Patent ID: 6459831
Filing Date: 2002-10-01
Classification: G02B

Abstract:
A wavelength division multiplexer (WDM), comprising:a birefringent plate, wherein the birefringent plate separates a composite optical signal into a first sub-light and a second sub-light, wherein the first and second sub-lights have mutually orthogonal linear polarizations; a reciprocal optical rotator optically coupled to the birefringent plate, wherein the reciprocal optical rotator rotates a polarization plane of the first sub-light; and a diffraction grating optically coupled to the reciprocal optical rotator at a side opposite to the birefringent plate, wherein the diffraction grating spatially separates the first sub-light into a first signal and a third signal, and the second sub-light into a second signal and a fourth signal, wherein the first and third signals comprise a first wavelength, and the second and fourth signals comprise a second wavelength, wherein the diffraction grating reflects the first, second, third, and fourth signals to toward the reciprocal optical rotator and the birefringent plate, wherein the reciprocal optical rotator rotates a polarization plane of the first and second signals, wherein the birefringent plate combines the first and third signals, and combines the second and fourth signals.