26th Australian Institute of Physics Congress and the Australian and New Zealand Conference on Optics and Photonics

Tapered Fibre Fabry-Pérot Cavities for the Generation of Broadband and Near-Visible Kerr Frequency Combs

Not scheduled

20m

Belinda Hutchinson Building (The University of Sydney )

Contributed Oral ANZOS | Photonics and Optics (ANZCOP)

Description

Passive Kerr frequency combs generated within coherently driven cavities have been shown to have huge application potential, ranging from spectroscopy to ultra-fast imaging. While the generation of high-quality Kerr combs in the near-infrared is easily achievable, the same cannot be said for visible and near-visible Kerr comb generation. Due to the strong normal dispersion of nearly all materials at shorter wavelengths, generating broadband Kerr combs at near-visible and visible wavelengths remains problematic.

In this work, we demonstrate near-visible broadband Kerr frequency comb generation at 770 nm in a synchronously driven tapered fibre Fabry–Pérot (TFFP) resonator. By incorporating a micron-diameter tapered silica fibre section into a fibre cavity, we exploit geometric dispersion engineering to overcome the strong normal material dispersion that typically limits broadband Kerr comb generation at short wavelengths. Moreover, the micron-diameter taper at the centre of our resonator simultaneously enhances the optical Kerr nonlinearity through strong mode confinement, reducing the power threshold for nonlinear structure formation to levels typically seen within microresonators. By varying the length of untapered fibre within our TFFP resonators, we can tailor the average cavity dispersion from anomalous to near-zero and normal regimes around a pump wavelength of 770 nm. This enables the generation of a diverse range of coherent, phase-locked nonlinear states within a single platform, including anomalous-dispersion cavity solitons, zero-dispersion solitons, switching-wave frequency combs, and Raman solitons. Furthermore, the near-visible zero-dispersion and Raman solitons generated within this work exhibit spectral bandwidths exceeding 16 THz, representing the broadest phase-locked Kerr-generated structures reported in the near-visible regime to date.

These results establish tapered fibre Fabry–Pérot resonators as a versatile and highly controllable platform for near-visible coherent frequency comb generation, and provide a promising route towards future passive Kerr soliton generation in the visible spectrum.