An acousto-optic modulator based bi-frequency interferometer for quantum technology

Abstract: We demonstrate a high performance AOM based bi-frequency interferometer, which can realize either beating or beating free interference for single photon level quantum state. Visibility and optical efficiency of the interferometer are (99.5 +- 0.2)% and (95 +- 1)%, respectively. The phase of the interferometer is actively stabilized by using dithering phase locking scheme, where the phase dithering is realized by directly driving the AOMs with specially designed electronic signal. We further demonstrate applications of the interferometer in quantum technology, including bi-frequency coherent combination, frequency tuning and optical switching. These result show the interferometer is a versatile device for multiple quantum technologies.