Abstract: A polarization independent acousto-optic tunable filter (PIAOTF) used for multiwavelength switching and routing in wavelength division multiplexing (WDM) networks. In the PIAOTF an incident unpolarized light beam is divided to propagate and to be diffracted along two polarization division branches. By using polarization converters and equal optical paths for the two polarization division channels, a PIAOTF is created which minimizes polarization dependent loss and polarization mode dispersion. Furthermore, a preferred embodiment of the AOTF using an elongated acousto-optic interaction medium is described that provides the additional advantages of narrow bandwidth, lower drive power and easier alignment.

Abstract: An acousto-optic tunable filter based on isotropic acousto-optic diffraction using phased array transducers. The isotropic AOTF provides the advantages of narrow optical passband, low acoustic frequencies, and insensitivity to the input optical polarization. Preferred embodiments of the isotropic AOTFs are described for optimized spectral resolution and diffraction efficiency.

Abstract: An acousto-optic modulator utilizing light diffraction by phased acoustic waves in a birefringent crystal. The wavevector of the resultant acoustic wave is selected so that the tangents to the loci of the wavevectors of the incident and diffracted light are parallel. This provides a large acceptance angle for the acousto-optic modulator. By simultaneously choosing the acoustic wavevector to be tangential to the locus of the diffracted light wavevector, the acousto-optic modulator also achieves increased modulation bandwidth.