Cryogenic optical packaging using photonic wire bonds

The widespread adaptation of systems relying on optically controlled quantum information will require reliable and efficient multi-channel fiber-to-chip connections that function at cryogenic temperatures. Here we demonstrate low loss (2 dB per channel) connections between a single mode fiber array and tapered silicon waveguides down to 5 K using polymer based photonic wire bonds (PWBs). A method is described for assembling the silicon chip and fiber array such that the PWB connections are robust to temperature cycling and cryostat bakeout. The threshold power handling capability of the PWBs is greater than 4 dBm, sufficient to demonstrate optical bistability in silicon microring resonators coupled to the waveguides at 5 K.