Abstract: The object of the present invention is to present an acoustooptical modulator without ripples in its wavelength loss characteristics. In order to achieve this objective, the present invention provides an acoustooptical body 8 having a piezoelectric vibrator supplying, for example, ultrasonic vibration, to modulate the incident optical signal, an acoustooptical medium rotated 90.degree. on the crystal axis of the acoustooptical medium upon which the optical signal emitted from acoustooptical medium is incident, and eliminates the polarization mode scattering caused the birefringence of both acoustooptical medium and acoustooptical medium.

Abstract: There is disclosed a solid ultrasonic delay line which comprises a delay medium having two parallel major faces and at least three end faces intersecting the major faces, an input transducer bonded to one of the end faces and polarized in a direction parallel to the major faces for transmitting an ultrasonic signal in a shear mode into the delay medium, and an output transducer bonded to one of the end faces for converting the ultrasonic signal having propagated through the delay medium into an electrical signal. The input and output transducers have boundary surfaces lying flush with the two major faces of the delay medium, the major faces and the boundary surfaces being ground to a surface roughness which is one-twentieth or smaller of the wavelength of the ultrasonic signal propagating through the delay medium.