We recently operated a polarization converter in lithium niobate waveguides down to a temperature of about 1K. The polarization converter can convert an input polarization into an orthogonal polarization controlled by a modulation voltage. The realized converter is our first active modulator in lithium niobate we have operated at cryogenic temperatures. The realization of active optical components at this temperature is an important step for us towards realizing an integrated optical platform in lithium niobate. We aim to realize various optical components at cryogenic temperatures in order to integrate the devices with detectors such as superconducting single photon detectors.
The paper is available at:
Frederik Thiele, Felix vom Bruch, Victor Quiring, Raimund Ricken, Harald Herrmann, Christof Eigner, Christine Silberhorn, and Tim J. Bartley, "Cryogenic electro-optic polarisation conversion in titanium in-diffused lithium niobate waveguides," Opt. Express 28, 28961-28968 (2020)