Silicon carbide has recently emerged as a promising photonics material due to its unique properties,including possessing strong second-and third-order nonlinear coefficients and hosting various color centers that can be utilized for a wealth of quantum applications.Here,we report the design and demonstration of octave-spanning microcombs in a 4H-silicon-carbide-on-insulator platform for the first time,to our knowledge.Such broadband operation is enabled by optimized nanofabrication achieving＞1 million intrinsic quality factors in a 36-μm-radius microring resonator,and careful dispersion engineering by investigating the dispersion properties of differ-ent mode families.For example,for the fundamental transverse-electric mode whose dispersion can be tailored by simply varying the microring waveguide width,we realized a microcomb spectrum covering the wavelength range from 1100 nm to 2400 nm with an on-chip power near 120 mW.While the observed comb state is verified to be chaotic and not soliton,attaining such a large bandwidth is a crucial step towards realizing f-2f self-referencing.In addition,we also observed a coherent soliton-crystal state for the fundamental transverse-magnetic mode,which exhibits stronger dispersion than the fundamental transverse-electric mode and hence a narrower bandwidth.

Department of Electrical and Computer Engineering,Carnegie Mellon University,Pittsburgh,Pennsylvania 15213,USA

[1]LUTONG CAI;JINGWEI LI;RUIXUAN WANG;QING LI-.Octave-spanning microcomb generation in 4H-silicon-carbide-on-insulator photonics platform)[J].光子学研究（英文）,2022(04):870-876

octave

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