On-chip structure for fiber array alignment by assisting edge coupler index-matching epoxy/oil filling
Embodiments of the present disclosure may comprise a system for filling undercuts with an index-matching liquid on a wafer, the system comprising a plurality of edge couplers, each comprising an undercut and a waveguide. Embodiments may also comprise ribs that suspend the waveguide over the undercut. Embodiments may also comprise one or more main buckets and one or more monitor buckets. Embodiments may also comprise a duct that couples together the plurality of edge couplers, the one or more main buckets, and the one or more monitor buckets.
1 . A system comprising:
a plurality of edge couplers, each comprising an undercut formed beneath a waveguide, wherein ribs suspend the waveguide over the undercut;
one or more main buckets configured to receive an index-matching liquid;
one or more monitor buckets; and
a duct that couples together the plurality of edge couplers, the one or more main buckets, and the one or more monitor buckets, wherein;
the duct fluidically interconnects the undercuts of the plurality of edge couplers with the one or more main buckets and the one or more monitor buckets to form a network of communicating vessels such that a hydrostatic pressure of the index-matching liquid equalizes across the plurality of edge couplers, and
the duct forms communicating vessels between the plurality of edge couplers, the one or more main buckets, and the one or more monitor buckets, such that the index-matching liquid introduced through the one or more main buckets is directed to flow through the duct to simultaneously fill the undercuts of the plurality of edge couplers and flow to the one or more monitor buckets, thereby assisting uniform filling and monitoring of the index-matching liquid across multiple edge couplers on a wafer.
2 . The system of claim 1 , wherein said index-matching liquid is an oil or an epoxy.
3 . The system of claim 1 , wherein said one or more main buckets comprise an opening to add said index-matching liquid into said system.
4 . The system of claim 3 , wherein said opening is the shape of a square with a side length of 0.5 millimeters.
5 . The system of claim 3 , wherein said opening is the shape of a circle with a diameter of 0.5 millimeters.
6 . The system of claim 3 , wherein said opening is suitable for said filling with said index-matching liquid by an automatic station.
7 . The system of claim 1 , wherein said one or more monitor bucket comprise an opening to monitor said filling process.
8 . The system of claim 1 , wherein a separation distance between at least one of said one or more monitor buckets and at least one of said one or more main buckets is greater than the separation distance between any one of said undercuts and any of said one or more main buckets.
9 . The system of claim 1 , wherein said plurality of undercuts, said one or more main buckets, and said one or more monitor buckets are formed on a same layer of said wafer.
10 . The system of claim 1 , wherein said plurality of undercuts, said one or more main buckets, and said one or more monitor buckets are of a same depth.
11 . The system of claim 1 , wherein said coupling by said duct forms communicating vessels from said plurality of edge couplers, said one or more main buckets, and said one or more monitor buckets.
12 . The system of claim 1 , wherein said filling of said undercuts with said index-matching liquid increases a mode field diameter at the facet of said waveguides.
13 . The system of claim 1 , wherein a mode field diameter at the facet of said waveguide is approximately 4 micrometers without said index-matching liquid.
14 . The system of claim 1 , wherein a mode field diameter at the facet of said waveguide is approximately 9 micrometers with said index-matching liquid.
15 . The system of claim 1 , wherein a photonic integrated circuit comprises said system.
16 . The system of claim 1 , wherein said wafer is a silicon photonics wafer.
17 . The system of claim 1 , wherein the duct comprises a continuous channel extending along a row of the plurality of edge couplers such that each undercut is fluidically coupled to adjacent undercuts.
18 . The system of claim 1 , wherein the one or more monitor buckets are positioned at distal ends of the duct relative to the one or more main buckets to indicate completion of filling.
19 . The system of claim 1 , wherein the duct is formed in a same lithographic layer as the undercuts to maintain uniform capillary flow characteristics.