Fig. 2: Efficient soliton generation in resonators with interferometric back-coupling.
From: Efficient Kerr soliton comb generation in micro-resonator with interferometric back-coupling
a Experimental setup and picture of a chip containing two ring resonators with feedback (A and B). TBP tunable band-pass filter, PD photodiode, OSA optical spectrum analyzer, ESA electrical spectrum analyzer. The loaded Q-factor = \(\frac{{\omega }_{0}}{{{\Delta }}{\omega }_{{{{{{{{\rm{T}}}}}}}}}}\), where ω0 is the pump frequency and ΔωT is the loaded linewidth of the resonance. b Measured dispersion of the free-spectral range in resonator A featuring anomalous dispersion. Dint(μ) = ωμ − (ω0 + D1μ) is the deviation from an ideal equally spaced frequency grid, where ω0 is the central frequency and \({\omega }_{\mu }\,=\,{\omega }_{0}+{D}_{1}\mu +\frac{1}{2}{D}_{2}{\mu }^{2}+\frac{1}{6}{D}_{3}{\mu }^{2}+....\) are the frequencies of the resonances. \(\frac{{D}_{1}}{2\pi }\) is the free-spectral range (FSR) of the micro-resonator while D2 and D3 are the second- and third-order dispersion coefficients. c Output power of the generated comb as a function of the pump-resonator detuning. The different colors represent consecutive pump scanning through the resonance. d Repetition rate signal of the soliton crystal with defect shown in h. Frequency comb spectra featuring a e perfect soliton crystal and f–h soliton crystals with defect. The pump depletion values indicated in red are measured with respect to the input power.
