Study of LD pumped Q-switched Nd:Y<Subscript>0.5</Subscript>Lu<Subscript>0.5</Subscript>VO<Subscript>4</Subscript> laser with acousto-optic modulator

A laser-diode (LD) pumped Q-switched Nd:Y_0.5Lu_0.5VO₄ crystal laser with an acousto-optic (AO) modulator is presented in this paper. The maximum continuous wave (CW) output power of 5.53 W is achieved at the incident pump power of 14.09 W with the transmission of 10% for the output coupler, resulting in an optical-to-optical conversion efficiency of 39.2%. For Q-switching operation, the shortest pulse width of 8.3 ns and the highest peak power of 259 kW are generated under the incident pump power of 14.09 W at 1 kHz.     

All-solid-state Nd:Gd<Subscript>0.18</Subscript>Y<Subscript>0.82</Subscript>VO<Subscript>4</Subscript>-LBO green laser at 532 nm

We report a continuous-wave (CW) coherent green radiation at 532 nm by intracavity frequency doubling generation of 1064 nm Nd:Gd_0.18Y_0.82VO₄ laser. With incident pump power of 18.2 W, output power of 1.08 W at 532 nm has been obtained using a 5 mm-long KTP crystal. The optical conversion efficiency was up to 5.9%. At the output power level of 1.08 W, the output stability is better than 5%. The beam quality M² values were equal to 1.26 and 1.12 in X and Y directions, respectively.     

Efficiency intracavity frequency-doubled Nd:Y<Subscript>0.36</Subscript>Gd<Subscript>0.64</Subscript>VO<Subscript>4</Subscript>-LBO green laser at 532 nm with direct pumping

We report an efficient laser emission on the 1064 nm ⁴ F _3/2 to ⁴ I _11/2 transition in mixed vanadate crystal Nd:Y_0.36Gd_0.64VO₄ under the pump with diode laser at 880 nm. Continuous wave (CW) 10.7 W output power at 1064 nm is obtained under 17.8 W of incident pump power; the slope efficiency with respect to the incident pump power was 71.2%. Moreover, intracavity frequency doubling with LiB₃O₅ (LBO) nonlinear crystal yielded 4.6 W of green light at 532 nm. An optical-to-optical efficiency with respect to the incident pump power was 25.8%.     

Diode-pumped Nd:LuVO<Subscript>4</Subscript>-LBO green laser at 533 nm

We report a continuous-wave (CW) coherent green radiation at 533 nm by intracavity frequency doubling generation of 1066 nm Nd:LuVO₄ laser. With incident pump power of 18.2 W, output power of 4.3 W at 533 nm has been obtained using a 5 mm-long LBO crystal. The optical conversion efficiency was up to 23.6%. At the output power level of 4.3 W, the output stability is better than 3%. The beam quality M² values were equal to 1.13 and 1.21 in X and Y directions, respectively.     

Performance comparisons of passively Q-switched intracavity-frequency-doubled Nd:Gd<Subscript>0.19</Subscript>Y<Subscript>0.81</Subscript>VO<Subscript>4</Subscript> and Nd:Gd<Subscript>0.83</Subscript>Y<Subscript>0.17</Subscript>VO<Subscript>4</Subscript> lasers at 671 nm

Performance comparisons of laser-diode pumped passively Q-switched intracavity-frequency-doubled Nd:Gd_0.19Y_0.81VO₄ and Nd:Gd_0.83Y_0.17VO₄ lasers at 671 nm are demonstrated for the first time to our knowledge. KTP crystal is used as the frequency doubling material and V:YAG crystal as the saturable absorber with initial transmission of 89%. The dependences of average output power, pulse width, pulse repetition rate, single-pulse energy and peak power on incident pump power are measured and contrasted. The experimental results show that, Nd:Gd_0.83Y_0.17VO₄ laser has more excellent properties than Nd:Gd_0.19Y_0.81VO₄ laser at 671 nm.     

