustic wave having the frequency f2 and said second surface acoustic wave having the frequency f1 respectively make an angle of 3θ and an angle of 3θ/2 with respect to the direction of advance of said guided optical wave L1.

Claim 6

An apparatus as defined in claim 3 wherein said first surface acoustic wave generating means and said second surface acoustic wave generating means are constituted to generate surface acoustic waves the frequencies of which change while attaining values equal to each other in a frequency range of f1 to f2, wherein f2=2f1, said curved-finger interdigital transducer which constitutes said first surface acoustic wave generating means is formed so that a transducer finger at a portion for generating said first surface acoustic wave having the frequency f1 makes an angle of θ/2 with respect to a direction of advance of a guided optical wave L1 incident upon said first surface acoustic wave, wherein θ denotes the angle of incidence of said guided optical wave L1 with respect to said first surface acoustic wave having the frequency f2, and said curved-finger interdigital transducer which constitutes said second surface acoustic wave generating means is formed so that the transducer fingers at portions for generating said second surface acoustic wave having the frequency f2 and said second surface acoustic wave having the frequency f1 respectively make an angle of 3θ and an angle of 3θ/2 with respect to the direction of advance of said guided optical wave L1.

Claim 7

An apparatus as defined in claim 4 or 5 wherein said interdigital transducers which respectively constitute said first surface acoustic wave generating means and said second surface acoustic wave generating means are operated by a single common driver.

Claim 8

An optical deflecting apparatus comprising: (i) an optical waveguide formed of a material allowing propagation of surface acoustic waves therethrough, (ii) a first surface acoustic wave generating means for generating a first surface acoustic wave, which advances in a direction intersecting an optical path of a first guided optical wave advancing inside of said optical waveguide and diffracts and deflects said first guided optical wave, in said optical waveguide, and (iii) a second surface acoustic wave generating means for generating a second surface acoustic wave, which advances in a direction intersecting an optical path of a second guided optical wave advancing inside of said optical waveguide and diffracts and deflects said second guided optical wave, in said optical waveguide, wherein said first surface acoustic wave generating means and said second surface acoustic wave generating means are disposed so that said first guided optical wave and said second guided optical wave radiated out of said optical waveguide scan in a line with respect to each other on a predetermined surface, and a scanning extremity of said first guided and radiated optical wave adjoin a scanning extremity of said second guided and radiated optical wave.

Claim 9

An optical deflecting apparatus comprising: (i) an optical waveguide formed of a material allowing propagation of surface acoustic waves therethrough, (ii) a first surface acoustic wave generating means for generating a first surface acoustic wave, which advances in a direction intersecting an optical path of a first guided optical wave advancing inside of said optical waveguide and diffracts and deflects said first guided optical wave, in said optical waveguide, and (iii) a second surface acoustic wave generating means for generating a second surface acoustic wave, which advances in a direction intersecting an optical path of a second guided optical wave advancing inside of said optical waveguide and diffracts and deflects said second guided optical wave, in said optical waveguide, wherein said first surface acoustic wave generating means and said second surface acoustic wave generating means are disposed so that said first guided optical wave and said second guided optical wave radiated out of said optical waveguide scan in a line with respect to each other on a predetermined surface, and a scanning extremity of said first guided and radiated optical wave adjoin a scanning extremity of said second guided and radiated optical wave.

Claim 10

An apparatus as defined in claim 7 wherein each of said first surface acoustic wave generating means and said second surface acoustic wave generating means comprises a tilted-finger chirped interdigital transducer, in which transducer finger intervals are changed stepwise and the directions of the transducer fingers are changed stepwise, and a driver for applying an alternating voltage the frequency of which changes continuously to said tilted-finger chirped interdigital transducer.

Claim 11

An apparatus as defined in claim 7 wherein each of said first surface acoustic wave generating means and said second surface acoustic wave generating means comprises a curved-finger interdigital transducer, in which transducer finger intervals are changed stepwise and the respective transducer fingers are in a circular arc shape, and a driver for applying an alternating voltage the frequency of which changes continuously to said curved-finger chirped interdigital transducer.

