![]() ![]() In this communication, we aim at using this stochastic approach in order to characterize the coherence of the combs in the optical domain. One approach to understanding the effect of these fluctuations is to introduce Langevin noise terms leading to stochastic differential equations. However, the mechanism by which these noises affect the fluctuations, and further the phase noise of the combs, remains unclear. Researchers have studied various noises in the resonator theoretically and experimentally 13, 14, 15. Compared with other frequency comb generation systems, Kerr comb generators are simpler and more compact because of the small mode volume, high photon density, and long photon lifetime, but these advantages may introduce more noise. Most of these applications are based on the exceptional coherence of the combs, which is ultimately limited by noise-driven fluctuations. Kerr optical frequency combs have been found in numerous applications such as coherent optical communications 8, spectroscopy 9, sensing 10, 11, and ultra-pure microwave generation 12. From a theoretical viewpoint, Kerr combs have been studied extensively and their deterministic characteristics are nowadays well understood 5, 6, 7. Such phase-locking leads to the formation of well-defined patterns in the spatiotemporal domain, which can be extended (such as roll patterns), or localized (bright or dark solitons). In this latter case, the comb lines exhibit strong phase correlation in the spectral domain. A key characteristic of these combs is that there is a threshold pump power below which this four-wave mixing process is spontaneous, and above which it is stimulated. When the bulk medium of the cavity features a Kerr nonlinearity, the pump photons can be frequency-converted via four-wave mixing and populate adjacent cavity eigenmodes 3, 4. Kerr optical frequency combs are sets of discrete and equidistant spectral lines that can be generated using a high- Q monolithic resonator pumped with a resonant laser 1, 2. The theoretical results are found to be in excellent agreement with numerical simulations. In this latter case, our analysis indicates that the low-frequency part of the spectra is dominated by pattern drift while the high-frequency part is dominated by pattern deformation. ![]() Moreover, this study permits to determine the phase noise spectra of the microwaves generated via comb photodetection. This stochastic model allows us to characterize the noise-induced broadening of the spectral lines. In this communication, we theoretically investigate a model where Gaussian white noise is added to the coupled-mode equations governing the comb dynamics. For this reason, it is of high importance to understand the influence of random noise on the comb dynamics. Most of these applications are related to the metrological performance of Kerr combs, which is ultimately limited by their noise-driven fluctuations. Kerr optical frequency combs are expected to play a major role in photonic technology, with applications related to spectroscopy, sensing, aerospace, and communication engineering. ![]()
0 Comments
Leave a Reply. |