All solid-state continuous-wave intracavity frequency-doubled Nd:LuVO<Subscript>4</Subscript>-LBO red laser at 671.5 nm

We report for the first time a efficient compact red laser at 671.5 nm generation by intracavity frequency doubling of a continuous wave laser operation of a diode direct pumped Nd:LuVO₄ laser on the ⁴ F _3/2 → ⁴ I _13/2 transition at 1343 nm. An LBO crystal, cut for critical type I phase matching at room temperature is used for second harmonic generation of the laser. At an absorbed pump power of 16.2 W, as high as 4.3 W of continuous wave output power at 671.5 nm is achieved with 10-mm-long LBO. Comparative results obtained for the pump with diode laser at 808 nm, into the highly-absorbing ⁴ F _5/2 level, are given in order to prove the advantages of the 880 nm wavelength pumping.     

Characteristics of diode-pumped dual-loss-modulated Q-switched and mode-locked Nd:Lu<Subscript>0.15</Subscript>Y<Subscript>0.85</Subscript>VO<Subscript>4</Subscript> laser

A diode-pumped dual-loss-modulated Q-switched and mode-locked (QML) Nd:Lu_0.15Y_0.85VO₄ laser with acousto-optic (AO) modulator and Cr⁴⁺:YAG saturable absorber is presented. The stable QML laser pulse with high peak power and complete modulation depth has been obtained. The QML laser characteristics such as the pulse width, single-pulse energy etc. have been measured for different small-signal transmissions (T ₀) of Cr⁴⁺:YAG, different reflectivity (R) of output coupler and modulation frequencies of the AO modulator (f _p ). The results show that the pulse energy increases with decreasing f _p and increasing T ₀, while the pulse width decreases with decreasing f _p and increasing T ₀. At f _p = 10 kHz, R = 90%, and T ₀ = 91%, the highest pulse energy and peak power of mode-locked pulses is obtained.     

Diode-pumped Q-switched Nd:Y<Subscript>0.5</Subscript>Lu<Subscript>0.5</Subscript>VO<Subscript>4</Subscript> laser double-modulated with an acousto-optic modulator and Cr<Superscript>4+</Superscript>:YAG saturable absorber

A diode pumped Nd:Y_0.5Lu_0.5VO₄ pulse laser modulated with an acousto-optic (AO) Q-switcher and Cr⁴⁺:YAG saturable absorber is first demonstrated in this paper. The laser is shown to generate shorter pulse width than AO Q-switched laser alone, and have a higher peak power and single pulse energy than passively Q-switched laser with only Cr⁴⁺:YAG. A laser pulse width of 6.16 ns and a peak power of about 43.83 kW are achieved at the incident pumping power of 14.09 W.     

All-solid-state CW Nd:GdVO<Subscript>4</Subscript>-LBO red laser under direct 912 nm pumping

We report a red laser at 670.5 nm generation by intracavity frequency doubling of a continuous wave (CW) laser operation of a 1341 nm Nd:GdVO₄ laser under in-band diode pumping at 912 nm. An LBO crystal, cut for critical type I phase matching is used for second harmonic generation of the laser. At an incident pump power of 8.9 W, as high as 347 mW of CW output power at 670.5 nm is achieved. The fluctuation of the red output power was better than 3.7% in the given 30 min, and the beam quality factor M ² is 1.65.     

Passively Q-switched laser performance of a diode-pump mixed Nd:Lu<Subscript>0.15</Subscript>Y<Subscript>0.85</Subscript>VO<Subscript>4</Subscript> crystal

A diode-pumped passively Q-switched Nd:Lu_0.15Y_0.85VO₄ laser with a GaAs output coupler is demonstrated. By using a mixed crystal Nd:Lu_0.15Y_0.85VO₄ as laser medium, the passively Q-switched laser can generate shorter pulse width with higher peak power in comparison with the passively Q-switched Nd:LuVO₄ or Nd:YVO₄ lasers under the same laser cavity. At the incident pump power 11.9 W, the minimum pulse width of 3.23 ns and the maximum peak power 1.67 kW can be obtained. The average output power and the pulse repetition rate of the laser are also measured. The experimental results show that the mixed crystal is a promising laser medium for shorter Q-switched pulse with higher peak power.     

