High-throughput manufacturing of photonic integrated circuit (PIC) waveguides using multiple exposures

A method of forming an optical interconnect between first and second photonic chips, comprising:

• attaching a polymer tape to the first and second photonic chips so that the polymer tape contacts a first waveguide of the first photonic chip and a second waveguide of the second photonic chip, wherein the polymer tape forms a freestanding optical interconnect bridging the first and second photonic chips;
• forming a plurality of cladding regions in the polymer tape using a first dosage of radiation that causes a reduction in a refractive index of the polymer tape such that a second region in the polymer tape between adjacent cladding regions defines a waveguide core that contacts the first waveguide of the first photonic chip and the second waveguide of the second photonic chips;
• forming an upper cladding region in the polymer tape by exposing at least the second region to a second dosage of radiation that is less than the first dosage of radiation;
• and
• heating the polymer tape to complete curing of the polymer tape and to further decrease the refractive index of the cladding regions while increasing the refractive index of the waveguide core.