Direct 3D-printed ring-resonator photonic circuit on a dual core fiber tip for remote sensing applications.

On-chip optical sensors using ring- and disk-resonators have many potential sensing applications, yet robust and efficient fiber-to-chip coupling and the differing form factor between the two pose deployment challenges. To resolve this, we 3D-printed a ring-resonator onto the tip of a dual-core fiber and demonstrate its use as a remote temperature sensor. The fiber-tip optical circuit is fabricated using direct laser writing (DLW) with two-photon absorption photopolymer material IP-Dip, forming micrometer-scale waveguide cores having a refractive index of 1.