Diode-pumped passively Q-switched and mode-locked Nd:Lu<Subscript>0.15</Subscript>Y<Subscript>0.85</Subscript>VO<Subscript>4</Subscript> laser with a GaAs saturable absorber

By using a-cut Nd:Lu_0.15Y_0.85VO₄ mixed crystal as laser gain medium, a diode-pumped passively Q-switched and mode-locked (QML) laser with a GaAs saturable absorber in a Z-type folded cavity is demonstrated for the first time. The Q-switched mode-locked laser pulses with about 90% modulation depth are obtained as long as the pump power reached the oscillation threshold. The repetition rate of the passively Q-switched pulse envelope ranges from 50 to 186 kHz as the pump power increases from 0.915 to 6.520 W. Under an incident pump power of 6.52 W, the QML pulses with the largest average output power of 694 mW, the shortest pulse width of 200 ns and the highest pulse energy of 3.73 μJ are obtained. The mode-locked pulse width inside the Q-switched envelope is estimated to be about 275 ps. The experimental results show that Nd:Lu_0.15Y_0.85VO₄ is a promising mixed crystal for QML laser.     

All-solid-state CW Nd:LuVO<Subscript>4</Subscript>-LBO laser at 533 nm under direct 888 nm pumping

We report an efficient laser emission on the 1066 nm ⁴ F _3/2 to ⁴ I _11/2 transition in Nd:LuVO₄ under the pump with diode laser at 888 nm. Continuous wave (CW) 11.2 W output power at 1066 nm is obtained under 18.3 W of incident pump power; the slope efficiency with respect to the incident pump power was 71.9%. Moreover, intracavity frequency doubling with LiB₃O₅ (LBO) nonlinear crystal yielded 4.2 W of green light at 533 nm. An optical-to-optical efficiency with respect to the incident pump power was 23.0%.     

Experimental study on doubly QML Nd:Lu<Subscript>0.15</Subscript>Y<Subscript>0.85</Subscript>VO<Subscript>4</Subscript> laser with AO modulator and central SESAM

By using double-mixed crystal Nd:Lu_0.15Y_0.85VO₄ as laser medium, a diode-pumped doubly Q-switched and mode-locked (QML) Nd:Lu_0.15Y_0.85VO₄ laser with acousto-optic (AO) modulator and central semiconductor saturable absorption mirror (SESAM) is realized for the first time. The Q-switched envelope modulation depth is nearly 100%.The average output power and the pulse width of the Q-switched envelope etc. for different AO modulator repetition rates have been measured. The experimental result show that Nd:Lu_0.15Y_0.85VO₄ crystal is an excellent laser medium for doubly QML lasers.     

Quasi-three-level laser operation of Nd:Y<Subscript>0.53</Subscript>Gd<Subscript>0.47</Subscript>VO<Subscript>4</Subscript> mixed vanadate crystal oscillating at 913 nm

Efficient continuous-wave (CW) laser operation on the ⁴ F _3/2 → ⁴ I _9/2 transition of Nd:Y_0.53Gd_0.47VO₄, a mixed vanadate crystal, is demonstrated at room temperature employing a compact plano-concave resonator, generating a polarized output power of 0.39 W at 913.2 nm with 2.85 W of pump power absorbed, the optical-to-optical and slope efficiencies being 14 and 25%, respectively.     

High efficiency 1341 nm Nd:GdVO<Subscript>4</Subscript> laser in-band pumped at 912 nm

A high-efficiency 1341 nm Nd:GdVO₄ laser in-band pumped at 912 nm is demonstrated for the first time. Using an all-solid-state Nd:GdVO₄ laser operating at 912 nm as pump source, 542 mW output was obtained with 1.14 W absorbed pump power. The slope efficiency with respect to the absorbed pump power was 56.6%, and the fluctuation of the output power was better than 2.6% in the given 30 min. The beam quality factor M ₂ is 1.15.     

