Packaged cryogenic photon pair source using an effective packaging methodology for cryogenic integrated optics

A cryogenic packaging methodology that is widely applicable to packaging any integrated photonics circuit for operation at both room temperature and cryogenic temperature is reported. The method requires only equipment and techniques available in any integrated optics lab and works on standard integrated photonic chips. Our methodology is then used to enable the measurement of a single photon pair source based on a silicon ring resonator at cryogenic temperatures. When operating at 5.9 K, this source is measured to have a peak pair generation rate that is 183 times greater than that at room temperature in the CL-band.