Claim 12

An optical deflecting apparatus comprising: (i) an optical waveguide formed of a material allowing propagation of surface acoustic waves therethrough, (ii) a first surface acoustic wave generating means for generating a first surface acoustic wave, which advances in a direction intersecting an optical path of a first guided optical wave advancing inside of said optical waveguide and diffracts and deflects said first guided optical wave, in said optical waveguide, (iii) a second surface acoustic wave generating means for generating a second surface acoustic wave, which advances in a direction intersecting an optical path of a second guided optical wave advancing inside of said optical waveguide and diffracts and deflects said second guided optical wave, in said optical waveguide, (iv) a third surface acoustic wave generating means for generating a third surface acoustic wave, which advances in a direction intersecting the optical path of said first guided optical wave diffracted by said first surface acoustic wave and diffracts and deflects said first guided and diffracted optical wave in a direction that amplifies the deflection caused by said diffraction, in said optical waveguide, and (v) a fourth surface acoustic wave generating means for generating a fourth surface acoustic wave, which advances in a direction intersecting the optical path of said second guided optical wave diffracted by said second surface acoustic wave and diffracts and deflects said second guided and diffracted optical wave in a direction that amplifies the deflection caused by said diffraction, in said optical waveguide, wherein said first surface acoustic wave generating means and said third surface acoustic wave generating means are formed to continuously change the frequencies of said first surface acoustic wave and said third surface acoustic wave and the directions of advance thereof while satisfying the conditions of k1+ K1= k2, and k2+ K2= k3 wherein k1 and k2 respectively denote wave vectors of said first guided optical wave before and after being diffracted by said first surface acoustic wave, k3 denotes a wave vector of said first guided optical wave after being diffracted by said third surface acoustic wave, and K1 and K2 respectively denote wave vectors of said first surface acoustic wave and said third surface acoustic wave,

Claim 13

An optical deflecting apparatus comprising: (i) an optical waveguide formed of a material allowing propagation of surface acoustic waves therethrough, (ii) a first surface acoustic wave generating means for generating a first surface acoustic wave, which advances in a direction intersecting an optical path of a first guided optical wave advancing inside of said optical waveguide and diffracts and deflects said first guided optical wave, in said optical waveguide, (iii) a second surface acoustic wave generating means for generating a second surface acoustic wave, which advances in a direction intersecting an optical path of a second guided optical wave advancing inside of said optical waveguide and diffracts and deflects said second guided optical wave, in said optical waveguide, (iv) a third surface acoustic wave generating means for generating a third surface acoustic wave, which advances in a direction intersecting the optical path of said first guided optical wave diffracted by said first surface acoustic wave and diffracts and deflects said first guided and diffracted optical wave in a direction that amplifies the deflection caused by said diffraction, in said optical waveguide, and (v) a fourth surface acoustic wave generating means for generating a fourth surface acoustic wave, which advances in a direction intersecting the optical path of said second guided optical wave diffracted by said second surface acoustic wave and diffracts and deflects said second guided and diffracted optical wave in a direction that amplifies the deflection caused by said diffraction, in said optical waveguide, wherein said first surface acoustic wave generating means and said third surface acoustic wave generating means are formed to continuously change the frequencies of said first surface acoustic wave and said third surface acoustic wave and the directions of advance thereof while satisfying the conditions of k1+ K1= k2, and k2+ K2= k3 wherein k1 and k2 respectively denote wave vectors of said first guided optical wave before and after being diffracted by said first surface acoustic wave, k3 denotes a wave vector of said first guided optical wave after being diffracted by said third surface acoustic wave, and K1 and K2 respectively denote wave vectors of said first surface acoustic wave and said third surface acoustic wave,

