SrF2 Laser Research Articles

Room-temperature high-power laser emission of erbium-doped fluorite crystals at 2.8 µm.

We report on a high-power continuous-wave (CW) laser at 2.8 µm employing erbium (Er)-doped fluorite crystals as gain materials. With an optimized Er3+ ion concentration, thin "slab" geometry of the sample matching with the tailored pump beam profile and compensated negative thermal lens using a pair of concave mirrors cavity configuration, a highest power of 14.5 W is achieved from a dual-end-pumped Er:CaF2 laser, which, to the best of our knowledge, presents the record power from the room-temperature Er-bulk lasers in the 3-µm spectral range. In addition, 8.05 W output power is obtained from the Er:SrF2 laser with an RMS power stability of 0.35%. This work indicates that Er-doped fluorite crystals with large-scale available fabrication are promising candidates for high-power laser emission at ∼3 µm.

SnS2 as a Saturable Absorber for Mid-Infrared Q-Switched Er:SrF2 Laser.

Two-dimensional (2D) materials own unique band structures and excellent optoelectronic properties and have attracted wide attention in photonics. Tin disulfide (SnS2), a member of group IV-VI transition metal dichalcogenides (TMDs), possesses good environmental optimization, oxidation resistance, and thermal stability, making it more competitive in application. By using the intensity-dependent transmission experiment, the saturable absorption properties of the SnS2 nanosheet nearly at 3 μm waveband were characterized by a high modulation depth of 32.26%. Therefore, a few-layer SnS2 was used as a saturable absorber (SA) for a bulk Er:SrF2 laser to research its optical properties. When the average output power was 140 mW, the passively Q-switched laser achieved the shortest pulse width at 480 ns, the optimal single pulse energy at 3.78 µJ, and the highest peak power at 7.88 W. The results of the passively Q-switched laser revealed that few-layer SnS2 had an admirable non-linear optical response at near 3 μm mid-infrared solid-state laser.

Sub-50 fs diode-pumped SESAM mode-locked Yb:SrF2 laser.

We report on sub-50 fs pulse generation from a passively mode-locked Yb:SrF2 laser pumped with a spatially single-mode, fiber-coupled laser diode at 976 nm. In the continuous-wave regime, the Yb:SrF2 laser generated a maximum output power of 704 mW at 1048 nm with a threshold of 64 mW and a slope efficiency of 77.2%. A continuous wavelength tuning across 89 nm (1006 - 1095 nm) was achieved with a Lyot filter. By implementing a SEmiconductor Saturable Absorber Mirror (SESAM) for initiating and sustaining the mode-locked operation, soliton pulses as short as 49 fs were generated at 1057 nm with an average output power of 117 mW at a pulse repetition rate of ∼75.9 MHz. The maximum average output power of the mode-locked Yb:SrF2 laser was scaled up to 313 mW for slightly longer pulses of 70 fs at 1049.4 nm, corresponding to a peak power of 51.9 kW and an optical efficiency of 34.7%.

Mid-Infrared Dual-Wavelength Passively Q-Switched Er: SrF2 Laser by CsPbCl3 Quantum Dots Absorber

A passively Q-switched compact dual-wavelength Er: SrF2 laser, operating at a 2729.73 nm and 2747.2 nm wavelength, was demonstrated by utilizing CsPbCl3 quantum dots (QDs) as a saturable absorber (SA). The maximum average output power with the shortest duration of 510 ns and a repetition rate of 45 kHz was achieved at 190 mW, and the corresponding maximum single pulse energy and the peak power were 73.69 μJ and 141.7 W, respectively. The results present an efficient dual-wavelength laser source, and the halogen perovskite quantum dot has the potential to be employed as an excellent saturable absorber in mid-infrared pulsed solid-state lasers.

Tb,Y:SrF2 crystal for efficient laser operation in the visible spectral region.

A Tb,Y:SrF2 crystal with high optical quality is grown using the temperature gradient technique. The spectroscopic and laser properties of the crystal in the visible spectral region are studied. A fluorescence lifetime of 5.6 ms is measured from the crystal, which is beneficial for laser operation with a low threshold. A continuous-wave Tb,Y:SrF2 laser delivers an output power of 259 mW at 545 nm, with a slope efficiency of 35.2%. To the best of the authors' knowledge, this is the first report on a Tb-doped SrF2 laser and represents the highest output power for visible alkaline-earth fluoride lasers. The limitations for power scaling are discussed.

Spectroscopic and laser properties of a broadly tunable diode-pumped Tm3+ :CaF2–SrF2 laser

The spectroscopic and laser properties of mixed fluoride Tm:CaF2–SrF2 crystals were investigated. The 1.9 m radiation was obtained in two samples with Tm3+ ion doping concentrations of 1.0 mol% and 2.0 mol% under laser diode pumping at 763 nm. The highest slope efficiency of 32.5% and the widest laser tuning range of 232 nm (1761–1993 nm) were demonstrated with the 1%-doped sample. The maximal output power amplitude of 3.4 W at 1902 nm for an absorbed pump power amplitude of 13.8 W was demonstrated with the 2%-doped sample.

