Tm-doped All-fiber Laser Research Articles

The Theoretical and Experimental Study on High Power Quasi Single Mode Tm-Doped All-Fiber Laser at 1908 Nm

Thulium-doped all-fiber lasers at wavelength of 1908 nm have developed rapidly because of more applications. In this paper, a quasi single mode thulium-doped quasi single mode all-fiber laser is reported, which can generate laser powers of 30.8 W in oscillator and 83.5 W in amplifier at wavelength of 1908 nm. The slope efficiencies are 43.93% and 55.65%, respectively. Besides, the effect of active fiber length on the conversion efficiency are studied theoretically and experimentally. The results show that optimal fiber length could improve the cross-relaxation process and pump utilization. Based on the thermal conduction equations, experiments theoretically study the cooling temperature and the coefficient of convective heat transfer impacted on thermal management to obtain high laser power output.

Switchable Dual-Wavelength Tm-Doped All-Fiber Laser Integrating a Fiber Tip Modal Interferometer

A switchable dual-wavelength thulium-doped all-fiber laser incorporating a fiber tip modal interferometer (FTMI) is reported. The FTMI relies on the splice joint between a standard single-mode optical fiber and a tapered microfiber with 60- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> uniform waist diameter, providing a spectral reflection response that allows the laser to emit beyond 2000 nm, specifically at 2009.20 nm and 2013.65 nm, under a dual-wavelength operation regime. Besides, switching between both laser lines is also observed and controlled by adjustments of the intracavity polarization state, obtaining the ability to operate in a single-wavelength regime at either 2009 nm or 2013 nm. Laser emission lines exhibit linewidths of around 50 pm, side-mode suppression ratios higher than 50 dB and maximum output power of 13.4 mW.

Ultra-broadband tunable and switchable multi-wavelength mode-locking Tm-doped all-fiber laser

Through regulating the in-band absorption of used gain fiber, we demonstrate an ultra-broadband tunable and switchable multi-wavelength mode-locking Tm-doped all-fiber laser. The tuning range can be enlarged as much as 153 nm (from 1828.45 to 1981.35 nm, the largest tuning range so far) by employing different lengths of used gain fiber with different in-band absorption and birefringent filtering mechanism. In addition, benefiting from four in-line polarization controllers and broadband gain profile of Tm-doped fiber, switchable quad-wavelength mode locking with part binary control can be observed clearly, even penta-wavelength. Such kind of ultra-broadband tunable and switchable mode-locking laser provide simpler and elastic way for practical application, such as optical signal processing, spectroscopy, optical communications, and so on.

Supercontinuum source directly from noise-like pulse emission in a Tm-doped all-fiber laser with nonlinear polarization rotation

Supercontinuum (SC) generation directly from noise-like pulse (NLP) emission is demonstrated in a mode-locked thulium-doped all-fiber laser with nonlinear polarization rotation. The laser supports NLP emission at a repetition rate of 812.79 kHz, producing optical pulses of 2 ns pulse duration and 400 nm of optical bandwidth, which expands from 1800 nm to 2200 nm at floor level and covers the entire thulium band. The SC source presents a high dynamic range, higher than 50 dB, a high degree of spectral flatness, without significant spectral variations or pump remnants, and an output average power of 20.25 mW. Moreover, our proposal avoids the inclusion of external components and devices, thus preserving the robustness and simplicity in a single all-fiber system.

High-Power and Large-Energy Dissipative Soliton Resonance in a Compact Tm-Doped All-Fiber Laser

We report the direct generation of high-power and large-energy dissipative soliton resonance square pulses at 1940.8 nm from a compact mode-locked Tm-doped all-fiber laser. A fiber loop mirror of 10/90 splitting ratio and a fiber Bragg grating with high reflectivity of >99% constitute the cavity mirrors together. The fiber loop mirror not only acts as a broadband reflective mirror and output port but also initiates the mode-locked fiber laser. The strictly all-fiber structure and proper selection of fiber types allow the laser to work in a high pump power state. By increasing the pump power, pulse duration extends from 5.9 to 14.5 ns, while the pulse peak power and 3-dB spectrum bandwidth almost keep constant. At the maximum pump power of 13 W, we acquire maximum output average power of 1.98 W and single pulse energy of 684 nJ. To the best of our knowledge, this is the highest average output power and single pulse energy in an all-fiber Tm-doped mode-locked oscillator. At the same time, the output power is also a record value in all-fiber net anomalous dispersion oscillators.

