Soliton dual frequency combs in crystalline microresonators.

We present a novel compact dual-comb source based on a monolithic optical crystalline MgF₂ multi-resonator stack. The coherent soliton combs generated in the two microresonators of the stack with the repetition rate of 12.1 GHz and difference of 1.62 MHz provided after heterodyning a 300 MHz wide radio frequency comb. An analogous system can be used for dual-comb spectroscopy, coherent LIDAR applications, and massively parallel optical communications.