| Popis: |
Wavelength routing crossconnects are considered the core of WDM optical networks. They consist of optical switches independently rearrangeable for each wavelength channel and for any input- output configuration so that any path can be chosen almost arbitrarily by the network users. In general, the implementation of the wavelength routing function requires complex switch arrays. Very simple wavelength-selective crossconnects can be realized by using acousto-optic switches (AOS), because of their unique ability of processing several optical signals simultaneously and their low driving power consumption, less than 10 mW/channel. AOS's can be considered a particular evolution of acousto-optical tunable filters, whose integrated optic version on lithium niobate has been developed in several research institutions around the world in the past decade. This paper reviews the last accomplishments of AOS's, whose specifications are directly tied with optical network requirements, the foremost challenge being a strong suppression of crosstalk. Dilated AOS's can reduce interport crosstalk to below -30 dB and apodization of acousto-optic interaction can reduce interchannel crosstalk to below -15 dB during multiwavelength operation. |
