Two-dimensional conformal optically-fed phased array and methods of manufacturing the same
This disclosure is directed to two-dimensional conformal optically-fed phased arrays and methods for manufacturing the same. The method includes providing a substrate, depositing a first cladding layer on the substrate, and depositing a core layer on the first cladding layer. The method further includes photolithographically patterning the core layer to provide a plurality of optical waveguide cores, and depositing a second cladding layer on the core layer to cover the plurality of optical waveguide cores to provide a plurality of optical waveguides. In addition, the method includes forming a plurality of antennas on the second cladding layer, each antenna of the plurality of antennas located near a termination of a corresponding optical waveguide of the plurality of optical waveguides, and providing a plurality of photodiodes on the second cladding layer, each photodiode of the plurality of photodiodes connected to a corresponding antenna.
1. A method of manufacturing an optical waveguide module, comprising:
providing a substrate;
depositing a first cladding layer on the substrate;
depositing a core layer on the first cladding layer;
photolithographically patterning the core layer to provide a plurality of optical waveguide cores;
depositing a second cladding layer on the plurality of optical waveguide cores to provide a plurality of optical waveguides;
patterning a plurality of openings extending through the first cladding layer, the core layer, and the second cladding layer;
providing a plurality of micro-bends, each micro-bend of the plurality of micro-bends provided in a corresponding opening of the plurality of openings;
forming a plurality of antennas on the second cladding layer, each antenna of the plurality of antennas located near a termination of a corresponding optical waveguide of the plurality of optical waveguides and a corresponding micro-bend of the plurality of micro-bends; and
providing a plurality of photodiodes on the second cladding layer, each photodiode of the plurality of photodiodes connected to a corresponding antenna of the plurality of antennas and located above a corresponding micro-bend of the plurality of micro-bends.
2. The method of claim 1 , further comprising:
integrating an input fiber array with the plurality of optical waveguides.
3. The method of claim 1 ,
wherein the first cladding layer includes silicon oxide, and
wherein the first cladding layer has a thickness less than 5 μm.
4. The method of claim 1 ,
wherein the core layer includes silicon nitride, and
wherein the core layer has a thickness less than 0.4 μm.
5. The method of claim 1 ,
wherein the second cladding layer includes silicon oxide, and
wherein the second cladding layer has a thickness of less than 6 μm.
6. The method of claim 1 , wherein the plurality of micro-bends include at least one of a microprism, a photoresist mirror, wet-etch silicon Si mirror, and an epitaxially-grown microprism.
7. The method of claim 1 ,
wherein each antenna of the plurality of antennas is a dipole antenna having a first radiating arm and a second radiating arm extending in a first direction, and having a length L in the first direction, and
wherein each photodiode of the plurality of photodiodes has an anode electrically connected to the first radiating arm of a corresponding dipole antenna with a first conductor, and a cathode electrically connected to the second radiating arm of the corresponding dipole antenna with a second conductor.
8. The method of claim 7 ,
wherein a length of the first conductor as measured from a first connection point of the first conductor to the anode to a second connection point of the first conductor to the first radiating arm is less than the length L of the dipole antenna, and
wherein a length of the second conductor as measured from a first connection point of the second conductor to the cathode to a second connection point of the second conductor to the second radiating arm is less than the length L of the dipole antenna.
9. The method of claim 8 , wherein a length of each of the first and second conductors is less than or equal to L/2.
10. An antenna array system, comprising:
a substrate;
a first cladding layer and a core layer on the substrate and forming a plurality of waveguide cores;
a second cladding layer covering the plurality of waveguide cores to provide a plurality of optical waveguides;
a plurality of antennas on the second cladding layer, each antenna of the plurality of antennas located near a termination of a corresponding optical waveguide of the plurality of optical waveguides;
a plurality of photodiodes on the second cladding layer, each photodiode of the plurality of photodiodes connected to a corresponding antenna of the plurality of antennas and configured to generate an RF current to drive the corresponding antenna; and
a plurality of micro-bends, each micro-bend of the plurality of micro-bends aligned with a corresponding photodiode of the plurality of photodiodes and configured to receive an optical signal from a corresponding optical waveguide among the plurality of optical waveguides and redirect the optical signal to the corresponding photodiode.
11. The antenna array system of claim 10 ,
wherein each antenna of the plurality of antennas is a dipole antenna having a first radiating arm and a second radiating arm extending in a first direction, and having a length L in the first direction, and
wherein each photodiode of the plurality of photodiodes has an anode electrically connected to the first radiating arm of a corresponding dipole antenna with a first conductor, and a cathode electrically connected to the second radiating arm of the corresponding dipole antenna with a second conductor.
12. The antenna array system of claim 11 ,
wherein a length of the first conductor as measured from a first connection point of the first conductor to the anode to a second connection point of the first conductor to the first radiating arm is less than the length L of the dipole antenna, and
wherein a length of the second conductor electrically as measured from a first connection point of the second conductor to the cathode to a second connection point of the second conductor to the second radiating arm is less than the length L of the dipole antenna.
13. The antenna array system of claim 12 , wherein a length of each of the first and second conductors is less than or equal to L/2.
14. The antenna array system of claim 11 , wherein adjacent radiating arms of adjacent first and second dipole antennas are electrically connected to each other.
15. The antenna array system of claim 11 , wherein adjacent radiating arms of adjacent dipole antennas are electrically coupled to each other by a capacitor.
16. An antenna array system, comprising:
a ground plane including a plurality of slots;
a first substrate on a first side of the ground plane, the first substrate including a plurality of antennas, each antenna of the plurality of antennas aligned with a corresponding slot of the plurality of slots;
a second substrate on a second side of the ground plane; and
an input array module on the second side of the ground plane and including an optical connector to connect to an optical fiber array,
wherein the second substrate includes a plurality of RF transmission lines, each RF transmission line extending from the input array module to a corresponding slot of the plurality of slots,
wherein the input array module is configured to receive optical signals from the optical fiber array, convert the received optical signals to RF signals, and output the RF signals to the plurality of RF transmission lines,
wherein each RF transmission line of the plurality of RF transmission lines is configured to receive at least one RF signal of the plurality of RF signals output by the input array module and transmit the RF signal to a corresponding antenna of the plurality of antennas.
17. The antenna array system of claim 16 , wherein the input array module includes a v-groove assembly.
18. The antenna array system of claim 16 ,
wherein each groove of the optical connector has an axis substantially parallel to a surface of the first substrate and the second substrate so that an optical axis of an optical fiber when placed in the groove is substantially parallel the surface of the first substrate or the second substrate.
19. The antenna array system of claim 16 , wherein the input array module comprises:
a module substrate; and
a plurality of photodiodes mounted on the module substrate,
wherein the optical connector comprising a plurality of grooves, each groove configured to hold a terminating end of a corresponding fiber of the optical fiber array, and
wherein each photodiode is positioned adjacent to a corresponding groove of the optical connector to be in optical communication with a corresponding optical fiber of the optical fiber array.
20. The antenna array system of claim 19 ,
wherein the module substrate comprises a plurality of reflectors on the module substrate, and
wherein each reflector is optically interposed between a corresponding groove and a corresponding photodiode to reflect an optical signal provided by a corresponding optical fiber when placed in the corresponding groove through a corresponding hole in the module substrate to impinge the corresponding photodiode.