Ultra-high Q factor and low repetition rate optical fiber ring resonator with 1 inch-scale diameter

Abstract

Optical fiber ring resonator have utilized a wide range of applications, including in optical communication (WDM, filter, laser), chemical and health monitoring, many kind of sensor such as temperature, angular velocity, stress, pressure, and nonlinear optics and frequency comb (spectroscopy, time standards, optical and microwave generation, astronomical calibration, and laser ranging). Many researchers have tried to find a resonator with an ultra-high Q factor in a low repetition rate. Recently, they are developing a resonator in a small size that generates ultra-high Q factor and high pulse repetition rate typically in tens of GHz to several THz instead of less than 10 GHz. The resonator in miniature size has consuming high cost and complexity in fabrication. This research presents a fabrication method for optical ring resonator ultra-high Q factor using a wet etching method with hydrofluoric acid-based droplets and surface tension driven flows. Optical fiber has low loss and flexible transparent fiber which promising candidates to make optical fiber ring in simple and low cost. Optical fiber ring made by two ends of optical fiber is spliced together to form a loop. We reported that our research had achieved ultra-high Q factor $1.51 x 10^8$, and the repetition rate is ~2.56 GHz at 1550 nm wavelength in 25.5-millimeter (~1 inch) diameter optical fiber ring. Those low repetition rate optical fiber rings will be suitable for photodetector specification and spectroscopy, sensing and other applications.