I. Introduction
Generating temporal-dissipative Kerr solitons (DKS) in the anomalous dispersion regime of high- microresonators is an attractive way to generate low-phase-noise, coherent Kerr frequency combs (‘microcomb’) with a broad spectral bandwidth [1]–[2]. Conventionally accessing a stable soliton region typically requires the pump laser to be red-detuned relative to the thermally and Kerr shifted cavity resonance, which results in sudden change to the intracavity power during DKS transition. Consequently, the cavitypump detuning increases due to the thermal instability and the pump exits the DKS stability region. One of the techniques to overcome this challenge is to use an auxiliary laser in the O-band to compensate for the abrupt shift in the intracavity power [3] and thereby enhance the soliton step size. This method simplifies the microcomb generation; however it requires a non-telecom band optical amplifier and components if the intracavity power contribution by the auxiliary laser exceeds O-band laser specifications. In this work, we operated both the pump and auxiliary laser in the telecom C-band and generated microcombs by launching them with orthogonal polarizations in counter-propagating directions. To utilize this comb for low-phase-noise applications, active feedback stabilization is necessary. Hence, we investigated the feasibility of employing the auxiliary laser frequency () as an actuator to stabilize the microcomb repetition rate frequency (). The sensitivity of was measured by modulating and the results demonstrate a linear relationship.
Schematic of the experimental setup