Heat‐driven Tailored for Eliminating Nd3+ Re‐clusters in Nd3+,Gd3+‐codoped SrF2 Laser Ceramic

AbstractTransparent Nd3+,Gd3+‐codoped SrF2 laser ceramic was fabricated by a single‐crystal ceramization (SCC) technique, and the fluorescence properties were also characterized. The results indicated that the SCC process would lead to reducing fluorescence properties of ceramic by re‐clustering small amount of Nd3+ ions. In this study, the re‐clustering of Nd3+ ions were addressed by a simple thermal drive‐induced grains regrowth (TDIGR) treatment. The properties of the Nd3+,Gd3+‐codoped SrF2 laser ceramic undergo the TDIGR were improved and close to precursor Nd3+, Gd3+‐codoped SrF2 single crystal. Meanwhile, the transmittance of ceramic (Taverage@400‐1400nm ~ 92%) was hardly affected by the TDIGR treatment. Therefore, we have reasons to believe that the combination of SCC and TDIGR is a suitable approach to obtain high optical quality neodymium, buffer ion‐codoped alkaline‐earth fluoride (Nd3+,B3+‐codoped MF2) laser ceramics.

Mid-infrared Er:CaF2–SrF2 bulk laser Q-switched by MXene Ti3C2Tx absorber

We report a diode-pumped passively Q-switched Er:CaF2–SrF2 laser at 2.73 μm with MXene Ti3C2Tx as a saturable absorber (SA). A maximum average output power of the pulsed laser was measured at 286 mW, with a shortest duration of 814 ns and a repetition rate of 45.3 kHz. The corresponding single-pulse energy and peak power were calculated to be 6.32 μJ and 7.76 W, respectively. The results suggest the promising potential of MXene as an efficient SA for short pulse lasers in the mid-infrared spectral band.

WS2 Passively Q-switched Er:SrF2 Laser at ~3 µm

A few-layer tungsten disulfide (WS2) nanosheet film on a YAG substrate was fabricated and used as saturable absorber in a passively Q-switched Er:SrF2 laser operating at 2.79 µm. Under an absorbed power of 2.42 W, a stable Q-switched laser operation was realized with an average output power of 428 mW and a pulse duration of 679 ns at a repetition rate of 38 kHz, corresponding to a pulse energy of 11.26 µJ.

Bismuth nanosheets as a Q-switcher for a mid-infrared erbium-doped SrF2 laser

Bismuth nanosheets (Bi-NSs) were successfully prepared and employed as saturable absorbers to generate a diode-pumped dual-wavelength Er3+:SrF2 laser in the mid-infrared region. Q-switched pulses with a maximum output power of 0.226 W were obtained at an absorbed pump power of 1.97 W. A repetition rate of 56.20 kHz and a minimum pulse duration of 980 ns were achieved. To the best of our knowledge, we present the first application of Bi-NSs in a mid-infrared all-solid-state laser. The results prove that Bi-NSs may be applied as an optical modulator in mid-infrared photonic devices or as a mode-locker and Q-switcher.

Continuous wave and ReS2 passively Q-switched Er : SrF2 laser at ∼3 μm.

We report on an efficient Er:SrF2 laser at 2.79μm. A continuous wave output power of 1.06W was obtained with a slope efficiency of 41%, significantly exceeding the Stokes efficiency of 35%. Stable Q-switched laser operation was realized by using an ReS2 saturable absorber, generating an average output power of 0.58W with a pulse duration of 508ns at a repetition rate of 49kHz, corresponding to a pulse energy of 12.1μJ.

Diode-pumped Er:SrF2 laser tunable at 27 μm

The tunability of Er:SrF2 laser was investigated at room temperature. Under pulsed laser diode pumping, the mid-infrared (2.75 μm) radiation was obtained with a maximal reached output power amplitude of 1.3 W and a slope efficiency up to 9.2 %. Laser tunability was reached using a MgF2 birefringent filter and the tuning range of 123 nm (2690 nm – 2813 nm) with Er:SrF2 was obtained.

Highly-efficient mid-infrared CW laser operation in a lightly-doped 3 at.% Er:SrF2 single crystal.

3 at.% Er:SrF2 laser crystals with high optical quality were successfully grown using the temperature gradient technique (TGT). The intense mid-infrared emission was observed around 2.7 μm with excitation by a 970 nm LD. Based on the Judd-Ofelt theory, the emission cross-sections of the 4I13/2-4I11/2 transition were calculated by using the Fuchtbauer-Ladenburg (FL) method. Efficient continuous-wave laser operation at 2.8 µm was achieved with the lightly-doped 3 at.% Er:SrF2 crystal pumped by a 970 nm laser diode. The laser output power reached up to 1.06 W with a maximum slope efficiency of 26%.

