Degenerate four-wave-mixing in a silica hollow bottle-like microresonator

TL;DR

This paper demonstrates degenerate four-wave mixing in a high-Q silica hollow bottle-like microresonator with nearly zero waveguide dispersion, highlighting its potential for generating wide frequency combs in telecommunications.

Contribution

It introduces a novel hollow bottle-like microresonator with ultra-high Q and analyzes its dispersion properties for four-wave mixing applications.

Findings

Degenerate FWM observed at 1.55 μm in the BLMR

Parabolic profile ensures nearly zero waveguide dispersion

Dispersion tuning discussed and potential for frequency combs

Abstract

A hollow bottle-like microresonator (BLMR) with ultra-high quality factor is fabricated from a microcapillary with nearly parabolic profile. At 1.55 $\mu m$ pumping, degenerate four-wave mixing can be observed for a BLMR of diameter 102 $\mu$m. The parabolic profile of the BLMR guarantees a nearly zero waveguide dispersion, which is theoretically discussed in detail. From the simulation, at 1.55 $\mu$m wavelength in such a BLMR, the fundamental bottle mode is in the anomalous dispersion regime, whilst the ordinary whispering gallery mode (WGM) confined at the center of the BLMR is in the normal dispersion regime. Experimentally, no degenerate FWM is observed for the WGM selected by positioning the coupling tapered fiber in the same BLMR. Furthermore, dispersion tuning is briefly discussed. As the work predicted, the BLMR shows promise for the implementation of sparsely distributed, widely spanned frequency combs at the telecommunication wavelength.