Soliton Optical Frequency Comb Research Based On High-index Doped Silica Glass Microresonator

Benefiting from low power consumption,high coherence,broad bandwidth and easy-to-integrate ability,high Q microresonator based Kerr soliton optical frequency comb(soliton microcomb)has shown unprecedented advantage in the fields of ultrafast precision ranging,dual-comb spectroscopy,optical frequency synthesis,etc.In recent years,high-index doped silica materials platform has been attractive for its CMOS process compatibility,low loss,mature coupling and packaging techniques.In this dissertation,based on high-index doped silica glass microresonator,the generation process and the dynamics of soliton microcomb is investigated both in theory and experiment.Theoretically,harmonic and sub-harmonic phase-modulation pump scheme are proposed for investigating the generation dynamics of soliton microcomb with higher-order repetition rate.Based on mode coupling and thermal tuning resonance methods,modelocked soliton crystal microcomb with various spectral features are obtained.Based on orthogonal-polarized auxiliary laser heating scheme,single soliton generation dynamics is studied.Finally,three proof-of-concept experiments based on single soliton source are demonstrated.The main contents and conclusions obtained are summarized as follows:1.Harmonic phase modulation pump scheme is proposed,1-4 equidistant soliton states(repetition rate: ～10 GHz-～40 GHz)are realized deterministically.The Raman scattering effect is also investigated。To realize soliton microcomb with even higher repetition rate,sub-harmonic phase modulation scheme is applied,by designing and optimizing the modulation frequency and pump efficiency parameters,5-20 equidistant soliton is realized in a single microcavity,the corresponding repetition rate ranges from～50 GHz-～200 GHz.2.Based on mode coupling effect and thermal tuning resonance method,soliton crystal microcomb with more than 200 nm bandwidth and various spectral features are obtained.Furthermore,taking the wavelength-dependent loss parameters into numerical model,the Raman shock time for high-index doped silica material is calculated as2.5 fs-2.7 fs by precisely comparing the simulated and experimental spectrum.3.By inducing a counter-propagating auxiliary laser that is co-or orthogonal polarized with the pump laser,the intracavity thermal instability is balanced timely,highindex doped silica glass microresonator based single solitons are first realized,the repetition rate is ～48.97 GHz(spectral range ～160 nm)and ～26.09 GHz(spectral range～80 nm),respectively.By tuning the temperature of the TEC,the center wavelength of dispersive wave could be tuned.Based on single soliton microcombs,three proof-ofconcept applications are demonstrated: 1,based on dispersive interferometry method,the absolute distance of ～1179 m is measured with Allen deviation less than 27 nm;2,based on two single-soliton with ～600 k Hz repetition rate difference,the absorption spectrum of HCN at 1530 nm-1560 nm is measured,7 comb lines with more than 3 d B absorption intensity is observed;3,soliton microcomb temporal characterization based on heterodyne beat sampling method using another single soliton microcomb,single-,two-,three-and five-soliton state is characterized.