Passively mode-locked 354–1200 fs and continuous-wave 1044–1081 nm tunable operation of diode-pumped Nd,La:SrF2 laser

The fundamental spectroscopic properties of four Nd,La:SrF2 crystals with different and concentrations are described. The laser generation was successfully achieved with all crystals; the best results with the at.% , 8 at.% : are presented. The laser output wavelength tuning properties were investigated, and were found to have continuous tuning range over 37 nm from 1044 to 1081 nm. Two different saturable absorbers were succesfully tested for the passively mode-locked regime, and the intracavity dispersion compensation influence was studied. In the optimal set-up, a continuously mode-locked train of pulses as short as 354 fs was generated at the repetition rate of MHz. The laser central wavelength was ∼1059 nm and the overall output power reached 300 mW in two beams with absorbed pump power of less than W.

退火处理对Nd,Y∶SrF2激光晶体结构缺陷的影响

退火处理对Nd,Y∶SrF₂激光晶体结构缺陷的影响

Dual-wavelength Q-switched Er:SrF2 laser with a black phosphorus absorber in the mid-infrared region.

An efficient Er:SrF2 crystal, lightly Er-doped to a concentration of 4at.%, was successfully grown by the traditional Bridgman method and displayed excellent spectral properties. A diode-end-pumped passively Q-switched dual-wavelength laser, operating at 2.79 μm wavelength, was demonstrated with this crystal by using black phosphorus as the saturable absorber (BP-SA). In the compact passively Q-switched Er:SrF2 laser, the maximum average output power of 180 mW was achieved at an absorbed pump power of 2.47 W, with a pulse duration of 702 ns and a repetition rate of 77.03 kHz. To the best of our knowledge, this is the first reported application of BP-SA to dual-wavelength pulse laser operation in the mid-infrared region.

Tunable Nd, La:SrF2 laser and passively Q-switched operation based on gold nanobipyramids saturable absorber**Project supported by the National Natural Science Foundation of China (Grant Nos. 61475089, 51432007, and 61422511).

A novel Nd, La:SrF2 disordered crystal is prepared, and its continuous-wave wavelength tuning operation is performed for the first time. Employing a surface plasmon resonance (SPR) based gold nanobipyramids (G-NBPs) saturable absorber, we obtain a compact diode-pumped passively Q-switched Nd, La:SrF2 laser. The stable Q-switched pulse operates with the shortest pulse duration of and the maximum repetition rate of 41 kHz. The corresponding single pulse energy is . The results indicate that G-NBPs could be a promising saturable absorber applied to the diode-pumped solid state lasers (DPSSLs).

Generation of sub-100 fs pulses from mode-locked Nd,Y:SrF2 laser with enhancing SPM

A mode-locked laser using Nd,Y:SrF2 crystal as the gain medium is presented in this letter. By special design of the cavity for enhancing the self-phase modulation effect, femtosecond mode-locking with 97 fs pulse duration and 13.2 nm spectral width centered at 1061 nm is obtained at a repetition rate of 96 MHz. The average output power is 102 mW under 925 mW pump power, corresponding to the optical-to-optical efficiency of 11%. To the best of our knowledge, these are the first sub-100 fs pulses generated from a mode-locked Nd doped crystal laser.

Single-walled carbon nanotube saturable absorber for a diode-pumped passively mode-locked Nd,Y:SrF2 laser

A reflective single-walled carbon nanotube as saturable absorber has been firstly adopted to a passively mode-locked Nd,Y:SrF2 crystal. Without any dispersion compensation, the stably mode-locked laser delivers pulses with pulse width as short as 1.7ps, repetition rate of 107.8MHz and center wavelength of 1056nm. The oscillator produces maximum average output power of 319mW corresponding with a high slope efficiency of 20.2%. The single pulse energy and the peak power are 2.96nJ and 1.74kW, respectively. The experimental results show that single-walled carbon nanotube is an excellent saturable absorber for mode-locked lasers.

Diode-pumped mode-locked operation of a Nd,Y-codoped:SrF2 Laser

The continuously mode-locked operation of a novel Nd,Y:SrF2 laser pumped by the low power 796 nm multimode laser diode and mode-locked using a semiconductor saturable absorber mirror is demonstrated. The continuous train of pulses with the total output power of 70 mW and the pulse duration of 0.9 ps with the repetition rate of 142 MHz at the wavelength of 1.06 μm was generated from the resonator without dispersion compensation giving a good potential for generation of femtosecond pulses from a diode pumped system.