Wavelength-tunable Thulium-doped Fiber Laser Research Articles

Multi-wavelength-tunable thulium-doped fiber laser generation based on dual-pass Mach–Zehnder and Sagnac loop hybrid filters

A wavelength-tunable thulium-doped fiber laser (TDFL) based on a Mach–Zehnder (MZ) filter and Sagnac loop was proposed in this study. The dual-pass MZ fiber filter, and Sagnac loop were fabricated to operate as reflectors in a linear cavity. The laser operating threshold was set to 138 mW. A single-wavelength laser output with an optical signal-to-noise ratio (OSNR) of up to 38 dB was realized with a tuning range of 1854–1882 nm. The tuning range was obtained with a tuning interval of 6 nm by tuning the polarization controller (PC), which yielded a power shift of less than 0.42 dB. Stability of the single-wavelength center wavelength power fluctuation was less than 0.39 dB within 20 min. When the laser was operated in the dual-wavelength condition, the OSNR was more than 30.5 dB, and the power fluctuation was less than 0.89 dB within 20 min at room temperature. The tunable triple-wavelength laser emission could be realized experimentally by adjusting the PC, which yielded an OSNR of more than 30.8 dB. The proposed TDFL is suitable for fiber-sensing system applications.

Wavelength-Flexible Thulium-Doped Fiber Laser Based on Digital Micromirror Array

Wavelength-tunable thulium-doped fiber laser is demonstrated employing a digital micromirror device (DMD) in combination with a fixed grating. The diffraction property of four typical models of DMDs and its steering efficiency for the laser system are analyzed based on two-dimensional grating theory. By spatially modulating reflective patterns on a DMD, the stable, fast, and flexible tuning of lasing wavelength from 1930 nm to 2000 nm is achieved with wavelength tuning accuracy of 0.1 nm. The side-mode suppression ratio is larger than 50 dB around the 2 μm band with 3 dB linewidth less than 0.05 nm. The wavelength drift and power fluctuation are lower than 0.05 nm and 0.1 dB within 1 h at the room temperature, respectively.

Wavelength-tunable thulium-doped fiber laser with sampled fiber Bragg gratings

A continuous wave (CW) wavelength-tunable Tm3+-doped fiber laser with two sampled fiber Bragg gratings (SFBGs) has been proposed and demonstrated. This proposed laser is stable operating with a significant 14.44 nm wavelength range from 1942.09 nm to 1956.53 nm due to the Vernier effect. The laser OSNRs of different wavelengths ranged from 45 dB to 58 dB at a launched pump power of 3.67 W. The wavelength shift and power fluctuation were less than 0.03 nm and 0.46 dB, respectively. An 8.62% slope efficiency was achieved using a grating for laser extracting. To the authors’ knowledge, this is the first time that a wavelength-tunable Tm3+-doped fiber laser with two SFBGs has been demonstrated.

All-fiber wavelength-tunable Tm-doped fiber laser mode locked by SESAM with 120 nm tuning range.

We demonstrate an all-fiber widely wavelength-tunable thulium-doped fiber laser (TDFL) mode locked by a semiconductor saturable absorber mirror (SESAM). The tuning range spans 121 nm, from 1862 nm to 1983 nm. The central wavelength is tuned by a grating-based tunable filter in the ring laser cavity. To the best of our knowledge, this is so far the most widely wavelength-tunable TDFL mode locked by SESAM.

Wavelength-tunable thulium-doped fiber laser by employing a self-made Fabry–Perot filter

In this demonstration, we proposed a novel wavelength-tunable thulium-doped fiber laser (TDFL) with a self-made Fabry–Perot (F–P) filter. When the F–P filter was not inserted, the maximum output power of 11.1 W was achieved when the pump power was 70.2 W. The corresponding optical-to-optical conversion efficiency was 15.8% and the slope efficiency was 22.1%. When the F–P filter was inserted, the output wavelength could be tuned from 1952.9 to 1934.9 nm with the change of cavity length of F–P filter which was fixed on a piezoelectric ceramic transducer (PZT) controlled by the voltage applied to it. The full width at half maximum (FWHM) was no more than 0.19 nm. Furthermore, the wavelength fluctuations of the tunable fiber laser were kept within ±0.2 nm.

High-power all-fiber wavelength-tunable thulium doped fiber laser at 2 μm

Power scaling of an all-fiber wavelength-tunable thulium doped fiber laser (TDFL) based on a monolithic master oscillator power amplifier (MOPA) system is presented. The whole configuration is comprised of a low-power seed oscillator and two stages of double-cladding thulium doped fiber amplifiers (TDFAs). The tuning of the operating wavelength is realized by inserting a spectral tunable filter into the seed oscillator. Maximum average output power of 115 W is obtained at 1950 nm with a linearly fitted slope efficiency of 51.7%. This laser has superior spectral characteristics with wavelength tunable from 1940 nm to 2070 nm. To the best of our knowledge, this is the first demonstration of an all-fiber wavelength-tunable TDFL at 2 μm with output power exceeding 100 W. The results are of great interest for many application areas.