All acoustooptic (AO) devices are based on the inherent nonlinear dependence of the light diffraction efficiency as a function the acoustical wave intensity. In AO devices using a single frequency acoustic wave it is easy to be taken into account to describe all functional properties and limits of the first order diffraction. But in many practical devices using multi-frequency sounds like AO signal processors or multipoint AO deflectors the description are a very complicated, because of a very strong frequency intermodulations. These effects give functional disadvantages in the AO implementations- the decrease of the first order diffraction efficiency maximum to much less than 100%, the appearance of spurious orders and etc. In this work there were developed the theoretical arguments for the possibility to have the appropriate signal dynamic predistortions to have a serious change of mentioned intermodulations and to obtain some advances in limitations of many existing AO devices. The proposal uses the new technique by authors for synthesis and programmable dynamic changes of all RF signals performing the preliminary electronic signal treatment to cancel a certain diffraction modes. The experimental verifications with AO modulators based on TeO2 crystal have been performed. With use of the analogue third order polynomial RF synthesizer there were obtained a good suppression up to 10-15 dB of two-tone second-order intermodulations in area of second order diffraction and two-tone third order spurious modes in the first order diffraction area, in accordance with proper theoretical calculations. There was also verified new technique providing maximal optical power in multi beams laser diagram. In TeO2 AO modulators the growth of the efficiency of two-beam He-Ne laser about 14% was obtained.
KEYWORDS: Telecommunications, Signal processing, Signal generators, Computing systems, Computer simulations, Mobile communications, Receivers, Radio propagation, Interfaces, Human-machine interfaces
New generation of systems cellular communication are strongly interested in systems with spread spectrum. The work on use of solid state elements in mobile communication system came before investigations of such systems. The important part of project system investigation is computer modeling behavior of system in urban situation. Here the concept of radio interface for system CTDMA verification and testing that system was presented. It is specially convenient to study main signal processing part convolver SAW.
There are analyzed potential parameters of the planar AO modulators for space-and- wavelength photonic switching. We consider different schemes of superfast AO switching with capability up to 1015 switch/sec within one multichannel guided wave device. On the basis of the experimentally achieved parameters of the planar Ti:LiNbO3 AO modulators we discuss a few prospective applications in high speed digital multipliers, commutators for optoelectronic super computers and associative memory systems.
For optically resonant systems, the intermodulation amplitudes of the 2nd and 3rd orders in approximation of small diffraction efficiency for the two main AO interaction regimes: 'thin' and 'thick' gratings are for the first time calculated. It is shown, that the photoelastic nonlinearity causes in general case the complexity of intermodulations. However, under certain conditions, the effect of compensated intermodulation can take place. It yields to the possibility of remarkable growth of the dynamic ragne value which is a great importance parameter for many AO devices.
There are analyzed potential parameters of the planar AO modulators for implementations to the optical commutation. It considers different schemes of superfast AO commutators performing up to 1015 switchings per second within one multichannel guided wave device. On the basis of the experimentally verified parameters of the planar Ti:LiNbO3 AO modulators it discusses a few perspective applications in the high speed digital multipliers, the commutators for the optoelectronic super computers, and the associative memory systems.
This paper is devoted to the description of the basic properties of the collinear acousto-optic (AO) interaction in planar waveguides and its applications recently developed for different multichannel AO devices performing light deflection, spectrum analysis, spectrum multiplexing and demultiplexing, etc.
Recently, there appeared in acousto-optics (AO) a tendency to develop the optical information processing technology based on AO spatial light modulators, which are very promising in relation to very fast analog signal processing and algebraic data processing with digital accuracy. The best widely distinguished way to win many other marketing counterparts lies in the performance of AO interactions in guided wave structures with highly developed planar technology. In contrast to numerous developments devoted to guided wave AO devices the collinear ones facilitate multichannel or 2-D-devices to increase their throughput and processing gain. We discuss general backgrounds of the guided wave AO devices, especially in the case of the collinear wave propagations. Some applications similar to the multichannel collinear AO Bragg cell on LiNbO for 2-D-beam scanning, AO spectrum analysis, 2-D- Fourier signal processing, frequency multiplexing/demultiplexing, and digital vector-matrix multiplication are presented.
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