Diode End-pumped Tm Research Articles

Experimental and Modeled Output Characteristics of a Compact, Passively Q-Switched Tm:YLF Laser

We measure the output characteristics of a compact, laser diode end-pumped Tm:YLF laser, operated in continuous wave (CW) mode, or passively Q-switched (PQS) using various Cr2+:ZnS saturable absorbers. A numerical Finite-Difference Beam Propagation Method (FD-BPM) is developed and used to model the laser CW and pulsed performance. Good agreement between the experiment and simulated output is demonstrated. The 39 mm-long laser resonator utilizes a 20.2 mm-long Tm:YLF crystal, a 1908 nm volume Bragg grating (VBG) reflector to restrict the emission wavelength, and an intra-cavity negative lens to reduce the energy fluence in the saturable absorber. A laser utilizing a Cr2+:ZnS saturable absorber with 91.9% unsaturated transmission generates 9.8 mJ PQS pulses with 8.7 ns full-width-half-maximum (FWHM) pulse duration. Maximum average output powers of 6.1 W and 6.5 W are generated in PQS and CW operation, respectively.

LD end-pumped single-ended bonding Tm:LuAG laser

A diode end-pumped Tm:LuAG laser at room temperature was reported. The thermal lens effect of Tm:LuAG crystal was analyzed, the distribution of the light field and thermal field in the crystal was simulated moreover. In this paper, by using plane-concave resonator, the continuous 2 μm laser output with maximum output power of 10.8 W is obtained. The slope efficiency is 19.56% and the optical-to-optical conversion efficiency is 25.71%. The beam quality factors M2 are 1.24 and 1.28 in the x and y directions respectively.

Dual-wavelength mid-infrared CW and Q-switched laser in diode end-pumped Tm,Ho:GdYTaO4 crystal

Dual-wavelength continuous-wave and Q-switched lasers are demonstrated in a Tm,Ho:GdYTaO4 crystal under 790 nm laser diode end pumping for the first time to the best of our knowledge. The laser operates with a dual wavelength at 1949.677 nm and 2070 nm for continuous-wave with a spacing of about 120 nm. The maximum output power is 0.332 W with a pump power of 3 W. By using graphene as the saturable absorber, a passively Q-switched operation is performed with a dual-wavelength at 1950.323 nm and 2068.064 nm with a wavelength interval of about 118 nm. The maximum average output power of the Q-switched laser goes up to 200 mW with a minimum pulse duration of 1.2 µs and a maximum repetition rate of 34.72 kHz.

Measurement of output characteristics of Tm:YAG laser at 25–300 K

In this paper, output characteristics of a laser diode end-pumped Tm:YAG laser in a wide temperature range were investigated. In this laser system, a Tm:YAG crystal was cooled in a cryostat with liquid helium or liquid nitrogen as coolant. At the temperature of 88K, a maximum output power of 4.68W is achieved when the incident pump power is 8.9W, and the optical–optical conversion efficiency is 52.6%, with a slope efficiency of 56.1%. The dependence of the output characteristics of Tm:YAG on temperature was experimentally studied in the temperature range of 25–300K.

Low-cost low-threshold diode end-pumped Tm:YAG laser at 2.016 μm

We report a low-threshold continuous-wave Tm:YAG laser that can be excited near 785 nm with low-cost, single-mode AlGaAs laser diodes. Low-threshold operation was achieved using a tightly focused, astigmatically compensated x-cavity containing a 2-mm-thick Tm:YAG crystal with 5 % Tm3+ concentration. Two linearly polarized single-mode diodes operating at 785.8 nm were polarization coupled to end pump the resonator. With a 6 % output coupler, as high as 32 mW of output power could be obtained at 2016 nm with 184 mW of incident pump power. The output could be further tuned in the 1935–2035 nm range. Slope efficiency measurements indicated that cross-relaxation was very effective at this doping level. With a 2 % output coupler, lasing could be obtained with as low as 32.3 mW of pump power. In the limit of vanishing output coupling, the incident threshold pump power could be reduced to as low as 25 mW. To our knowledge, this is among the lowest lasing thresholds reported to date for continuous-wave, room-temperature thulium lasers.

