Wavelength selective optical add/drop multiplexer and method of manufacture

A multi-wavelength optical multiplexer comprising:

• a substrate including a top surface and a bottom surface, and coupling control circuitry adapted to provide a plurality of waveguide coupling signals;
• a plurality of waveguides disposed on the top surface of the substrate, each waveguide separated from the remaining waveguides, and adapted to transmit the plurality of wavelengths of light;
• and
• a plurality of switchable wavelength selective optical couplers coupled to the top surface of the substrate and adapted to resonate at a subset of resonant wavelengths of the plurality of wavelengths of light, each switchable wavelength selective optical coupler including;
• a resonator including a dielectric member which extends parallel to the top surface of the substrate and overlaps, without contacting, at least two of the plurality of waveguides, the dielectric member including an upper surface and a lower surface;
• and
• a bridge coupled to the resonator and electrically coupled to the coupling control circuitry, the bridge adapted to deform and translate the resonator between a waveguide decoupled position and a waveguide coupled position responsive to one of the plurality of waveguide coupling signals;
• whereby the resonator is optically coupled to the at least two of the plurality of waveguides in the waveguide coupled position.

A method of manufacturing a wavelength selective waveguide coupling device which includes a substrate;

• a primary waveguide transmitting a plurality of optical signals having a plurality of wavelengths;
• a secondary waveguide;
• a resonator which extends over the primary waveguide and the secondary waveguide;
• and a pedestal to couple the resonator to the substrate, the method comprising the steps of:
• a) planarizing the substrate;
• b) depositing a passivation layer on the substrate, the passivation layer including an electrically insulating and optically transmissive material characterized by a first index of refraction;
• c) depositing a waveguide layer on the passivation layer, the waveguide layer including an optically transmissive material characterized by a second index of refraction and a waveguide thickness, the second index of refraction being greater than the first index of refraction;
• d) defining and etching the waveguide layer to form the primary waveguide and the secondary waveguide;
• e) depositing a release layer over the passivation layer, the primary waveguide, and the secondary waveguide, the release layer having a first thickness on top of the passivation layer, the first thickness being greater than the waveguide thickness;
• f) planarizing the release layer, the planarized release layer having a second thickness on top of the passivation layer, the second thickness being greater than the waveguide thickness;
• g) depositing a resonator layer on the release layer, the resonator layer including an optically transmissive material with a third index of refraction, the third index of refraction being substantially the same as the second index of refraction;
• h) defining and etching the resonator layer to form the resonator;
• and
• i) etching the release layer to form the pedestal and to uncover the primary waveguide and the secondary waveguide.

A method of manufacturing a wavelength selective waveguide coupling device which includes a CMOS control circuit substrate having a top surface;

• a primary waveguide;
• a secondary waveguide;
• a resonator which extends over the primary waveguide and the secondary waveguide;
• a heating means to tune a resonant wavelength of the resonator;
• and a coupling means to couple the resonator to the substrate, the method comprising the steps of:
• a) planarizing the top surface of the CMOS control circuit substrate;
• b) depositing a passivation layer on the top surface of the CMOS control circuit substrate, the passivation layer including an electrically insulating and optically transmissive material characterized by a first index of refraction;
• c) depositing a waveguide layer on the passivation layer, the waveguide layer including an optically transmissive material characterized by a second index of refraction and a waveguide thickness, the second index of refraction being greater than the first index of refraction;
• d) defining and etching the waveguide layer to form the primary waveguide and the secondary waveguide;
• e) defining and etching the passivation layer to form a first plurality of vias exposing a plurality of electrical contacts on the top surface of the CMOS control circuit substrate;
• f) depositing a first plurality of metal plugs in the first plurality of vias, the first plurality of metal plugs electrically coupled to the electrical contacts;
• g) depositing a release layer over the passivation layer, the first plurality of metal plugs, the primary waveguide, and the secondary waveguide, the release layer having a first thickness on top of the passivation layer, the first thickness being greater than the waveguide thickness;
• h) defining and etching the release layer to form a second plurality of vias exposing the first plurality of metal plugs;
• i) depositing a second plurality of metal plugs in the second plurality of vias, the second plurality of metal plugs electrically coupled to the first plurality of metal plugs and forming at least a portion of the coupling means;
• j) planarizing the release layer and the second plurality of metal plugs, the planarized release layer having a second thickness on top of the passivation layer, the second thickness being greater than the waveguide thickness;
• k) depositing a resonator layer on the release layer and the second plurality of metal plugs, the resonator layer including an optically transmissive material characterized by a third index of refraction, the third index of refraction being substantially the same as the second index of refraction;
• l) depositing a resonator cover layer on the resonator layer, the resonator cover layer including an electrically insulating and optically transmissive material characterized by a fourth index of refraction, the fourth index of refraction being less than the third index of refraction;
• m) defining and etching the resonator cover layer to form a resonator cover and a third plurality of vias;
• n) defining and etching the resonator layer to form the resonator and a fourth plurality of vias extending from the third plurality of vias to the second plurality of metal plugs;
• o) depositing a third plurality of metal plugs in the fourth plurality of vias and the third plurality of vias, the third plurality of metal plugs being electrically coupled to the second plurality of metal plugs;
• p) depositing a heating layer on the resonator cover, the heating layer including an electrically conductive material and being electrically coupled to the third plurality of metal plugs;
• q) defining and etching the heating layer to form the heating means;
• and
• r) etching the release layer to uncover the primary waveguide and the secondary waveguide and substantially remove the release layer.

