CONFERENCE REVIEW

ISSY LES MOULINEAUX, FRANCE--Several high-frequency acousto-optic devices based on gallium arsenide (GaAs) and indium phosphide (InP) have been designed and tested by researchers at France Telecom and CNET (Paris, France). In the 1.3- and 1.5-µm wavelength ranges, the devices exhibit a significant increase in acousto-optic properties at near-resonance conditions. Using lithium niobate (LiNbO3) transducer technology with central frequencies of 800 MH¥and 8 GHz, researchers demonstrated th

CONFERENCE REVIEW

Semiconductors improve A-O device performance

Roland Roux

ISSY LES MOULINEAUX, FRANCE--Several high-frequency acousto-optic devices based on gallium arsenide (GaAs) and indium phosphide (InP) have been designed and tested by researchers at France Telecom and CNET (Paris, France). In the 1.3- and 1.5-µm wavelength ranges, the devices exhibit a significant increase in acousto-optic properties at near-resonance conditions. Using lithium niobate (LiNbO3) transducer technology with central frequencies of 800 MH¥and 8 GHz, researchers demonstrated that 100% of transmitted light can be deflected in a pulse. These results can be extended to other III-V and II-VI (binary, ternary, and quaternary) bulk and integrated components of acousto-optic devices.

This report was presented at the 10th topical meeting of the European Optical Society (Advances in Acousto-Optics AA-O `96, June 6-7, 1996) held at CNET in Issy les Moulineaux. The conference covered all aspects of interactions between ultrasound and light for a range of applications such as modulation-deflection, new materials characterization, and ultrasound generation.

A grou¥from the Institut d`Electronique et de Micro-Electronique du Nord Université de Valencienne (France) reported attempts to fabricate an acousto-optic deflector for laser gyroscopic applications. In this device two acousto-optic interactions occur successively in order to obtain simultaneous frequency variation in opposite directions (see figure). The paper confirms that this approach allows easier and better measurement accuracy than with conventional components.

In the field of spectral analysis, a wideband multichannel acousto-optic spectrometer for radio astronomy at millimeter and submillimeter wavelengths was described by researchers from Photonic Systems Incorporated, (Melbourne, FL). Their four-channel spectrometer can process signals from four separate sources simultaneously. The bandwidth of each channel is 1 GH¥with a frequency resolution of 1 MHz, thus providing simultaneous processing of more than 4000 1-MH¥channels.

In a session on acousto-optic tunable filters, researchers from ALENIA Research Division (Rome, Italy), discussed a high-resolution integrated optical acousto-optic tunable filter (AOTF) based on a LiNbO3 crystal operating in the 1.5- and 1.3-µm ranges with FWHM of less than 0.45 nm at 1.35 µm. The device can be used in fiberoptic multiple-wavelength communications to multiplex and demultiplex the signals, as well as in fiberoptic Bragg grating sensors for optical signal processing and as a high-resolution high-speed optical spectrometer.

Researchers from the Lasers and Optical Systems Engineering Centre, University of Glasgow (Glasgow, UK), described an automated page-oriented angle-multiplexed volume holographic memory recording system; a photorefractive crystal, Fe:LiNbO3, was the optical memory medium. This system is part of a larger high-speed hybrid optical and electronic correlator under construction.

According to the authors of a report from Science and Production Corporation "Vega M" (Moscow, Russia), combining holography with acousto-optics provides a memory system with high capacity and high data-access rates. The time integrating and collinear heterodyning of holograms eliminates signal crosstalk and permits low-power CW lasers to be used effectively. This device can be successfully applied in television and other wideband radio engineering systems.

The conference was organized by the Societé Françoise d`Optique (SFO) and the European Optical Society (EOS); sponsors included the Centre National d`Etudes des Telecommunications (CNET), Delegation Generale a l`Azurement (DRET/DGA), Automates et Automatisme (St. Remy las Chevreuses, France), and Coherent SA (Orsay, France).

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