Nonlinear wave mixing in optical microresonators new perospects for compact optical frequency combs with many promising applications. We demonstrate simultaneous generation of multiple frequency combs from a single optical microresonator and a single continuous-wave laser. Similar to space-division multiplexing, we generate several dissipative Kerr soliton states – circulating solitonic pulses driven by a continuous-wave laser – in different spatial (or polarization) modes of a MgF<sub>2</sub> microresonator. Up to three distinct combs are produced simultaneously, featuring excellent mutual coherence and substantial repetition rate differences, useful for fast acquisition and efficient rejection of soliton intermodulation products. This method could enable the deployment of dual- and triple-comb-based methods to applications where they remained impractical with current technology.
We experimentally demonstrate three-fold wavelength multicasting of a 64-quadrature-amplitude-modulation (QAM), 120-Gbit/s data channel using a microresonator Kerr frequency comb and nonlinear wave mixing. The multicasting is achieved with a data signal and four comb lines serving as the pump lasers in a periodically poled lithium niobate (PPLN) waveguide. Minimal extra phase noise from the pumps is introduced into the multicast copies due to the mutual coherence between the Kerr comb lines. All three multicast copies achieve a bit-error rate (BER) <= 3.5E-3, which is below the forward-error-correction threshold. Both the error vector magnitude (EVM) and BER performances show <0.5-dB optical signal-to-noise ratio (OSNR) penalty for the multicast copies compared to the original data signal.
Dissipative Kerr solitons (DKS) generated in optical microresonators have attracted significant attention over recent years in the areas of optical frequency metrology, spectroscopy and coherent communication. DKS allow for fully coherent, high repetition rate broadband optical frequency combs (soliton combs) and provide access to stable ultrashort pulses of tunable duration. The formation process and the dynamics of such dissipative solitons strongly depend on the interplay of high-order nonlinear and thermal properties of the microresonator, and in many aspects significantly deviate from the behavior of solitons in optical fibers. This talk will focus on the fundamental principles of DKS dynamics, and cover the range of various unique phenomena discovered in such systems.
Chip-scale frequency comb sources are key elements for a variety of applications, comprising massively parallel optical communications and high-precision optical metrology. In this talk, we give an overview on our recent progress in the area of integrated optical comb generators and of the associated applications. Our experiments cover modulator-based comb sources, injection locking of gain-switched laser diodes, quantum-dash mode-locked lasers, as well as Kerr comb sources based on cavity solitons. We evaluate and compare the performance of these devices as optical sources for massively parallel wavelength division multiplexing at multi-terabit/s data rates, and we report on comb-based approaches for high-precision distance metrology.