Diode-pumped short pulse passively Q-switched 912 nm Nd:GdVO<Subscript>4</Subscript>/Cr:YAG laser at high repetition rate operation

A diode-end-pumped passively Q-switched 912 nm Nd:GdVO₄/Cr:YAG laser is demonstrated for the first time. In a concave-piano cavity, pulsed 912 nm laser performance is investigated using two kinds of Cr:YAG crystal with different unsaturated transmission (T _U) of 95% and 90% at 912 nm as the saturable absorbers. When the T _U = 90% Cr:YAG is used, as much as 2.6 W average output power for short pulsed 912 nm laser is achieved at an absorbed pump power of 34.0 W, corresponding to an optical efficiency of 7.6% and a slope efficiency of 20.3%. Moreover, 10.5 ns duration pulses and up to 2.3 kW peak power is obtained at the repetition rate around 81.6 kHz.     

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.     

LD-end-pumped Nd:YAP laser operating at 1341.4 nm and doubling of its frequency

We report an LD-end-pumped linearly-polarized continuous-wave (CW) Nd:YAP laser operating at 1341.4 nm. Making use of the plane-concave resonator (T = 2.4%) and the plane-plane resonator (T = 2.6%), we obtain linearly-polarized laser radiation at 1341.4 nm with a power of 3.15 and 2.86 W and corresponding optical slope efficiency of 18.4 and 17.5%, respectively. The effect of the laser oscillation mode on the output is analyzed. An experiment on the intra-cavity frequency doubling with an LBO crystal has been performed, and a laser power of 431 mW in one direction at 670.7 nm was obtained.     

Dual-Wavelength and Passively Q-Switched Nd :GdVO4 Lasers Operated at 1.34 μm Under 880 nm Diode Pumping

We report continuous-wave (CW) and passively Q-switched Nd :GdVO₄ lasers on ⁴F_3/2 → ⁴I_13/2 transition directly pumped by an 880 nm diode laser. A widely investigated Nd :GdVO₄ laser at about 1341 nm is operated with a maximum output power of 5.23 W and a slope efficiency of about 30.6%. Using an etalon for wavelength selection, we realize laser emission at about 1344 nm, for the first time to our knowledge, in a Nd :GdVO₄ laser, with a maximum output power of 4.19 W and a slope efficiency of 20.1%. Moreover, we achieve simultaneous dual-wavelength lasing at 1341 and 1344 nm with a maximum output power of 2.27 W and a slope efficiency of 13.5%, respectively. Using V³⁺ :YAG as a saturable absorber, stable Q switching is obtained at about 1341 nm with a maximum average output power of 1.15 W. The pulse width is 52.8 ns at a repetition rate of 279.8 kHz.

     

High efficiency continuous-wave single-frequency Nd:YVO<Subscript>4</Subscript> ring laser under diode pumping at 880 nm

An efficient single-frequency continuous-wave Nd:YVO₄ ring laser pumped at 880 nm is presented. With compact four-mirror ring cavity and optical isolator, we obtained an output power of 14.56 W at 1064 nm, corresponding to a slope efficiency of 61.7% and an optical-to-optical efficiency of 58.4% with respect to the absorbed pump power. The stability of the output power was better than ±0.5% over two hours. At the same time, a beam quality factor of M ²≈1.2 was measured and the line width of the longitudinal mode was about 25 MHz. To the best of our knowledge, this is the highest slope efficiency and optical-to-optical efficiency in single-frequency Nd:YVO₄ ring laser.     

LD泵浦Nd:YAG/LBO结构660 nm红光激光器

采用国产LD泵浦Nd:YAG晶体,通过谐振腔镜的膜系选择获得了Nd³⁺离子中波长为1319 nm的受激辐射振荡,首次用I类临界位相匹配LBO进行腔内倍频,实现了660 nm红色激光的高效倍频输出.当泵浦注入功率为800 mW时,660 nm激光基横模(TEM₀₀)输出功率为46 mW,光光转换效率高达5.75%.     

Diode-pumped passively Q-switched Nd:YAG ceramic laser at 1319 nm with Co2+:LaMgAl11O19 crystal as the saturable absorber

The performance of a LD-pumped passively Q-switched Nd:YAG ceramic laser at 1319 nm with a Co:LMA saturable absorber was demonstrated for the first time to the best of our knowledge. The average output power of 1.58 W was obtained at the pump power of 23.3 W, corresponding to the optical conversion efficiency of 6.78% and slope efficiency of 11.2%. The minimum pulse width was 23 ns with the pulse repetition rate of 83 kHz, which was attained with a T = 1% output coupler at the pump power of 23.3 W.     

High efficient continuous wave operation of diode-double-passing-pumped Tm:YAP laser

A high efficient continuous wave diode-pumped Tm:YAP laser at room temperature was presented in this paper. Tm:YAP crystal with doped concentration of 4 at % was c-cut and had a cross section of 3 × 3 mm² and length of 5 mm. Using double-passing-pumped cavity structure, under the pump power was 25.5 W, the highest output power reached 8.5 W by use of 10% output coupling, corresponding to optical conversion efficiency was 33.3% and the slope efficiency was 44.5%. The laser wavelength was 1936 nm with FWHM of 4 nm.     

