Patent ID: 6370286
Filing Date: 2002-04-09
Classification: G02B

Abstract:
A tunable optical channel routing device, comprising:an input for a plurality of optical channels having a frequency period; a first polarization beam displacer having a thickness, d, in an optical path of the input channels for separating and transmitting an output comprising orthogonal (s and p) polarization states of the input; a birefringent crystal in the first polarization beam displacer output optical path having a thickness L and a c-axis oriented at 45Â° with respect to the s and p polarization states such that the crystal propagates an output comprising at least one of an ordinary beam and an extraordinary beam; a second polarization beam displacer having a thickness, d, in the crystal output optical path for separating and transmitting an output comprising orthogonal (s and p) polarization states of the second polarization beam displacer output, one of which is a second group of output channels; an optical path length compensator located in an optical path of one of the s and p polarization states output from the second polarization beam displacer; a third polarization beam displacer having a thickness, 2 d, in the second polarization beam displacer output optical path of one of the s and p polarizations for combining and transmitting a first group of output channels, wherein each channel of a first group of output channels has a center frequency and the first group of output channels has a frequency period that is different from the frequency period of the input channels, and wherein each channel of a second group of output channels has a center frequency and the second group of output channels has a frequency period different from the frequency period of the input channels and is interleaved with the first group; further wherein the device has a contrast ratio &gE;20 dB over a spectral band from about 1520 nm to 1570 nm.