Claim 14

said second surface acoustic wave generating means and said fourth surface acoustic wave generating means are formed to continuously change the frequencies of said second surface acoustic wave and said fourth surface acoustic wave and the directions of advance thereof while satisfying the conditions of k4+ K3= k5, and k5+ K4= k6 wherein k4 and k5 respectively denote wave vectors of said second guided optical wave before and after being diffracted by said second surface acoustic wave, k6 denotes a wave vector of said second guided optical wave after being diffracted by said fourth surface acoustic wave, and K3 and K4 respectively denote wave vectors of said second surface acoustic wave and said fourth surface acoustic wave, and said first surface acoustic wave generating means, said second surface acoustic wave generating means, said third surface acoustic wave generating means, and said fourth surface acoustic wave generating means are disposed so that said first guided optical wave and said second guided optical wave radiated out of said optical waveguide scan in a line with respect to each other on a predetermined surface, and a scanning extremity of said first guided and radiated optical wave adjoin a scanning extremity of said second guided and radiated optical wave.

Claim 15

said second surface acoustic wave generating means and said fourth surface acoustic wave generating means are formed to continuously change the frequencies of said second surface acoustic wave and said fourth surface acoustic wave and the directions of advance thereof while satisfying the conditions of k4+ K3= k5, and k5+ K4= k6 wherein k4 and k5 respectively denote wave vectors of said second guided optical wave before and after being diffracted by said second surface acoustic wave, k6 denotes a wave vector of said second guided optical wave after being diffracted by said fourth surface acoustic wave, and K3 and K4 respectively denote wave vectors of said second surface acoustic wave and said fourth surface acoustic wave, and said first surface acoustic wave generating means, said second surface acoustic wave generating means, said third surface acoustic wave generating means, and said fourth surface acoustic wave generating means are disposed so that said first guided optical wave and said second guided optical wave radiated out of said optical waveguide scan in a line with respect to each other on a predetermined surface, and a scanning extremity of said first guided and radiated optical wave adjoin a scanning extremity of said second guided and radiated optical wave.

Claim 16

An apparatus as defined in claim 10 wherein each of said first surface acoustic wave generating means, said second surface acoustic wave generating means, said third surface acoustic wave generating means, and said fourth surface acoustic wave generating means comprises a tilted-finger chirped interdigital transducer, in which transducer finger intervals are changed stepwise and the directions of the transducer fingers are changed stepwise, and a driver for applying an alternating voltage the frequency of which changes continuously to said tilted-finger chirped interdigital transducer.

Claim 17

An apparatus as defined in claim 10 wherein each of said first surface acoustic wave generating means, said second surface acoustic wave generating means, said third surface acoustic wave generating means, and said fourth surface acoustic wave generating means comprises a curved-finger interdigital transducer, in which transducer finger intervals are changed stepwise and the respective transducer fingers are in a circular arc shape, and a driver for applying an alternating voltage the frequency of which changes continuously to said curved-finger chirped interdigital transducer.

Claim 18

An apparatus as defined in claim 11 wherein the m'th surface acoustic wave generating means and the m+2'th surface acoustic wave generating means, where m=1 and/or 2, are constituted to generate surface acoustic waves the frequencies of which change while attaining values equal to each other in a frequency range of f1 to f2, wherein f2≃2f1, said chirped interdigital transducer which constitutes said m'th surface acoustic wave generating means is formed so that a transducer finger at a portion for generating said surface acoustic wave having the frequency f1 makes an angle of η/2 with respect to a direction of advance of an m'th guided optical wave L1 incident upon said m'th surface acoustic wave, wherein θ denotes an angle of incidence of said guided optical wave L1 with respect to said m'th surface acoustic wave having the frequency f2, and said chirped interdigital transducer which constitutes said m+2'th surface acoustic wave generating means is formed so that the transducer fingers at portions for generating said surface acoustic wave having the frequency f2 and said surface acoustic wave having the frequency f1 respectively make an angle of 3θ and an angle of 3θ/2 with respect to the direction of advance of said guided optical wave L1.

