Dissipative Kerr solitons in optical microresonators with Raman effect and third-order dispersion

Using the mean-field normalized Lugiato-Lefever equation,we theoretically investigate the dynamics of cavity soliton and comb generation in the presence of Raman effect and the third-order dispersion.Both of them can induce the temporal drift and frequency shift.Based on the moment analysis method,we analytically obtain the temporal and frequency shift,and the results agree with the direct numerical simulation.Finally,the compensation and enhancement of the soliton spectral between the Raman-induced self-frequency shift and soliton recoil are predicted.Our results pave the way for further understanding the soliton dynamics and spectral characteristics,and providing an effective route to manipulate frequency comb.

Soliton formation and spectral translation into visible on CMOS-compatible 4H-silicon-carbide-oninsulator platform

Recent advancements in integrated soliton microcombs open the route to a wide range of chip-based communication,sensing,and metrology applications.The technology translation from laboratory demonstrations to real-world applications requires the fabrication process of photonics chips to be fully CMOS-compatible,such that the manufacturing can take advantage of the ongoing evolution of semiconductor technology at reduced cost and with high volume.Silicon nitride has become the leading CMOS platform for integrated soliton devices,however,it is an insulator and lacks intrinsic second-order nonlinearity for electro-optic modulation.Other materials have emerged such as AlN,LiNbO_(3),AlGaAs and GaP that exhibit simultaneous second-and third-order nonlinearities.Here,we show that silicon carbide(SiC)--already commercially deployed in nearly ubiquitous electrical power devices such as RF electronics,MOSFET,and MEMS due to its wide bandgap properties,excellent mechanical properties,piezoelectricity and chemical inertia--is a new competitive CMOS-compatible platform for nonlinear photonics.High-quality-factor microresonators(Q=4×10^(6))are fabricated on 4H-SiC-on-insulator thin films,where a single soliton microcomb is generated.In addition,we observe wide spectral translation of chaotic microcombs from near-infrared to visible due to the second-order nonlinearity of SiC.Our work highlights the prospects of SiC for future low-loss integrated nonlinear and quantum photonics that could harness electro-opto-mechanical interactions on a monolithic platform.

Electro-optically tunable microdisk laser on Er^(3+)-doped lithium niobate thin film

We report an electro-optically(EO)tunable microdisk laser fabricated on the erbium(Er^(3+))-doped lithium niobate on insulator(LNOI) substrate.By applying a variable voltage on a pair of integrated chromium(Cr) microelectrodes fabricated near the LNOI microdisk,electro-optic modulation with an effective resonance-frequency tuning rate of 2.6 GHz/100 V has been achieved.This gives rise to a tuning range of 45 pm when the electric voltage is varied between-200 V and 200 V.

High-quality-factor optical microresonators fabricated on lithium niobate thin film with an electro-optical tuning range spanning over one free spectral range [Invited]

We demonstrate high-quality(intrinsic Q factor∼2.8×106)racetrack microresonators fabricated on lithium niobate thin film with a free spectral range(FSR)of∼86 pm.By integrating microelectrodes alongside the two straight arms of the racetrack resonator,the resonance wavelength around 1550 nm can be red shifted by 92 pm when the electric voltage is raised from−100 V to 100 V.The microresonators with the tuning range spanning over a full FSR are fabricated using photolithography assisted chemo-mechanical etching.

Bound states in the continuum in all-dielectric metasurfaces with scaled lattice constants

Bound states in the continuum(BICs)have emerged as an efficient tool for trapping light at the nanoscale,promising several exciting applications in photonics.Breaking the structural symmetry has been proposed as an effective way of exciting quasiBICs(QBICs)and generating high-Q resonances.Herein,we demonstrate that QBICs can be excited in an all-dielectric metasurface by scaling the lattice of the metasurface,causing translational symmetry breaking.The corresponding BICs arise from band folding from the band edge to the Γ point in the first Brillouin zone.Multipole analysis reveals that the toroidal dipole dominates these QBICs.Furthermore,scaling the lattice along different directions provides additional freedom for tailoring QBICs,enabling polarization-dependent or-independent QBICs.In addition,this allows the realization of two QBICs at different wavelengths using plane-wave illumination with different polarizations on the metasurface.We experimentally demonstrated the existence of these BICs by fabricating silicon metasurfaces with scaled lattices and measuring their transmission spectra.The vanished resonant linewidth identifies BICs in the transmission spectrum,and the QBICs are characterized by highQ Fano resonances with the Q-factor reaching 2000.Our results have potential applications in enhancing light-matter interaction,such as laser,nonlinear harmonic generation,and strong coupling.