High-performance Ho:YAG single-crystal fiber laser in-band pumped by a Tm-doped all-fiber laser.

We report on, to the best of our knowledge, the first Q-switched single-crystal fiber (Ho:YAG SCF) laser in the 2μm spectral range, in-band pumped by a Tm-doped all-fiber laser. A continuous-wave laser with 12.5W output power and Q-switched laser with 1.44mJ pulse energy and 7.5ns pulse duration at a repetition rate of 1kHz were demonstrated. The high laser performance is attributed to the high gain, suppressed nonlinear effects, and easy thermal management which benefited from the unique geometric construction of the SCF.

65-fs Pulses at 2 $\mu \text{m}$ in a Compact Tm-Doped All-Fiber Laser by Dispersion and Nonliearity Management

We report a compact ultrafast thulium-doped all-fiber laser delivering 65-fs pulses through nonlinear compression in a dispersion and nonlinearity managed fiber chain. The laser outputs 560-mW, 3.2-nJ pulses with a very broad bandwidth >160 nm at the central wavelength of 1980 nm. Numerical simulation investigates and verifies the formation and evolution of the ultrafast pulse.

Dispersion-compensation-free femtosecond Tm-doped all-fiber laser with a 248 MHz repetition rate.

In this Letter, we report a dispersion-compensation-free ultrafast thulium-doped all-fiber laser based on nonlinear polarization evolution (NPE) mode locking, delivering 330 fs soliton pulses at 1950 nm. A multifunctional hybrid fiberized device was applied in the oscillator to minimize the physical cavity length to ∼80 cm with a total dispersion of -0.045 ps2, enabling a state-of-the-art fundamental mode-locking repetition rate of 248 MHz in an NPE-based oscillator at ∼2 μm.

Amplification of noise-like pulses generated from a graphene-based Tm-doped all-fiber laser.

We report on the generation of noise-like pulse (NLP) trains in a Tm-doped fiber laser mode-locked by multilayer graphene saturable absorber. The spectral bandwidth obtained directly from the oscillator exceeds 60 nm, centered at 1950 nm, with 23.5 MHz repetition rate. The pulses were also amplified in a fully fiberized amplifier based on a double-cladding Tm-doped fiber. The system was capable of delivering 1.21 W of average power, which corresponds to 51.5 nJ energy stored in the noise-like bundle. We believe that the presented source might serve as a pump for supercontinuum generation in highly nonlinear fibers.

Ultra-broadband dissipative soliton and noise-like pulse generation from a normal dispersion mode-locked Tm-doped all-fiber laser.

We report generation of ultra-broadband dissipative solitons and noise-like pulses from a simple, fully fiberized mode-locked Tm-doped fiber laser. The oscillator operates in the normal net dispersion regime and is mode-locked via nonlinear polarization evolution. Depending on the cavity dispersion, the laser was capable of generating 60 nm or 100 nm broad dissipative solitons. These are the broadest spectra generated from a normal dispersion mode-locked Tm-doped fiber laser so far. The same oscillator might also operate in the noise-like pulse regime with extremely broad emission spectra (over 300 nm), which also significantly outperforms the previous reports.

All-polarization maintaining, graphene-based femtosecond Tm-doped all-fiber laser.

We report an all-fiber, all-polarization maintaining (PM) ultrafast Tm-doped fiber laser mode-locked by a multilayer graphene-based saturable absorber (SA). The laser emits 603 fs-short pulses centered at 1876 nm wavelength with 6.6 nm of bandwidth and 41 MHz repetition rate. Graphene used as saturable absorber was obtained via chemical vapor deposition (CVD) on copper substrate and immersed in a poly(methylmethacrylate) (PMMA) support, forming a stable, free-standing foil containing 12 graphene layers, suitable for the use in a fiber laser. The generated 603 fs pulses are the shortest reported pulses achieved from a Tm-doped laser mode-locked by graphene saturable absorber so far. Additionally, this is the first demonstration of an all-PM Tm-doped fiber laser incorporating a graphene-based SA. Such cost-effective, compact and stable fiber lasers might be considered as sources usable in nonlinear frequency conversion, mid-infrared spectroscopy and remote sensing.