Photonic chip-based soliton frequency combs covering the biological imaging window

Maxim Karpov,Anton Lukashchuk,Tobias J Kippenberg,Junqiu Liu,Martin H P Pfeiffer

doi:10.1038/s41467-018-03471-x

Maxim Karpov, Anton Lukashchuk + Show 3 more

Open Access

https://doi.org/10.1038/s41467-018-03471-x

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Abstract

Dissipative Kerr solitons (DKS) in optical microresonators provide a highly miniaturised, chip-integrated frequency comb source with unprecedentedly high repetition rates and spectral bandwidth. To date, such frequency comb sources have been successfully applied in the optical telecommunication band for dual-comb spectroscopy, coherent telecommunications, counting of optical frequencies and distance measurements. Yet, the range of applications could be significantly extended by operating in the near-infrared spectral domain, which is a prerequisite for biomedical and Raman imaging applications, and hosts commonly used optical atomic transitions. Here we show the operation of photonic-chip-based soliton Kerr combs driven with 1 micron laser light. By engineering the dispersion properties of a Si3N4 microring resonator, octave-spanning soliton Kerr combs extending to 776 nm are attained, thereby covering the optical biological imaging window. Moreover, we show that soliton states can be generated in normal group–velocity dispersion regions when exploiting mode hybridisation with other mode families.

Highlights

Dissipative Kerr solitons (DKS) in optical microresonators provide a highly miniaturised, chipintegrated frequency comb source with unprecedentedly high repetition rates and spectral bandwidth
It was recently demonstrated that such CW laser-driven microresonators can support the spontaneous formation of dissipative Kerr solitons[3] (DKS)— self-organised stable intracavity pulses relying on the double balance between dispersion and nonlinearity[4], and parametric gain and cavity losses—which provide a route to fully coherent optical frequency combs whose spectral bandwidth can be significantly broadened via soliton-induced Cherenkov radiation[5,6,7]
In the context of microresonator-based Kerr frequency combs, the dispersion properties are often expressed through the frequency deviations from an equidistant grid for a certain pumped mode ω0 in the rtmDhe1lieaμctr)cioav=rveeiPstyomnir>oae1dtsoDeorni3μia.nin=dFcie!eo,x,ria2n(bμdrN)igD2,πhr1wetipshrDetehrsKeeeSnωftrμaegteieis-onsnteph:reeacDttaironiannglt(,urμla)aintr=gfeirωse(μqFg−uSeeRnn()eωcroy0af+lolyaf required to achieve anomalous group–velocity dispersion (GVD): D2 > 0, which can be especially challenging at short wavelengths

Summary

Introduction

Dissipative Kerr solitons (DKS) in optical microresonators provide a highly miniaturised, chipintegrated frequency comb source with unprecedentedly high repetition rates and spectral bandwidth. We demonstrate that Si3N4 microresonators can overcome these challenges and the DKS-based frequency combs can be generated with a 1060 nm CW laser, thereby allowing access to the optical wavelength window for biological imaging (0.7–1.4 μm).

Results

Conclusion