Abstract: An amorphous film of As.sub.2 S.sub.5 on a substrate is disclosed for use in various optical applications. The film can be shaped as a lens to focus light. By mounting an acoustic transducer on the film to produce surface or bulk acoustic waves light moving in the film can be deflected or modulated respectively. The film can also be used in anti-reflective, high reflectivity, and photoconductive coatings.

Abstract: The compound Tl.sub.3 PSe.sub.4 is disclosed. Non-conducting single crystals of the compound are prepared which have outstanding acousto-optical properties including an exceptionally high acousto-optical figure of merit. The crystals are used in various acousto-optical devices including a display device, a laser modulator, a non-collinear acousto-optical filter, and an acoustic delay line.

Abstract: An acoustic surface wave device is disclosed which comprises a crystal of Tl.sub.3 VS.sub.4, Tl.sub.3 NbS.sub.4, or mixtures thereof having at least one surface at least 1/2 cm long, a surface wave generating transducer mounted on the surface, and a surface wave receiving transducer mounted on the surface positioned to receive a surface wave generated by the surface wave generating transducer.The device transmits surface waves at a low velocity and high coupling efficiency and can be used in a delay line, a filter, an FM discriminator, an oscillator, or other device.

Abstract: Single crystals of Tl.sub.3 VS.sub.4 and Tl.sub.3 NbS.sub.4 are disclosed which have useful acousto-optical properties, including low acoustic velocities and high acousto-optical figure of merit. They are used in acousto-optical devices such as a display device, a laser modulator, a non-collinear tunable filter, and an acousto-optical delay line.

Abstract: A crystal resonator is disclosed of a single crystal of the approximate composition Tl.sub.3 BX.sub.4 having two parallel surfaces normal to a zero temperature coefficient of frequency direction and having an electrode mounted on each surface, where B is vanadium, niobium, or tantalum, and X is sulfur or selenium. A filter is disclosed of a crystal resonator coupled to a capacitor or more than one crystal resonator in series each coupled to a capacitor. A voltage controlled crystal oscillator resonator is disclosed of a crystal resonator in parallel with an inductor and a varactor.

Abstract: Single crystals of Tl.sub.3 TaS.sub.4 and Tl.sub.3 TaSe.sub.4 are disclosed which have useful acousto-optical properties, including low acoustic velocities and high acousto-optical figures of merit. They are used in acousto-optical devices such as a display device, a laser modulator, a non-collinear tunable filter, an acousto-optical delay line, and an acousto-optical waveguide modulator.

Abstract: Crystals or Tl.sub.3 VS.sub.4, Tl.sub.3 VSe.sub.4, Tl.sub.3 NbS.sub.4, Tl.sub.3 NbSe.sub.4, Tl.sub.3 TaS.sub.4, and Tl.sub.3 TaSe.sub.4 are disclosed which have a surface containing of normal to a zero temperature coefficient of delay direction. The crystals are used to transmit acoustic waves in surface and bulk wave devices.

Abstract: An acoustic surface wave device is disclosed which comprises a crystal of Tl.sub.3 TaS.sub.4, Tl.sub.3 TaSe.sub.4, or mixtures thereof having at least one surface suitable for the propagation of surface waves, a surface wave generating transducer mounted on the surface, and a surface wave receiving transducer mounted on the surface positioned to receive a surface wave generated by the surface wave generating transducer.The device transmits surface waves at a low velocity and high coupling efficiency and can be used in a delay line, a filter, an FM discriminator, an oscillator, or other device.

Abstract: An optical waveguide modulator is disclosed which uses single crystals of TlGaSe.sub.2 or TlInS.sub.2. The optical waveguide modulator is used to impress a signal upon a light beam traveling in a waveguide. Monochromatic light is guided along a thin plate of the crystal. Acoustic waves are generated which move across the thickness of the crystal, modulating the light. The frequency, polarization, or mode of the light can be modulated by the acoustic waves.

Abstract: The compound Tl.sub.3 PSe.sub.4 is disclosed. Non-conducting single crystals of the compound are prepared which have outstanding acousto-optical properties including an exceptionally high acousto-optical figure of merit. The crystals are used in various acousto-optical devices including a display device, a laser modulator, a non-collinear acousto-optic filter, and an acoustic delay line.