<title>Design and performance of GaAs-based guided-wave heterodyne circuits for signal processing</title>

Abstract

In this work are presented the design parameters and performance of a guided-wave spectrum analyzer based on a multilayered ZnO/AlxGaixAs/AlyGaiyAs/GaAs structure for heterodyne detection of spread spectrum signals. The adopted circuit configuration includes a double integrated collimating grating having non linear groove profiles, an acousto-optic (AO) Bragg cell, a concave frating lens, a focusing grating lens and an output photodiode array. The optical structure has been optimized as a function of the layer thickness, and Al title in order to obtain improved performance of the circuit in terms of 3-dB Bragg bandwidth (up to 185 MHz), surface acoustic wave (SAW) power consumption (less than 3 mW), frequency resolution (less than 1.5 MHz), and single-tone dynamic range (about 56 dB). The number of channels has been found equal to 1 12 and 125 in the two structures under investigation, respectively. The calculated single-and double-tone dynamic range are reduced of about 40% with respect to the corresponding dynamic ranges of the homodyne architecture. All the design parameters have been calculated for each integrated component of the circuit at the free-space optical wavelength of 0.85 m.