A linear optical coupler for cryogenic detectors

We present an improved version of a linear low-noise optical coupler having differential input and capable of driving a twisted cable to long distances, avoiding ground loops and electromagnetic interference. Owing to device optimization, this circuit version is able to be fast. Its frequency bandwidth is about 900 kHz, more than ten times larger than our previous implementation. The optical coupler presented is therefore suitable to be used with most of the applications with cryogenic detectors.