Claim 19

An apparatus as defined in claim 12 wherein the m'th surface acoustic wave generating means and the m+2'th surface acoustic wave generating means, where m=1 and/or 2, are constituted to generate surface acoustic waves the frequencies of which change while attaining values equal to each other in a frequency range of f1 to f2, wherein f2=2f1, said curved-finger interdigital transducer which constitutes said m'th surface acoustic wave generating means is formed so that a transducer finger at a portion for generating said surface acoustic wave having the frequency f1 makes an angle of θ/2 with respect to a direction of advance of an m'th guided optical wave L1 incident upon said m'th surface acoustic wave, wherein θ denotes an angle of incidence of said guided optical wave L1 with respect to said m'th surface acoustic wave having the frequency f2, and said curved-finger interdigital transducer which constitutes said m+2'th surface acoustic wave generating means is formed so that the transducer fingers at portions for generating said surface acoustic wave having the frequency f2 and said surface acoustic wave having the frequency f1 respectively make an angle of 3θ and an angle of 3θ/2 with respect to the direction of advance of said guided optical wave L1.

Claim 20

An apparatus as defined in claim 13 or 14 wherein said interdigital transducers which respectively constitute said m'th surface acoustic wave generating means and said m+2'th surface acoustic wave generating means are operated by a single common driver.

Claim 21

An optical deflecting apparatus comprising: (i) an optical waveguide formed of a material allowing propagation of surface acoustic waves therethrough, (ii) a first surface acoustic wave generating means for generating a first surface acoustic wave, which advances in a direction intersecting an optical path of a first guided optical wave advancing inside of said optical waveguide and diffracts and deflects said first guided optical wave, in said optical waveguide, and (iii) a second surface acoustic wave generating means for generating a second surface acoustic wave, which advances in a direction intersecting an optical path of a second guided optical wave advancing inside of said optical waveguide and diffracts and deflects said second guided optical wave, in said optical waveguide, wherein said first surface acoustic wave generating means and said second surface acoustic wave generating means are disposed so that said first guided optical wave and said second guided optical wave radiated out of said optical waveguide scan without overlapping each other on a predetermined surface.

Claim 22

An optical deflecting apparatus comprising: (i) an optical waveguide formed of a material allowing propagation of surface acoustic waves therethrough, (ii) a first surface acoustic wave generating means for generating a first surface acoustic wave, which advances in a direction intersecting an optical path of a first guided optical wave advancing inside of said optical waveguide and diffracts and deflects said first guided optical wave, in said optical waveguide, and (iii) a second surface acoustic wave generating means for generating a second surface acoustic wave, which advances in a direction intersecting an optical path of a second guided optical wave advancing inside of said optical waveguide and diffracts and deflects said second guided optical wave, in said optical waveguide, wherein said first surface acoustic wave generating means and said second surface acoustic wave generating means are disposed so that said first guided optical wave and said second guided optical wave radiated out of said optical waveguide scan without overlapping each other on a predetermined surface.

Claim 23

An apparatus as defined in claim 16 wherein each of said first surface acoustic wave generating means and said second surface acoustic wave generating means comprises a tilted-finger chirped interdigital transducer, in which transducer finger intervals are changed stepwise and the directions of the transducer fingers are changed stepwise, and a driver for applying an alternating voltage the frequency of which changes continuously to said tilted-finger chirped interdigital transducer.

Claim 24

An apparatus as defined in claim 16 wherein each of said first surface acoustic wave generating means and said second surface acoustic wave generating means comprises a curved-finger interdigital transducer, in which transducer finger intervals are changed stepwise and the respective transducer fingers are in a circular arc shape, and a driver for applying an alternating voltage the frequency of which changes continuously to said curved-finger chirped interdigital transducer.

