Tunable silicon based optical router
AssigneeAT&T Corp.
InventorJulian Stone
Life of this patent
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Abstract
An apparatus is provided that allows the tunability of a waveguide bench router with a silicon-based material. This is accomplished by adding a triangular shaped layer of hydrogenated amorphous silicon (a-Si:H) as an active region across the waveguide. By varying a current across the triangle, the refractive index of the layer will change causing a change to the delay of the signal going across the material. Thus eliminated are the need for Group III-V elements or Lithium Niobate as the tunable element, increasing the coupling efficiency and decreasing cost.
Claims12
A tunable router for providing an output signal of multiplexed wavelengths, comprising:
- a plurality of waveguides carrying an input signal having predetermined wavelengths;
- a silicon-based layer defining said plurality of waveguides comprising a width which varies along said silicon-based layer length and has an input side and an output side;
- and
- means for providing a change in refractive index of a trapezoidal active region of said silicon-based layer to thereby cause a delay shift of said input signal on at least one of said plurality of waveguides;
- wherein the degree of delay of said input signal is dependent upon said width of said active region between respective said input side and said output side of said silicon-based layer.
A wavelength tunable optical router comprising:
- a silicon-based substrate;
- an input optical free space region;
- an output optical free space region;
- a trapezoidal silicon-based active region optically coupled between said input optical free space region and output optical free space region by unequal length waveguides;
- and
- means for varying the refractive index of said active region to delay a transmission of said optical router.
A method for tuning a silicon-based router wherein the delay of the output signal can be varied, comprising the steps of:
- optically coupling a trapezoidal active region to an optical input;
- transmitting said signal across said active region having a defined width which varies along its length;
- injecting current into said active region tuning said silicon-based router;
- and
- optically coupling said active region to an optical input.
Dependencies are inferred from the claim text.