Diode-pumped Nd:YVO<Subscript>4</Subscript> intracavity-doubled red laser at 693 nm

It is reported that efficient continuous-wave (CW) red laser generation at 693 nm in a LBO crystal at type-I phase matching direction performed with a diode-pumped Nd:YVO₄ laser. With incident pump power of 18.2 W, output power of 278 mW at 693 nm has been obtained using a 10 mm-long LBO crystal. At the output power level of 278 mW, the output stability is better than 2.9%.     

Crystal growth,spectroscopic characterization and laser performance of Nd:Lu<Subscript>0.33</Subscript>Y<Subscript>0.36</Subscript>Gd<Subscript>0.3</Subscript>VO<Subscript>4</Subscript> crystal

A new three-matrix mixed vanadate crystal Nd:Lu_0.33Y_0.36Gd_0.3VO₄ (Nd:LuYGdVO₄) crystal was grown by the Czochralski method. Room temperature absorption and fluorescence spectra of the Nd:LuYGdVO₄ crystals were measured and the spectroscopic parameters were calculated by the Judd-Ofelt theory. The intensity parameters of the Nd:LuYGdVO₄ crystal were Ω₂ = 9.736 × 10⁻²⁰ cm², Ω₄ = 4.179 × 10⁻²⁰ cm², Ω₆ = 8.020 × 10⁻²⁰ cm² and the stimulate emission cross section was 5.3 × 10⁻¹⁹ cm². Diodepumped actively Q-switched and passively Q-switched Nd:LuYGdVO₄ and Nd:Lu_0.14Y_0.86VO₄ lasers at 1.06 μm were demonstrated. The results indicate that, for both actively and passively Q-switched lasers, the Nd:LuYGdVO₄ lasers can generate shorter pulse width with higher peak power than the Nd:Lu_0.14Y_0.86VO₄ lasers at the same cavity conditions.     

High efficiency 1341 nm Nd:GdVO<Subscript>4</Subscript> bounce laser in-band pumped at 879 nm

A high-efficiency Nd:GdVO₄ bounce laser in-band pumped at 879 nm is demonstrated for the first time. From a side-pumped Nd:GdVO₄ crystal, 8.2 W output was obtained with 18.5 W absorbed pump power. Corresponding slope efficiency with respect to the absorbed pump power was 51.4%, and the beam quality factor M2 is 1.13 and 1.15 for tangential direction and sagittal direction, respectively. Effects of crystal’s doping concentration and temperature on laser power and conversion efficiency were also investigated.     

All-solid-state CW intracavity frequency-doubling Nd:Lu<Subscript>2</Subscript>O<Subscript>3</Subscript>/LBO red laser at 679.5 nm

We report an efficient intracavity second-harmonic generation (SHG) at 1359 nm in a non-linear optical crystal, LiB₃O₅ (LBO), performed with a diode end pumped continuous-wave (cw) Nd:Lu₂O₃ laser. In the case of a laser with a Nd:Lu₂O₃ crystal frequency-doubled with a LBO crystal cut for type I frequency doubling. A cw SHG output power of 462 mW has been obtained using a 10 mm long LBO crystal. The red power stability was 3.4% in 4 h.     

Diode-pumped Nd:YVO<Subscript>4</Subscript>-LBO laser at 544 nm based on intracavity sum frequency generation

A dual-wavelength continuous-wave (CW) diode-pumped Nd:YVO₄ laser that generates simultaneous laser action at the wavelengths 914 and 1342 nm is demonstrated. A total dual-wavelength output power of 1.79 W was achieved at the incident pump power of 18.2 W. Furthermore, intracavity sum-frequency mixing at 914 and 1342 nm was then realized in a LBO crystal to reach the yellow-green range. We obtained a total CW output power of 212 mW at 544 nm.