Claim 25

An optical deflecting apparatus comprising: (i) an optical waveguide formed of a material allowing propagation of surface acoustic waves therethrough, (ii) a first surface acoustic wave generating means for generating a first surface acoustic wave, which advances in a direction intersecting an optical path of a first guided optical wave advancing inside of said optical waveguide and diffracts and deflects said first guided optical wave, in said optical waveguide, (iii) a second surface acoustic wave generating means for generating a second surface acoustic wave, which advances in a direction intersecting an optical path of a second guided optical wave advancing inside of said optical waveguide and diffracts and deflects said second guided optical wave, in said optical waveguide, (iv) a third surface acoustic wave generating means for generating a third surface acoustic wave, which advances in a direction intersecting the optical path of said first guided optical wave diffracted by said first surface acoustic wave and diffracts and deflects said first guided and diffracted optical wave in a direction that amplifies the deflection caused by said diffraction, in said optical waveguide, and (v) a fourth surface acoustic wave generating means for generating a fourth surface acoustic wave, which advances in a direction intersecting the optical path of said second guided optical wave diffracted by said second surface acoustic wave and diffracts and deflects said second guided and diffracted optical wave in a direction that amplifies the deflection caused by said diffraction, in said optical waveguide, wherein said first surface acoustic wave generating means and said third surface acoustic wave generating means are formed to continuously change the frequencies of said first surface acoustic wave and said third surface acoustic wave and the directions of advance thereof while satisfying the conditions of k1+ K1= k2, and k2+ K2= k3, wherein k1 and k2 respectively denote wave vectors of said first guided optical wave before and after being diffracted by said first surface acoustic wave, k3 denotes a wave vector of said first guided optical wave after being diffracted by said third surface acoustic wave, and K1 and K2 respectively denote wave vectors of said first surface acoustic wave and said third surface acoustic wave, said second surface acoustic wave generating means and said fourth surface acoustic wave generating means are formed to continuously change the frequencies of said second surface acoustic wave and said fourth surface acoustic wave and the directions of advance thereof while satisfying the conditions of k4+ K3= k5, and k5+ K4= k6 wherein k4 and k5 respectively denote wave vectors of said second guided optical wave before and after being diffracted by said second surface acoustic wave, k6 denotes a wave vector of said second guided optical wave after being diffracted by said fourth surface acoustic wave, and K3 and K4 respectively denote wave vectors of said second surface acoustic wave and said fourth surface acoustic wave, and said first surface acoustic wave generating means, said second surface acoustic wave generating means, said third surface acoustic wave generating means, and said fourth surface acoustic wave generating means are disposed so that said first guided optical wave and said second guided optical wave radiated out of said optical waveguide scan without overlapping each other on a predetermined surface.

Claim 26

An optical deflecting apparatus comprising: (i) an optical waveguide formed of a material allowing propagation of surface acoustic waves therethrough, (ii) a first surface acoustic wave generating means for generating a first surface acoustic wave, which advances in a direction intersecting an optical path of a first guided optical wave advancing inside of said optical waveguide and diffracts and deflects said first guided optical wave, in said optical waveguide, (iii) a second surface acoustic wave generating means for generating a second surface acoustic wave, which advances in a direction intersecting an optical path of a second guided optical wave advancing inside of said optical waveguide and diffracts and deflects said second guided optical wave, in said optical waveguide, (iv) a third surface acoustic wave generating means for generating a third surface acoustic wave, which advances in a direction intersecting the optical path of said first guided optical wave diffracted by said first surface acoustic wave and diffracts and deflects said first guided and diffracted optical wave in a direction that amplifies the deflection caused by said diffraction, in said optical waveguide, and (v) a fourth surface acoustic wave generating means for generating a fourth surface acoustic wave, which advances in a direction intersecting the optical path of said second guided optical wave diffracted by said second surface acoustic wave and diffracts and deflects said second guided and diffracted optical wave in a direction that amplifies the deflection caused by said diffraction, in said optical waveguide, wherein said first surface acoustic wave generating means and said third surface acoustic wave generating means are formed to continuously change the frequencies of said first surface acoustic wave and said third surface acoustic wave and the directions of advance thereof while satisfying the conditions of k1+ K1= k2, and k2+ K2= k3, wherein k1 and k2 respectively denote wave vectors of said first guided optical wave before and after being diffracted by said first surface acoustic wave, k3 denotes a wave vector of said first guided optical wave after being diffracted by said third surface acoustic wave, and K1 and K2 respectively denote wave vectors of said first surface acoustic wave and said third surface acoustic wave, said second surface acoustic wave generating means and said fourth surface acoustic wave generating means are formed to continuously change the frequencies of said second surface acoustic wave and said fourth surface acoustic wave and the directions of advance thereof while satisfying the conditions of k4+ K3= k5, and k5+ K4= k6 wherein k4 and k5 respectively denote wave vectors of said second guided optical wave before and after being diffracted by said second surface acoustic wave, k6 denotes a wave vector of said second guided optical wave after being diffracted by said fourth surface acoustic wave, and K3 and K4 respectively denote wave vectors of said second surface acoustic wave and said fourth surface acoustic wave, and said first surface acoustic wave generating means, said second surface acoustic wave generating means, said third surface acoustic wave generating means, and said fourth surface acoustic wave generating means are disposed so that said first guided optical wave and said second guided optical wave radiated out of said optical waveguide scan without overlapping each other on a predetermined surface.

