The Generation And Regulation Of Optical Frequency Combs Based On High-Q Micro-ring Resonators

The generation of optical frequency combs?OFCs?via the Kerr nonlinearity has attracted significant interest and these devices based on micro-resonators can be used for comb systems.These comb systems are widely used in the fields of spectroscopy,optical communication,ranging,frequency synthesis and optical clocks.Especially solitons,a kind of high stability of Kerr combs with large comb line density,have good optical signal-to-noise ratio.Such Kerr combs exhibit enormous advantages for dense wavelength-division multiplexing?WDM?optical communications.In this thesis,the theory of the formation of Kerr OFCs is studied,We experimentally demonstrate the generation of Kerr OFCs based on silicon nitride?Si₃N₄?micro-ring resonator and lithium niobate?LN?micro-ring resonator.The main contents of this thesis are as follows:?1?The LLE is solved to study the formation of the Kerr OFCs and different state of solitons are realized in a micro-ring resonator by numerical simulation.To achieve broadband OFC,we numerically calculate the group-velocity dispersion?GVD?of different waveguides using a Finite-Difference Eigenmode solver.The Si₃N₄ waveguide with flat and low dispersion over a wide bandwidth is designed.?2?We experimentally demonstrate the generation of Kerr OFCs based on Si₃N₄ micro-ring resonator.Compared to the measured OFCs spectrum based on the waveguide with a cross section of 0.8?m×1.5?m,the waveguide with a cross section of 0.8?m×2.0?m achieved a wider rang optical frequency comb generation.The result agrees very well with the dispersion simulations.An OFC over a wavelength span of 600 nm is achieved.Through combining the feedback loop and tuning the passband of the tunable filter,OFCs with the comb spacing varying from 1 to 6-fold FSRs are successfully achieved.?3?A LN micro-ring is fabricated.There are two modes in the micro-ring,and the quality factors of different modes are 6.88×10⁵ and 4.94×10⁵,corresponding to 1542.05nm and 1542.31nm.We pump the LN micro-ring and have observed the OFCs generation.