A method of manufacturing a wavelength selective waveguide coupling device which includes a CMOS control circuit substrate having a top surface;

• a primary waveguide;
• a secondary waveguide;
• a resonator which extends over the primary waveguide and the secondary waveguide;
• a heating means to tune a resonant wavelength of the resonator;
• a coupling means to couple the resonator to the substrate;
• and at least one deformable bridge adapted to translate the resonator between a coupled position and a decoupled position, the method comprising the steps of:
• a) depositing a CMOS cap layer on the top surface of the CMOS control circuit substrate, the CMOS cap layer including an electrically insulating material;
• b) depositing a passivation layer on the top surface of the CMOS cap layer, the passivation layer including an optically transmissive material exhibiting a first index of refraction;
• c) defining and etching the passivation layer to form a first plurality of vias and openings to allow release of the at least one deformable bridge;
• d) defining and etching the CMOS cap layer to form a second plurality of vias extending from the first plurality of vias to a plurality of electrical contacts on the top surface of the CMOS control circuit substrate;
• e) depositing a first plurality of metal plugs in the second plurality of vias and the first plurality of vias, the first plurality of metal plugs electrically coupled to the electrical contacts;
• f) depositing a first release layer to fill in the openings in the passivation layer;
• g) planarizing the passivation layer, the release layer, and the first plurality of metal plugs;
• h) depositing a waveguide and bridge layer on the passivation layer, the release layer, and the first plurality of metal plugs, the waveguide and bridge layer including an optically transmissive material characterized by a second index of refraction and a waveguide thickness, the second index of refraction being greater than the first index of refraction;
• i) defining and etching the waveguide layer to form the primary waveguide, the secondary waveguide, and the at least one deformable bridge, the at least one deformable bridge including a third plurality of vias exposing the first plurality of metal plugs;
• j) depositing a second plurality of metal plugs in the third plurality of vias, the second plurality of metal plugs electrically coupled to the first plurality of metal plugs;
• k) depositing a plurality of bridge electrodes on the at least one deformable bridge, the plurality of bridge electrodes including an electrically conductive material and being electrically coupled to the second plurality of metal plugs;
• l) depositing a second release layer over the passivation layer, the first release layer, the primary waveguide, the secondary waveguide, the at least one deformable bridge and the plurality of bridge electrodes, the second release layer having a first thickness on top of the passivation layer, the first thickness being greater than the waveguide thickness;
• m) defining and etching the release layer to form a forth plurality of vias exposing a contact portion of the plurality of bridge electrodes;
• n) depositing a third plurality of metal plugs in the forth plurality of vias, the third plurality of metal plugs electrically coupled to the plurality of bridge electrodes and forming at least a portion of the coupling means;
• o) planarizing the second release layer and the third plurality of metal plugs, the planarized second release layer having a second thickness on top of the passivation layer, the second thickness being greater than the waveguide thickness;
• p) depositing a resonator layer on the second release layer and the third plurality of metal plugs, the resonator layer including an optically transmissive material characterized by a third index of refraction, the third index of refraction being substantially the same as the second index of refraction;
• q) depositing a resonator cover layer on the resonator layer, the resonator cover layer including an electrically insulating and optically transmissive material characterized by a fourth index of refraction, the fourth index of refraction being less than the third index of refraction;
• r) defining and etching the resonator cover layer to form a resonator cover and a fifth plurality of vias;
• s) defining and etching the resonator layer to form the resonator and a sixth plurality of vias extending from the fifth plurality of vias to the third plurality of metal plugs;
• t) depositing a fourth plurality of metal plugs in the sixth plurality of vias and the fourth plurality of vias, the fourth plurality of metal plugs electrically coupled to the third plurality of metal plugs;
• u) depositing a heating layer on the resonator cover, the heating layer including an electrically conductive material and being electrically coupled to the fourth plurality of metal plugs;
• v) defining and etching the heating layer to form the heating means;
• and
• w) etching the second release layer and the first release layer to uncover the primary waveguide and the secondary waveguide, release the at least one deformable bridge, and substantially remove the release layer.

A method encoding information as a narrow wavelength band digital optical signal using an integrated optical component including an optical source optically coupled to a first waveguide;

• a second waveguide;
• a resonator sized to resonate in a narrow resonator wavelength band;
• a resonator translating means adapted to translate the resonator between a coupled position in which the resonator optically couples the first waveguide to the second waveguide and a decoupled position in which the resonator does not optically couples the first waveguide to the second waveguide;
• and control circuitry electrically coupled to the resonator coupling means and adapted to form a digital electric signal in response to the information, the method comprising the steps of:
• a) operating the optical source to provide optical radiation to the first waveguide, the optical radiation exhibiting a substantially constant amplitude and a source wavelength band which includes the narrow resonator wavelength band;
• b) providing the information to the control circuitry to form the digital electric signal;
• c) providing the digital electric signal to the resonator translating means to translate the resonator between the coupled position and the decoupled position;
• and
• d) transferring optical radiation in the narrow resonator wavelength band from the first waveguide to the second waveguide when the resonator is in the coupled position and not transferring optical radiation from the first waveguide to the second waveguide when the resonator is in the decoupled position to form the narrow wavelength band digital optical signal in the second waveguide.