Potassium Tantalate-Niobate for Electro-Optically Driven Adiabatic Frequency Conversion

Many laser frequencies can be accessed by optical frequency conversion only, making the technology essential for a wide range of applications in, e.g., quantum optics and metrology. In most cases, nonlinear-optical effects are employed for changing the frequency of laser light. Here, high light intensities are needed and phase-matching must be observed. However, with adiabatic frequency conversion (AFC) we can work at the single-photon level and phase matching does not play a role. Here, the frequency of light is shifted by changing the optical length of an optical resonator. The frequency of the intracavity light follows the eigenfrequency changes, as long as they occur on a timescale smaller than the resonator's decay time [1], [2]. In a very convenient scheme, the eigenfrequency is varied by the linear or quadratic electro-optic effect. By using a high-quality bulk or on-chip lithium niobate (LN) microresonator, AFC in the range of 10 GHz was achieved [3], [4].