title: Four-wave mixing parametric oscillation and frequency comb generation at visible wavelengths in a silica microbubble resonator.
abstract: Frequency comb generation in microresonators at visible wavelengths has found applications in a variety of areas such as metrology, sensing, and imaging. To achieve Kerr combs based on four-wave mixing in a microresonator, dispersion must be in the anomalous regime. In this Letter, we demonstrate dispersion engineering in a microbubble resonator (MBR) fabricated by a two-CO2laser beam technique. By decreasing the wall thickness of the MBR to 1.4 μm, the zero dispersion wavelength shifts to values shorter than 764 nm, making phase matching possible around 765 nm. With the optical Q-factor of the MBR modes being greater than 107, four-wave mixing is observed at 765 nm for a pump power of 3 mW. By increasing the pump power, parametric oscillation is achieved, and a frequency comb with 14 comb lines is generated at visible wavelengths.
authors.forename: Yong
authors.initials: Y
authors.lastname: Yang
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Jiang
authors.forename: Sho
authors.initials: S
authors.lastname: Kasumie
authors.forename: Guangming
authors.initials: G
authors.lastname: Zhao
authors.forename: Linhua
authors.initials: L
authors.lastname: Xu
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Ward
authors.forename: Lan
authors.initials: L
authors.lastname: Yang
authors.forename: Síle Nic
authors.initials: SN
authors.lastname: Chormaic