Tunable, Single-Wavelength Fiber Laser Based on Hybrid Microcavity Functionalized by Atomic Layer Deposition

A tunable fiber laser based on a high-quality-factor (high-
Q
) hybrid microcavity (HM) is proposed and demonstrated. As far as we know, this is the first report of fabricating the HM by coating TiO
₂
film with varied thickness on the SiO
₂
microsphere surface by atomic layer deposition technique, with the
Q
-factor maintained to be above 10
⁷
. Ultra-narrow bandwidth whispering gallery mode spectrum of the HM is used for mode-selection in a double-ring fiber cavity, achieving tunable single-wavelength fiber laser output with 3dB bandwidth of about 16.20 pm, signal-to-noise ratio of ∼40 dB and wavelength tuning range of ∼220 pm. The proposed novel tunable, single-wavelength fiber laser with wide tuning range and high compactness can be potentially used for optical communication and sensing applications. © 2022 Optica Publishing Group.