Dispersion engineering and measurement of whispering gallery mode microresonator for Kerr frequency comb generation

Abstract

<jats:title>Abstract</jats:title><jats:p>Designing and engineering microresonator dispersion are essential for generating microresonator frequency comb. Microresonator frequency combs (microcombs, Kerr frequency combs) offer the potential for various attractive applications as a new type of coherent light source that is power efficient and compact and has a high repetition rate and a broad bandwidth. They are easily driven with a continuous-wave pump laser with adequate frequency tuning; however, the resonators must have a high quality (<jats:italic>Q</jats:italic>) factor and suitable dispersion. The emergence of cavity enhanced four-wave mixing, which is based on third-order susceptibility in the host material, results in the generation of broadband and coherent optical frequency combs in the frequency domain equivalent to an optical pulse in the time domain. The platforms on which Kerr frequency combs can be observed have been developed, thanks to intensive efforts by many researchers over a few decades. Ultrahigh-<jats:italic>Q</jats:italic> whispering gallery mode (WGM) microresonators are one of the major platforms since they can be made of a wide range of material including silica glass, fluoride crystals and semiconductors. In this review, we focus on the dispersion engineering of WGM microresonators by designing the geometry of the resonators based on numerical simulation. In addition, we discuss experimental methods for measuring resonator dispersion. Finally, we describe experimental results for Kerr frequency combs where second- and higher-order dispersions influence their optical spectra.</jats:p>

Kerr-Raman Optical Frequency Combs in Silica Microsphere Pumped Near Zero Dispersion Wavelength

“…To optimize the ZDW and find the required size of the silica MS, we calculated dispersion β 2 for different radii R using the approach based on numerical solution of a characteristic equation [26] as in our previous works [27,28]. We found eigenfrequencies ν l for the fundamental transverse electric mode families, where l is the azimuthal mode index, and after that we calculated β 2 as follows [29,30]:…”

High-Q microresonators on 4H-silicon-carbide-on-insulator platform for nonlinear photonics

“…In order to generate the broadband frequency comb, the record-high-Q factor of the current SiC microresonator facilitates generation of the optical parametric oscillation (OPO) followed by the cascaded frequency conversion processes of high efficiency thank to the low intracavity losses 42 . Besides, an anomalous group-velocity dispersion of the microresonator is also required to compensate for the nonlinear phase shift induce by self-phase modulation and cross-phase modulation 43 . To investigate the dispersion properties of the fabricated microresonator, we theoretically calculated the group-velocity dispersion (GVD) using a finite-element mode solver.…”

Design, Simulation, and Analysis of Optical Microring Resonators in Lithium Tantalate on Insulator

“…The characteristic frequency spectrum of the microring, which is dependent upon its size, is a defining factor in the transmission of a selected wavelength of light into another waveguide. The microring resonators are widely employed in the design and manufacture of optical filters [4][5][6], modulators [7,8], optical switches [9,10], optical delay lines [11], and Kerr frequency combs [12][13][14][15], etc. Multiple material systems have been used to fabricate microring resonators, such as silicon on insulator (SOI) [1,[16][17][18], silicon nitride (SiN) [5,19], and lithium niobate on insulator (LNOI) [20][21][22][23].…”