Long-Length and Thermally Stable High-Finesse Fabry-Perot Interferometers Made of Hollow Core Optical Fiber
Meng Ding, Matěj Komanec, Dmytro Suslov, Daniel Dousek, Stanislav Zvánovec, Eric Numkam Fokoua, Thomas D. Bradley, Francesco Poletti, David J. Richardson, Radan Slavı́k
Abstract
We made and characterized two Fabry-Perot interferometer samples made of the latest-generation hollow core fiber with sub-1-dB/km loss. Thanks to this low transmission loss, we achieved a finesse of over 140 and 120, for interferometer lengths of 5 and 23 m, respectively. This resulted in transmission peaks as narrow as 47 kHz. Our all-fiber Fabry-Perot interferometers have standard single-mode fiber pigtails (for easy integration in conventional fiber optic systems) and employ fiber mode field adapters to enable low-loss coupling between the pigtails and the low-loss hollow core fiber. The high-reflectivity mirrors (>98%) were deposited directly on the fiber mode field adapters, which were glued to the hollow core fiber, resulting in permanently-aligned Fabry-Perot interferometers. We also measured how the position of the transmission peaks change with temperature (an important performance metrics for most applications, e.g., when used as a narrow-band band-pass filter) and found that it changed 14.5 times less in our Fabry-Perot interferometer relative to a similar device made of standard single mode fiber.