Transition between Kerr comb and stimulated Raman comb in a silica whispering gallery mode microcavity

Abstract

We theoretically and experimentally investigated the transition between modulation instability and Raman gain in a small silica microcavity with a large free-spectral range (FSR), which reveals that we can selectively switch from a four-wave mixing dominant state to a stimulated Raman scattering dominant state. Both the theoretical analysis and the experiment show that a Ramandominant region is present between transitions of Kerr combs with different free-spectral range spacings. We can obtain a stable Kerr comb and a stable Raman state selectively by changing the driving power, coupling between the cavity and the waveguide, and laser detuning. Such a controllable transition is achieved thanks to the presence of gain competition between modulation instability and Raman gain in silica whispering gallery mode microcavities.

Controllable Kerr and Raman-Kerr frequency combs in functionalized microsphere resonators

“…SRS in the silica microresonator is the phenomenon that can generate the Stokes wavelength (λ stokes ) which is about 13 THz away from the pump wavelength [42]. Therefore, the comb span can be broadened by combining with SRS [38,[43][44][45]. Here, we also realize the Raman-Kerr frequency comb with a wider span compared with the Kerr frequency comb.…”

Emerging material systems for integrated optical Kerr frequency combs

“…Given the complexity of this optimization problem, the initial research efforts into microcavity-based frequency combs chose to pursue non-integrated device designs. [4,39,60,176,207,269,[317][318][319][320][321][322][323][324][325][326][327][328] This approach removed restrictions related with onchip integration and nanofabrication compatibility during these investigations. However, to translate from the lab environment, researchers were motivated to expand beyond the conventional integrated photonics toolbox and to explore alternative material systems and integration strategies.…”

Nonlinear nanophotonic devices in the ultraviolet to visible wavelength range

“…Initial work investigating nonlinear phenomena was in the near-IR and focused on leveraging the ultra-high-Q factors possible in the whispering gallery mode cavities, particularly in silica and fluoride devices [207]. Despite the low nonlinear coefficients, Stokes and Anti-Stokes behavior [208][209][210] as well as four wave mixing [21,85,88,99,[211][212][213] were demonstrated. More recent efforts which are the focus of this section are investigating new material platforms to improve the nonlinear coefficient of the material and to open the door to new wavelength ranges.…”