Mode-locked Tm Research Articles

Doubly Q-switched mode-locked Tm:YAP laser at [formula omitted] with ternary MoWS2 alloy and EOM

2D MoWS2 is fabricated by the chemical-vapor transport and liquid-phase exfoliation method. Its nonlinear optical response is measured. By using MoWS2 SA and EOM, an LD-pumped doubly Q-switched mode-locked (QML) Tm:YAP laser at 2μm waveband is presented. The average output power, the pulse width, and the pulse peak power of the Q-switched envelope are measured. In comparison to the singly QML laser with MoWS2 SA or EOM, the doubly QML laser can generate shorter pulse duration and higher peak power. Based on the fluctuation mechanism, a developed rate equation model under plane wave approximation is proposed to describe the doubly QML dynamic process. The pulse characteristics of QML laser are numerically simulated and the theoretical simulations are in agreement with the experiment results. Both the experiments and numerical simulations show that MoWS2 is a promising nanomaterial, and the dual-loss-modulated QML laser displays well performance in pulse width compression and peak power enhancement.

Broadband saturable absorption in germanene for mode-locked Yb, Er, and Tm fiber lasers.

Passively mode-locked lasers have been widely investigated as one of the effective methods to obtain ultrashort pulses. As an important part of passively mode-locked fiber lasers, the exploration of 2D material-based saturable absorber has become one of the hotspots in ultrafast photonics in recent years. Germanene, a novel 2D Dirac material, with ultrafast optical response and broadband optical absorption, is a promising alternative material for saturable absorber in mode-locked fiber lasers. In this paper, germanium nanosheets are prepared via liquid-phase exfoliated method, with the saturable absorption property systematically characterized in three major wavebands of the near-infrared region. The generation of ultrashort pulses based on germanene saturable absorber in fiber lasers is further realized, in a broad waveband (1000nm) centered at 1061.1, 1559.3 and 1883.5nm, respectively. In addition, noise-like pulses operation with central wavelength of 1558.6nm is also obtained, and the formation of rogue waves is further demonstrated via statistical analysis. To the best of our knowledge, this is the first experimental verification of the broadband saturable absorption property of germanene-based devices, covering three major fiber laser wavelengths from 1.0 to 2.0μm.

1.7 µm gain-switched and mode-locked hybrid Tm-Ho codoped fiber laser signal generation and optimization.

We propose and experimentally demonstrate 1.7 µm gain-switched and mode-locked hybrid laser signal generation using a modulated pump and the nonlinear polarization rotation (NPR) effect. In the laser scheme, a 1.55 µm amplified modulated optical signal was used as a homemade pump. A bidirectional pumping configuration was adopted by splitting the homemade pump. A 1 m long thulium-holmium (Tm-Ho) codoped fiber was used as the gain medium. A fiber Bragg grating was employed as a spectral filter. The mode-locked laser pulse was obtained with a central wavelength of 1724 nm. The repetition rate was 11.81 MHz and the pulse width was 65.27 ps. Additionally, the gain-switched pulse sequences with a repetition rate from 50 kHz to 200 kHz were obtained by the modulated pump. Moreover, the mode-locked pulse train was filtered and modulated by the shape of the gain-switched pulse, and the hybrid pulse train was then obtained. Furthermore, the hybrid laser signals were analyzed and optimized by applying different waveforms of the modulated pump. The experimental results showed that the generated laser pulse driven by the sinusoidal signal has a better SNR (49.39 dB).

A passively mode-locked Tm:YAG laser with a titanium disulfide saturable absorber

Titanium disulfide (TiS2) material has been interest in an optics nonlinear due to its perfect optical, physical and chemical properties. However, there are few studies on TiS2 material as saturable absorber (SA) for ultrafast solid-state laser operating at 2-μm range. In this paper, we prepared TiS2 SA by using an ultrasonic thermolysis technique and demonstrated its saturable absorption characteristics by passively mode-locked (PML) technology. Under PML mode, Tm:YAG laser produced the maximum average output power of 102 mW at 2011.4 nm, corresponding to a shortest pulse duration of 224.0 ps at 208.5 MHz. To our knowledge, that is the narrowest pulse width from a PML Tm:YAG laser with a TiS2 SA.

Diode-pumped SESAM mode-locked low-repetition-rate Tm:CALGO picosecond laser at 1968 nm

A diode-pumped SESAM continuous-wave mode-locked (CWML) Tm:CALGO laser is demonstrated at a new center wavelength of 1968 nm based on a ultra-long Z-shaped folding cavity configuration. A total maximum dual-output power of 328 mW is achieved with a pulse duration of 33.2 ps at a repetition rate of 38.86 MHz, corresponding to a maximum single pulse energy of 4.2 nJ.

