Temporal cavity solitons and frequency combs via quantum interference

Temporal cavity solitons in ring microresonators provide broad and controllable generation of frequency combs with applications in frequency standards and precise atomic clocks. Three-level media in the Λ configuration inside microresonators displaying electromagnetically induced transparency can be used for the generation of temporal cavity solitons and frequency combs in the presence of anomalous dispersion and two external driving fields close to resonance. Here domain walls separating regions of two dark states due to quantum interference correspond to realizations of stimulated Raman adiabatic passage without input pulses. With no need of modulational instabilities, bright temporal cavity solitons and frequency combs are formed when these domain walls lock with each other. Wide stability ranges, close to resonance operation, and the optimal shape of the cavity solitons due to three-level quantum interference can make them preferable to those in two-level media.