Patent ID: 6175432
Filing Date: 2001-01-16
Classification: G02B,G02F,H04J,H04Q

Abstract:
An optical device that separates an input signal into a first output signal having a first spectral band and a second output signal having a second spectral band, wherein the first and second spectral bands are substantially complementary, the device comprising:a first element that spatially separates the input signal into a first beam and a second beam that have orthogonal polarizations;a first polarization rotator that rotates the polarization of one of the first beam and the second beam to the polarization of the other of the first beam and the second beam;a first wavelength filter having a polarization dependent optical transmission function such that the first beam is decomposed into a third beam and a fourth beam and the second beam is decomposed into a fifth beam and a sixth beam, wherein the third beam and the fifth beam carry the first spectral band at a first polarization and the fourth beam and the sixth beam carry the second spectral band at a second polarization that is orthogonal to the first polarization;a second element that spatially separates the third and fourth beams and spatially separates the fifth and sixth beams;a second wavelength filter having a polarization dependent optical transmission function such that the first and second spectral bands are purified, and the polarization of one of the third beam and the fourth beam is rotated to the polarization of the other of the third beam and the fourth beam, and the polarization of one of the fifth beam and the sixth beam is rotated to the polarization of the other of the fifth beam and the sixth beam;a second polarization rotator that rotates the polarization of one of the third beam and the fifth beam to the polarization of the other of the third beam and the fifth beam, and rotates the polarization of one of the fourth beam and the sixth beam to the polarization of the other of the fourth beam and the sixth beam; anda third element that combines the third beam and fifth beam to form the first output signal and combines the fourth beam and the sixth beam to form the second output signal.