Alignment-tolerant interfacing of a photonic integrated circuit using back side etched silicon microlenses

Directly interfacing a photonic integrated circuit allows at best an alignment tolerance of a few micrometer due to the small dimensions of optical (coupling) features on chip, but when using microlenses integrated on the substrate-side, alignment tolerances for interfacing the chips can greatly be relaxed. This is demonstrated on a 750 μm thick chip with standard grating couplers (operation wavelength around 1550 nm). Low roughness silicon microlenses were realized by transferring reflowed photoresist into the silicon substrate using reactive ion etching. The microlens allows interfacing the chip from the backside with an expanded beam, drastically increasing lateral alignment tolerances. A 1 dB alignment tolerance of ±8 μm and ±11 μm (along and perpendicular to the grating coupler direction, respectively) was experimentally found when a 40 μm mode field diameter beam was used at the input.

ISBN:9781510624887

Jaar van publicatie:2019

BOF-keylabel:ja

IOF-keylabel:ja

Toegankelijkheid:Open