Optical interleaver

An optical multiplexer comprising:

• a) at least two input ports, each input port configured to receive optical signals from one or more optical fibers;
• b) at least one output port configured to transmit optical signals to one or more optical fiber;
• c) a first birefringent element optically coupled to the at least two input ports and the at least one output port, wherein the first birefringent element is configured to separate an optical signal from each of the input ports into an ordinary ray and an extraordinary ray;
• d) a first polarization rotator element optically coupled to the first birefringent element, wherein the first polarization rotator element is configured to rotate the polarizations of the ordinary and extraordinary rays in opposite directions;
• e) a second polarization rotator element optically coupled to the first polarization rotator element, wherein the second polarization rotator element is configured to rotate a polarization of a forward beam in a first sense and a polarization of a reverse beam in a second sense that is the same as the first sense;
• f) a wavelength filter optically coupled to the second polarization rotator element;
• g) a second birefringent element optically coupled to the wavelength filter;
• h) a third polarization rotator element optically coupled to the second birefringent element, wherein the third polarization rotator element is configured to rotate the polarizations of the forward and reverse beams in a sense opposite that of the second polarization rotator element;
• and
• i) a reflector optically coupled to the third polarization rotator element, wherein the reflector is configured to reflect an optical signal that travels from the at least two input ports through elements c)-h) back through elements c)-h) in reverse order to the at least one output port.

An optical de-multiplexer comprising:

• a) at least one input port configured to transmit optical signals;
• b) at least two output ports configured to transmit optical signals;
• c) a first birefringent element optically coupled to the at least one input port and the at least two output ports, wherein the first birefringent element is configured to separate an optical signal from each of the input ports into an ordinary ray and an extraordinary ray;
• d) a first polarization rotator element optically coupled to the first birefringence element, wherein the first polarization rotator element is configured to rotate the polarizations of the ordinary and extraordinary rays in opposite directions;
• e) a second polarization rotator element optically coupled to the first polarization rotator element, wherein the second polarization rotator element is configured to rotate a polarization of a forward beam in a first direction and a polarization of a reverse beam in a second direction that is opposite the first direction;
• f) a wavelength filter optically coupled to the second polarization rotator element;
• g) a second birefringent element optically coupled to the wavelength filter;
• h) a third polarization rotator element optically coupled to the second birefringent element, wherein the third polarization rotator element is configured to rotate the polarizations of the forward and reverse beams in a sense the same as that of the second polarization rotator element;
• and
• i) a reflector optically coupled to the third polarization rotator element, wherein the reflector is configured to reflect an optical signal that travels from the input port through elements c)-h) back through elements c)-h) in reverse order to at least one of the at least two output ports.