Self-mode-locking and self-phase modulation in Tm3+-doped double clad fiber laser for pulse peak power enhancement and multi-wavelength generation

A dual frequency mode-locked Tm3+-doped double clad fiber laser (TDCFL) is proposed by combining self-mode-locking with self-phase modulation (SPM) effect. The SPM effect stimulates the 24th harmonic mode-locking operation. The unpumped gain fiber-based self-mode-locking effect initiates the fundamental mode-locked operation. This fundamental mode-locked pulse acts as a modulation envelope of the 24th harmonic one. In this situation, the maximum pulse peak power and the largest pulse energy improve greatly. Its maximum pulse peak power is at least 311 times higher than the fundamental mode-locked one. And the difference of pulse energy is ~7.8 times. Furthermore, this dual frequency mode-locked TDCFL generates multi-wavelength light under high pump power. These results could offer an exciting new prospect for obtaining simple, compact and high performance multi-wavelength mode-locked fiber lasers.

Kerr-Lens Mode-Locked Tm Solid State Laser with Spectral Broadening Effect

Kerr-Lens Mode-Locked Tm Solid State Laser with Spectral Broadening Effect

Power-scalable sub-100-fs Tm laser at 2.08 μm

Abstract We report on a power-scalable sub-100-fs laser in the 2-μm spectral range using a Tm3+-doped ‘mixed’ (Lu,Sc)2O3 sesquioxide ceramic as an active medium. Pulses as short as 58 fs at 2076 nm with an average output power of 114 mW at a pulse repetition rate of approximately 82.9 MHz are generated by employing single-walled carbon nanotubes as a saturable absorber. A higher average power of 350 mW at 2075 nm is obtained at the expense of the pulse duration (65 fs). A maximum average power of 486 mW is achieved for a pulse duration of 98 fs and an optical conversion efficiency of 22.3%, representing the highest value ever reported from sub-100-fs mode-locked Tm lasers.

High single pulse energy passively Q-switched mode-locked Tm, Ho: LLF laser

High single pulse energy passively Q-switched mode-locked Tm, Ho: LLF laser

Mode-Locked Tm³⁺-Doped Fiber Laser With CV Mode Output Using a Cascading Chirped LPFG

A passively mode-locked Tm3+-doped fiber laser based on the mechanism of nonlinear polarization rotation and cascading chirped long period fiber grating (LPFG) to generate ultrafast cylindrical vector (CV) mode output is proposed and demonstrated. The fiber laser output traditional soliton pulses operating at 1878.8 nm with a 3 dB bandwidth of 3.94 nm. The pulse duration of the laser is ~1.05 ps with a repetition rate of 18.766 MHz. A cascading chirped LPFG, fabricated in a few-mode fiber by a CO2 laser, serves as a broadband transverse mode converter to achieve ultrafast CV mode generation. The LPFG has a 10 dB bandwidth (corresponding to conversion efficiency of 90%) of 20 nm from 1877 nm to 1897 nm, which perfectly covers the wide mode-locked spectrum. High purity radially and azimuthally polarized modes are obtained through adjusting the polarization controllers, and the mode purity is calculated to be about 95.1% and 94.9% for TE01 and TM01. To our best knowledge, this is the first mode-locked fiber laser emitting CV modes in $2~\mu \text{m}$ waveband using a broadband LPFG as a mode converter.

Optical and laser performances of a layered ReSe2 saturable absorber for a 2-µm solid laser

In this paper, a dispersion solution of rhenium diselenide (ReSe2) was prepared using an ultrasonic decomposition method and prepared for use as a saturable absorber (SA) mirror by spin-coating. The optical characteristics of the ReSe2 SA were characterized to acquire those parameters which were saturated at 2 μm. A passively mode-locked (PML) Tm:YAG laser with an ReSe2 SA was first demonstrated in an experiment. Under a continuous wave (CW) regime, a 1940-mW output power was achieved at 2013.8 nm with a pump power of 22.4 W. In PML mode, a 320-mW average output power and a 580.5-ps pulse duration at 203.1 MHz were acquired from the PML Tm:YAG laser with an output wavelength of 2012.6 nm, corresponding to a pulse energy of 1.58 nJ and an optical-optical conversion efficiency of 2.2%.

Continuous-wave mode-locked Tm:YAG laser with GaAs-based SESAM

Passive mode-locked laser operation at 2012 nm based on Tm:YAG and GaAs-based saturable absorber mirrors is demonstrated. Continuous-wave mode-locking performance was observed, resulting in a pulse width of 47.9 ps and 117 mW average output power at 97.7 MHz. The mode-locked laser exhibits an excellent stability with a remarkably high extinction ratio of 72 dB above carrier.