Claim 27

An apparatus as defined in claim 19 wherein each of said first surface acoustic wave generating means, said second surface acoustic wave generating means, said third surface acoustic wave generating means, and said fourth surface acoustic wave generating means comprises a tilted-finger chirped interdigital transducer, in which transducer finger intervals are changed stepwise and the directions of the transducer fingers are changed stepwise, and a driver for applying an alternating voltage the frequency of which changes continuously to said tilted-finger chirped interdigital transducer.

Claim 28

An apparatus as defined in claim 19 wherein each of said first surface acoustic wave generating means, said second surface acoustic wave generating means, said third surface acoustic wave generating means, and said fourth surface acoustic wave generating means comprises a curved-finger interdigital transducer, in which transducer finger intervals are changed stepwise and the respective transducer fingers are in a circular arc shape, and a driver for applying an alternating voltage the frequency of which changes continuously to said curved-finger chirped interdigital transducer.

Claim 29

An apparatus as defined in claim 20 wherein the m'th surface acoustic wave generating means and the m+2'th surface acoustic wave generating means, where m=1, and/or 2, are constituted to generate surface acoustic waves the frequencies of which change while attaining values equal to each other in a frequency range of f1 to f2, wherein f2=2f1, said chirped interdigital transducer which constitutes said m'th surface acoustic wave generating means is formed so that a transducer finger at a portion for generating said surface acoustic wave having the frequency f1 makes an angle of θ/2 with respect to a direction of advance of an m'th guided optical wave L1 incident upon said m'th surface acoustic wave, wherein θ denotes an angle of incidence of said guided optical wave L1 with respect to said m'th surface acoustic wave having the frequency f2, and said chirped interdigital transducer which constitutes said m+2'th surface acoustic wave generating means is formed so that the transducer fingers at portions for generating said surface acoustic wave having the frequency f2 and said surface acoustic wave having the frequency f1 respectively make an angle of 3θ and an angle of 3θ/2 with respect to the direction of advance of said guided optical wave L1.

Claim 30

An apparatus as defined in claim 21 wherein the m'th surface acoustic wave generating means and the m+2'th surface acoustic wave generating means, where m=1 and/or 2, are constituted to generate surface acoustic waves the frequencies of which change while attaining values equal to each other in a frequency range of f1 to f2, wherein f2≃2f1, said curved-finger interdigital transducer which constitutes said m'th surface acoustic wave generating means is formed so that a transducer finger at a portion for generating said surface acoustic wave having the frequency f1 makes an angle of θ/2 with respect to a direction of m'th surface acoustic wave, wherein θ denotes an angle of incidence of said guided optical wave L1 with respect to said m'th surface acoustic wave having the frequency f2, and said curved-finger interdigital transducer which constitutes said m+2'th surface acoustic wave generating means is formed so that the transducer fingers at portions for generating said surface acoustic wave having the frequency f2 and said surface acoustic wave having the frequency f1 respectively make an angle of 38 and an angle of 3θ/2 with respect to the direction of advance of said guided optical wave L1.

Claim 31

An apparatus as defined in claim 22 or 23 wherein said interdigital transducers which respectively constitute said m'th surface acoustic wave generating means and said m+2'th surface acoustic wave generating means are operated by a single common driver.