Silicon-based tunable single passband optical filter
First Claim
1. An apparatus, comprising:
- a semiconductor substrate;
a waveguide disposed in the semiconductor substrate, the waveguide having a core;
a first reflector and a second reflector disposed in the waveguide defining a resonator region between the first and second reflector, the first and second reflectors including a plurality of regions formed in the core of a material having a refractive index different from that of the core, wherein any resonant wavelengths of an optical signal propagated in the waveguide to the first and second reflectors propagates through the first and second reflectors with substantially no loss.
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Abstract
A tunable optical filter includes a tunable Fabry-Perot (FP) filter, two tunable waveguide Bragg gratings (WBGs) and a 2×2 3-dB coupler. In one embodiment, the WBGs are implemented in a silicon substrate using polysilicon filled trenches. The FP filter is implemented with two silicon nitride trench WBGs with a gap region between them. The FP filter and the WBGs are respectively tuned to transmit and reflect a selected wavelength. A broadband optical signal is propagated into a first port of the coupler. The coupler propagates half of the beam to one WBG and the other half to the other WBG. The WBGs reflect these portions back to the coupler, which then propagates the reflected portions to the FP filter.
102 Citations
30 Claims
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1. An apparatus, comprising:
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a semiconductor substrate;
a waveguide disposed in the semiconductor substrate, the waveguide having a core;
a first reflector and a second reflector disposed in the waveguide defining a resonator region between the first and second reflector, the first and second reflectors including a plurality of regions formed in the core of a material having a refractive index different from that of the core, wherein any resonant wavelengths of an optical signal propagated in the waveguide to the first and second reflectors propagates through the first and second reflectors with substantially no loss. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An integrated circuit Fabry-Perot (FP) filter, comprising:
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a semiconductor layer having a first region; and
a first reflector and a second reflector formed in the semiconductor layer at opposite ends of the first region, the first and second reflectors including trenches formed in the semiconductor layer and filled with a material having a refractive index different from that of the semiconductor layer. - View Dependent Claims (10, 11)
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12. An integrated circuit interferometer, comprising:
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a first waveguide formed in a semiconductor substrate;
a first grating formed in the semiconductor substrate;
a second grating formed in the semiconductor substrate; and
a coupler having a first port, a second port and a third port, the first, second and third ports formed in the semiconductor substrate, wherein the first, second and third ports are operatively coupled to the first waveguide, the first grating and the second grating, respectively, the coupler to cause first and second portions of an optical signal propagated to the coupler via the first waveguide to propagate to the first and second gratings, respectively. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A wavelength division multiplexed (WDM) system comprising:
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an optical signal source; and
a tunable optical filter to receive an optical signal from the optical signal source, the optical filter comprising;
a coupler disposed on a semiconductor substrate, the coupler having a first port, a second port, a third port and a fourth port, the coupler to receive the optical signal at the first port and propagate first and second portions of the optical signal to the second and third ports, respectively, the first and second portions having substantially equal power, a first tunable grating disposed on the semiconductor substrate to receive the first portion from the second port of the coupler and reflect a third portion of the first portion having a selected wavelength back to the coupler, a second tunable grating disposed on the semiconductor substrate to receive the second portion from the third port of the coupler and reflect a fourth portion of the second portion having the selected wavelength back to the coupler, and a tunable Fabry-Perot filter disposed on the semiconductor substrate to receive reflected signals from the fourth port of the coupler, the Fabry-Perot filter having a resonant wavelength equal to the selected wavelength. - View Dependent Claims (19, 20, 21, 22)
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23. A method of fabricating a Fabry-Perot filter, comprising:
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forming a planar waveguide in a semiconductor substrate having a core layer;
forming a pair of reflectors in the planar waveguide with a resonant region between the pair of reflectors. - View Dependent Claims (24, 25, 26)
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27. A method, comprising:
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propagating a multiple wavelength optical signal into a waveguide formed in a semiconductor substrate;
splitting the optical signal into first and second substantially equal portions to respectively propagate in second and third planar waveguides formed in the semiconductor substrate;
reflecting a selected wavelength of the first portion to propagate in the second planar waveguide and the selected wavelength of the second portion to propagate in the propagate in the third planar waveguide;
combining the reflected wavelengths from the first and second portions to propagate in a fourth planar waveguide formed in the semiconductor substrate; and
filtering the combined reflected wavelengths to transmit the selected wavelength. - View Dependent Claims (28, 29, 30)
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Specification