SU1224775A1 - Accoustical-optical modulator based on surface acoustic waves - Google Patents

Abstract

This invention relates to the field of computing. The invention makes it possible to increase the diffraction efficiency per unit of acoustic power by performing a modulator optical glider waveguide in the form of a truncated from two sides of a thin-walled body of rotation, in particular a cylinder or a cone. In this case, the electroacoustic transducer is placed on one of the ends of the body of rotation. In the case of a waveguide in the form of a cone transducer size. is located at the end opposite the base of the cone, and the light input and output prisms are made in the form of a single isosceles prism placed at the base of the cone. As a result of the light propagating in a spiral, the length of the interaction between the light and the acoustic wave increases, which increases the diffraction efficiency. 3 hp f-ly, 3 ill. i (L N5 to 4 SP

Description

The invention relates to acousto-optic devices and is intended for use in optical information processing devices.

The purpose of the present invention is to increase the diffraction efficiency per unit acoustic power. A further object of the invention is also to extend the frequency band and simplify the design.

Figure 1 shows a variant of the modulator circuit in a cylindrical design; figure 2 - the same, in conical design; fig.Z - the same, with the combination of input and output prisms.

Acousto-optic modulator (AOM) on surface acoustic waves (SAW) contains a planar optical waveguide 1, made in the form of a thin-walled rotational body truncated from two sides, in particular a cylinder (fig.) Or a cone (figs. 2 and 3) electroacoustic transducer 2 and the prism of the input 3 and output 4 light. The figures also show the input optical beam 5, the direction of propagation of the surfactant 6, the diffracted 7 and the undifferented 8 rays,

AOM on surfactant works as follows.

An optical beam is incident on the input light prism 3 in such a way that it crosses the SAW front at a Bragg angle 0. From the input prism 3 to the output prism 4, the light in waveguide 1 will be. spread in a spiral. The length of the interaction will be determined by the number of turns N, which will make the light between the input and output prisms

L -

 R cos in where R is the radius of the cylinder,

In Bragg mode, diffraction efficiency 1 is expressed in terms of acoustic power P and interaction length as follows;

 sin (

 e

In the described AOM on a surfactant, the implementation of a planar waveguide in the form of a cylindrical surface provides an increase in the length of the interaction of light with sound, which reduces the acoustic power required to obtain high diffraction efficiency. The interaction length in the interaction of light with diverging acoustic waves is directly proportional to the aperture of the electroacoustic surfactant converter and proportional to the divergence of acoustic waves. The if frequency band in such an AOM is directly proportional to the divergence of the acoustic waves.

In FIG. 2, the light entering the prism 3 of the input optical beam 5 falls so that the front of the divergent SAW is intersected at an angle Cf. Moreover, when the beam of light moves from the input prism to the output prism, the angle (varies within,

The range of variation of the angle cf (l0) is determined from the required band of the device. The interaction length L will be determined by the number of turns that will make light from the input prism to the output prism.

When AON is designed for divergent surfactants (Fig. 3), the input optical beam 5 returns to prism 3 after several turns. Moreover, during its movement, the front of the surfactant will cross the light beam at an angle tf varying in the range -iS tfSuS. An AOM for a divergent surfactant, the implementation of a planar waveguide in the form of a conical surface provides an increase in the length of the interaction of light with sound, which reduces the acoustic power required to obtain a high diffraction efficiency. Combining input and output prisms into one isosceles prism allows us to simplify the construction of an AOM on divergent surfactants,

Claims (4)

1. An acousto-optic surface acoustic wave modulator containing a planar optical waveguide, an electroacoustic transducer, and a light input and output prism placed on the surface of an optical waveguide; the propagation of acoustic and optical waves is oriented under the Bragg angle, characterized in that, in order to increase the diffraction efficiency per unit of acoustic power, the planar optical waveguide is made in the form of a thin-walled body truncated rotation, on one end of which an electro-acoustic transducer is placed, 2, Populator modulator 1, o-ticking by that the rotation body is a cylinder. 3. Modulator according to claim 1, characterized in that, in order to expand the frequency band due to diverging acoustic waves, the body of rotation is a truncated cone, with the electroacoustic transducer placed on the end opposite to the base of the cone. 4. The modulator according to claims 1 and 3, which is based on the fact that, in order to simplify the design, the input prisms and the light output is made in the form of an isosceles prism placed at the base of the cone. (l) Ui.i 7 (Rig.y. Fi.Z