Mode-Locked Tm Fiber Laser With a Tapered GIMF SA Based on Nonlinear Multimode Interference Effect

We experimentally demonstrate a passively mode-locked all-fiber Tm laser with an all-fiber saturable absorber (SA) which operates based on the nonlinear multimode interference (NL-MMI) effect in a tapered graded-index multimode fiber (GIMF). The tapered GIMF SA demonstrates the nonlinear characteristics of modulation depth of 21.15%, and saturation fluence of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$89.04~\mu \text{J}$ </tex-math></inline-formula> /cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . We obtain stable fundamentally mode-locking operation at a pump threshold of 120 mW. The output soliton pulses have a center wavelength, spectral width, pulse duration and repetition rate of 1935 nm, 2.1 nm, 1.9 ps and 18.79 MHz, respectively. This is a simple, low-cost, stable, and convenient laser oscillator with many potential applications in eye-safe ultrafast photonics.

High quality-factor Kerr-lens mode-locked Tm:Sc2O3 single crystal laser with anomalous spectral broadening

We report on a high quality-factor Kerr-lens mode-locked Tm:Sc2O3 laser operating around 2.1 μm. Using a simple four mirror Z-shaped cavity consisting of an output coupler (OC) of 0.5% transmittance, two folding mirrors, and a chirped mirror, pulses as short as 72 fs with an average power of 130 mW were obtained at a center wavelength of 2108 nm. By replacing the 0.5% OC with a ∼0.3% one, we observed anomalous broadening of the spectrum into the range between ∼2250 and 2350 nm where Tm:Sc2O3 shows no gain.

Passively mode-locked diode-pumped Tm,Ho:LiYF4 laser

We report on the first demonstration of a diode-pumped passively mode-locked Tm,Ho:LiYF4 laser. Stable continuous-wave mode-locking is achieved by employing a single-layer graphene as a saturable absorber (SA). For a reflection-type graphene-SA, the laser delivers 5.2 ps pulses at ~2051 nm with an average output power of 40 mW at a repetition rate of 89.86 MHz. With a transmission-type graphene-SA and smaller output coupling, the output power is scaled up to 80 mW while the laser operated in a double-pulse regime.

7 W mid-infrared supercontinuum generation up to 4.7 μm in an indium-fluoride optical fiber pumped by a high-peak power thulium-doped fiber single-oscillator.

In this letter, a high-power supercontinuum (SC) generation is achieved in an InF3 fiber with a maximum all bands output power of 7 W and spectrum extension up to 4.7 μm. An actively Q-switched mode-locked (QML) Tm3+-doped fiber single-oscillator has been used to pump the fluoride fiber. At the average power level of 15 W, the most energetic QML pulse provided by the fiber laser had an energy of 88 μJ and an estimated peak power of 60 kW. To the best of our knowledge, this is the first experimental demonstration of a Watt-level range supercontinuum generation in an InF3 fiber pumped by a single-oscillator laser system.

Soliton Mode-Locked Large-Mode-Area Tm-Doped Fiber Oscillator

We report a passively mode-locked fiber oscillator based on thulium-doped large-mode-area (LMA) fiber. Reliably mode-locking soliton operation can be readily achieved after the suppression of the higher-order modes by using mode field adapters in combination with coiling fiber method. The laser delivers 600-fs level pulses at $2~\mu \text{m}$ with an average power of up to 243 mW and a repetition rate of ~53.7 MHz. The output corresponds to a maximum pulse energy of 4.5 nJ, >5 times larger than that of a similar homemade mode-locked Tm laser with the LMA fibers replaced by single mode fibers, coinciding with theoretical prediction. The successful demonstration of our soliton mode-locked LMA fiber laser at $2~\mu \text{m}$ offers another strategy for high performance ultrafast fiber sources at mid-infrared region.

Low Threshold, High Efficiency Passively Mode-Locked Picosecond Tm,Ho:LiLuF4 Laser

We experimentally demonstrated a passively mode-locked picosecond Tm,Ho:LiLuF4 laser with low threshold and high efficiency. The stable continuous-wave (CW) mode-locked operation with 12ps pulse width is obtained by using a five-mirror cavity structure and semiconductor saturable absorber mirrors (SESAMs). The results indicate that the laser offers a mode-locked threshold power of 1.03W and maximum mode-locked output power of 350mW. The repetition rate of mode-locked pulse sequence is 98.04MHz, corresponding a maximum single pulse energy is 3.51nJ.

SWCNT-SA mode-locked Tm:LuYO3 ceramic laser delivering 8-optical-cycle pulses at 2.05 µm

Passive mode locking of a T m : L u Y O 3 ceramic laser in the 2 µm spectral region is demonstrated by employing a single-walled carbon nanotube-saturable absorber. Almost chirp-free pulses as short as 57 fs, i.e., 8 optical cycles are produced at a repetition rate of 72.6 MHz (63 mW average power). The corresponding optical spectrum centered at 2045 nm, exhibits a bandwidth of 80 nm, which corresponds to almost chirp-free pulses. To the best of our knowledge, the results represent the shortest pulses generated by mode-locked Tm solid-state lasers.

2 089 nm调Q锁模Tm,Ho∶CaYAlO4激光器

2 089 nm调Q锁模Tm,Ho∶CaYAlO4激光器