Two-dimensional planar lightwave circuit integrated spatial filter array and method of use thereof
View Patent ↗A large coherent two-dimensional (2D) spatial filter array (SFA), 30 by 30 or larger, is produced by coupling a 2D planar lightwave circuit (PLC) array with a pair of lenslet arrays at the input and output side. The 2D PLC array is produced by stacking a plurality of chips, each chip with a plural number of straight PLC waveguides. A pupil array is coated onto the focal plane of the lenslet array. The PLC waveguides are produced by deposition of a plural number of silica layers on the silicon wafer, followed by photolithography and reactive ion etching (RIE) processes. A plural number of mode filters are included in the silica-on-silicon waveguide such that the PLC waveguide is transparent to the fundamental mode but higher order modes are attenuated by 40 dB or more.
1. An optical spatial filter array comprising a two dimensional planar lightwave circuit array, a first and a second microlens arrays, said planar light waves circuit array being coupled to said first and second microlens arrays at an inlet and outlet respectively, said planar lightwave circuit array comprising a plurality of vertically stacked silicon wafer chips, each of said chips having a plurality of straight planar lightwave circuit waveguides.
2. The optical spatial filter array of claim 1 wherein the planar lightwave circuit array has hexagonal grid geometry.
3. The optional spatial filters array of claim 1 wherein the two-dimensional planar lightwave circuit maintains a spatial and temporal coherency of the transported light.
4. A method of assembling an optical spatial filters array comprising the steps of:
1) Preparing a plurality of chips from a silicon wafer;
2) Forming a plurality of straight planar lightwave circuit waveguides on each said chip to form a waveguide array;
3) Stacking a plurality of said chips and
4) Coupling a lenslet array at each of the inlet and the outlet of said waveguide array.
5. The method of claim 4 wherein said waveguide array comprises at least a 30 by 30 array.