Real Time Methods for Wideband Data Processing Based on Surface Acoustic Waves

Abstract

The newly developed methods enjoy the advantages of an optical channel for data transfer (parallel data processing in real time, high operating speed, and noise immunity) and the advantages typical of integrated optics (compactness, low power consumption, high sensitivity in information signal processing, stability against external action, and the possibility of using the batch-fabrication technique). The aforesaid advantages account for the wide use of waveguide acoustooptic (AO) units (WAOU) in computing, fiber-optic, telecommunication, and other photonic systems [1-3]. Conventional WAOUs are constructed from 3D elements. However, size, power consumption, and sensitivity to environmental conditions (vibrations, temperature variations, etc.) set limits on the applications of these devices. The WAOU (typical functional scheme is shown on fig. 1) is based on the waveguide AO Bragg diffraction of the modulated light beam on a modulated surface acoustic wave (SAW) and the registration of this diffraction image. One of the main WAOU parameters is product TAΔf, where TA = Wopt/V is the maximum delay time, which is known to be equivalent to the propagation time of the SAW leading edge through the optical beams, where Wopt is the optical beam width, Vthe SAW velocity, and Δf is the working frequency band. The x axis is directed along the propagation of the optical beam, the y axis is orthogonal to the waveguide plane and directed to its depth, and the z coordinate is perpendicular to the direction of propagation of the optical beam. SAW operates as an optical driving transparency [4,5]. It executes following important operations: changing of deflection angle by means of change of SAW frequency (frequency of applied RF-signal) this property is used for optical deflectors, scanners, switches; changing of intensity of diffracted beam by means of change of power of applied RFsignal this property is used for amplitude modulation; changing of frequency of diffracted beam depended on changing of SAW frequency frequency modulation. SAW is generated with an electro-acoustical transducer [6]. The transducer type is usual inter digital transducer (IDT).