Diode-pumped single-frequency Tm:GdVO4 laser at 1897.6 nm

A diode end-pumped Tm:GdVO4 laser at room temperature is reported. The maximal output power of single-frequency is as high as 34 mW by using two uncoated fused etalons, which are respectively 0.05 mm thick YAG and 1mm thick quartz. We obtained the single frequency Tm:GdVO4 laser at 1897.6 nm with the slope efficiency of 1.3%. The single-longitudinal-mode (SLM) laser can be used as a seed laser for coherent wind measurements and differential absorption LIDAR systems.

LD端面泵浦高重复频率全固态Tm,Ho:LuLF激光器

The characteristics of diode end-pumped Tm,Ho:LuLiF for continuous wave (CW) running and high pulse repetition frequency (PRF) Q-switched operation are illustrated. In the CW mode, 950-mW output power with a slope efficiency of 24% is obtained. In the Q-switched mode, output energy of 78 ?J under 10 kHz with a slope efficiency of 23% is achieved. The pulse stability, pulse width as a function of pump intensity, and spectral characteristics are also analyzed.

High efficiency 2.05-μm CW and AO Q-switched operation of diode end-pumped Tm,Ho:GdVO4 laser

The continuous-wave (CW) and acoustooptically (AO) Q-switched operation of a Tm (4 at %), Ho (0.4 at %):GdVO4 laser at a 2.05-μm wavelength were reported in this paper. The Tm,Ho:GdVO4 crystal was cooled by liquid nitrogen and end pumped by a 29.8-W fiber-coupled laser diode at 801 nm. A conversion efficiency of 41% and a slope efficiency of 46% were acquired with a continuous-wave output power of 12.2 W. An average power of 11.6 W was obtained at a pulse repetition frequency (PRF) of 10 kHz, corresponding to an optical-to-optical conversion efficiency of 38.9% and a slope efficiency of 41.4%. The energy per pulse of 1.8 mJ in 14 ns was achieved at 5 kHz with a peak power of 130 kW.

Diode-end-pumped CW Tm,Ho:YLF solid-state laser working at room temperature

The laser properties of laser diode end-pumped Tm and Ho co-doped lithium yttrium fluoride (YLF) laser are studied. The experiment of Tm,Ho:YLF laser is conducted for different output couplings, and the optimum output coupler transmission is 2% when the crystal is kept at room temperature. The distribution of far field intensity is measured by pin-hole scanning, the output laser is proved to be operating in the TEM00 mode, and the relation between thermal focal length and pump power is obtained. To achieve single frequency operation, two solid, uncoated fused silica etalons are used. The laser threshold pump power is 250 mW, and the maximum continuous wave single frequency output power is 118 mW at the pump power of 2.8 W. The single frequency laser may be used as a seed laser for either a larger oscillator or an amplifier.

High-power/high-brightness diode-pumped 1.9-/spl mu/m thulium and resonantly pumped 2.1-/spl mu/m holmium lasers

We report high power (>36 W) with beam propagation factor M/sup 2//spl sim/2 in a diode end-pumped Tm:LiYF/sub 4/ (Tm:YLF) laser generating output near the 1.91-/spl mu/m region. Using the 1.91-/spl mu/m emission and high brightness achieved with the Tm:YLF laser we resonantly end-pump the Holmium /sup 5/I/sub 7/ manifold in Ho:YAG and demonstrate /spl sim/19 W of continuous-wave (CW) output. The diode-to-Holmium optical to-optical conversion efficiency achieved is /spl sim/18%. Using a CW pumped and repetitively Q-switched configuration, the Tm:YLF pumped Ho:YAG laser achieves >16 W of output power with an M/sup 2//spl sim/1.48 at 15 kHz. A Q-switched frequency range of 9 to >50 kHz is also achieved.