Switchable dual-wavelength Ho-doped fiber laser using thin core fiber filter operating at the extended 2 μm wavelength region

Abstract This work presents the demonstration of a switchable dual-wavelength Holmium-doped fiber laser (HDFL) utilizing a Mach–Zehnder Interferometer (MZI) based on a thin-core fiber filter (TCFF). The TCFF was fabricated by core-offset splicing both ends of a 6 cm UHNA3 fiber with single-mode fibers (SMF). The wavelength spacing of the comb spectrum of the TCFF was measured to be 3.48 nm. A dual-wavelength lasing was achieved after integrating the TCFF into an HDFL cavity. The lasings started at 2082.1 nm and 2085.6 nm with a 3.50 nm spacing between each peak. The OSNR for both peaks is more than 41 dB. The laser’s emission pair can be switched to other wavelengths, ranging from 2065.8 nm to 2089.5 nm. To the author’s knowledge, this work is the first to present switchable dual-wavelength in HDFL using a TCFF. The demonstrated switchable dual-wavelength HDFL in the extended 2 μm region provides new possibilities for applications in sensing, spectroscopy, and other fields requiring precise multiwavelength sources.