Mode multiplexer/demultiplexer using metamaterials for optical fiber communications
Systems, devices, and techniques for performing wavelength division multiplexing or demultiplexing using one or more metamaterials in an optical communications systems are described. An optical device may be configured to shift one or more phase profiles of an optical signal using one or more stages of metamaterials to multiplex or demultiplex wavelengths of optical signals. The optical device may be an example of a stacked design with two or more stages of metamaterials stacked on top of one another. The optical device may be an example of a folded design that reflects optical signals between different stages of metamaterials.
1 . An apparatus, comprising:
a plurality of input optical fibers, each configured to propagate one of a plurality of input optical signals in a corresponding input spatial mode;
an output optical fiber configured to propagate an output optical signal in a selected output spatial mode; and
an optical multiplexer coupled between the plurality of input optical fibers and the output optical fiber, the optical multiplexer comprising:
a substrate that is optically transmissive;
a first reflector in contact with a first side of the substrate, the first reflector including at least one input aperture configured to accept the input optical signal from the plurality of input optical fibers and at least one output aperture configured to output the output optical signal to the output optical fiber; and
a multi-stage metamaterial in contact with a second side of the substrate opposite the first side,
the multi-stage metamaterial including a plurality of structures protruding from the substrate, the plurality of structures arranged in a pattern configured to impart a spatially dependent phase delay to the plurality of input optical signals, the spatially dependent phase delay based on the corresponding input spatial mode and the output spatial mode.
2 . The apparatus of claim 1 , further comprising a second reflector configured to reflect the plurality of input optical signals, the substrate positioned between the first reflector and the second reflector.
3 . The apparatus of claim 2 , further comprising:
cladding positioned between the multi-stage metamaterial and the second reflector.
4 . The apparatus of claim 2 , wherein the substrate, the first reflector, the second reflector, and the multi-stage metamaterial form a Fabry-Perot cavity configured to generate one or more resonant reflections of the plurality of input optical signals.
5 . The apparatus of claim 1 , wherein
the plurality of structures include a same cross sectional shape to shift a phase profile of an optical signal.
6 . The apparatus of claim 5 , wherein the plurality of structures include different cross sectional areas.
7 . The apparatus of claim 5 , wherein the plurality of structures include different heights.