Continuous wave operation of singly-doped Ho:LSO laser at room temperature

We present the room-temperature continuous-wave Ho:LSO laser single-pass-end-pumped by a diode-pumped Tm:YLF laser at 1.91 μm in this paper. Under different output couplers of 2.4, 5.0, and 14.0%, the laser output power and output spectrum of Ho:LSO laser operating at room temperature are investigated. The output wavelength of Ho:LSO laser was centered at 2106.5 nm with linewidth (FWHM) of about 3.2 nm. With T = 5.0%, the maximum output power of 2.4 W was achieved under the absorbed pump power of 11.1 W, corresponding to a slope efficiency of 38.0%.     

A high efficiency Ho:YAlO<Subscript>3</Subscript> laser pumped by Tm:YLF laser with a Volume Bragg Grating

We report a CW Ho:YAlO₃ (Ho:YAP) laser at room temperature pumped by a Tm:YLF laser with a Volume Bragg Grating (VBG) instead of the conventional mirror. The Ho:YAP laser operated at 2117.9 nm with output power 9.12 W. The optical-to-optical conversion efficiency is 60.4% and slope efficiency is 71.2%. The Ho:YAP output wavelength is centered at 2117.9 nm with bandwidth of about 1 nm. The beam quality factor is M ² ∼ 1.29 measured by the traveling knife-edge method.     

Passively Q-switched <Emphasis Type="Italic">a</Emphasis>-cut Nd:YVO<Subscript>4</Subscript> self-Raman laser

A passively Q-switched a-cut Nd:YVO₄ self-stimulating Raman laser using a Cr:YAG saturable absorber has been demonstrated for the first time. The maximum average output power of the self-Raman laser at 1176 nm is 347 mW at the incident pump power of 10 W with a pulse repetition frequency (PRF) of 66 kHz. The pulse width, pulse energy of the 1176 nm are found to be 10 ns and 5.6 μJ. The conversion efficiency from diode laser input power to Raman output power is 3.47%.     

Diode-end-pumped passively Q-switched 1319 nm Nd:YAG ceramic laser with a V<Superscript>3+</Superscript>:YAG saturable absorber

The performance of a LD-end-pumped passively Q-switched Nd:YAG ceramic laser at 1319 nm with a V³⁺:YAG saturable absorber was demonstrated for the first time to the best of our knowledge. The average output power of 1.8 W was obtained under the pump power of 23.7 W, corresponding to the optical conversion efficiency of 7.8% and slope efficiency of 9%. The minimum pulse width was 128 ns with the pulse repetition rate of 230 kHz, which was attained with a T = 2.8% output coupler at the pump power of 23.7 W.     

885 nm LD end-pumped 22.7 W high beam quality electro-optical Q-switched Nd:YAG laser

We report an 885 nm laser diode (LD) end-pumped high beam quality (M _x ² = 1.322, M _y ² = 1.235) electro-optical Q-switched Nd:YAG laser with TEM₀₀-mode output for the first time. At the absorbed pump power of 59.5 W, a 22.7 W 1064 nm laser was achieved at 10 kHz repetition rate with optical-to-optical efficiency of 38.1%. The maximum pulse energy and shortest pulse width were 5.1 mJ and 14.5 ns at 2 kHz repetition rate, and the calculated peak power was 352 kW.     

Laser performance of grown-together YVO4/Nd:YVO4 composite crystal at continuous-wave 914 nm

We demonstrated a diode-end-pumped continuous-wave 914 nm laser using a novel grown-together YVO₄/Nd:YVO₄ crystal for the first time. A maximum output power at 914 nm of 7.5 W with an optical-optical efficiency of 16.3% and a slope efficiency of 24.3% was obtained when the incident pump power was 46.2 W. The beam quality factor M ² was 3.2 at the output power of 6.0 W. The quality and specification of the grown-together composite YVO₄/Nd:YVO₄ crystal should be improved. Meanwhile, energy-transfer upconversion spectrum of the composite YVO₄/Nd:YVO₄ crystal laser was also investigated.     

Diode-pumped continuous-wave Nd:YLF laser at 1313 nm

We present an efficiency Nd:LiYF₄ (Nd:YLF) laser operating at 1313 nm pumped directly into the emitting level ⁴ F _3/2. At the incident pump power of 10.3 W, as high as 3.1 W of continuous-wave output power at 1313 nm is achieved. The slope efficiency with respect to the incident pump power was 36.1%. To the best of our knowledge, this is the first demonstration of such a laser system. Comparative results obtained for the pump with diode laser at 806 nm, into the highly absorbing ⁴ F _5/2 level, are given in order to prove the advantages of the 880 nm wavelength pumping.     

High-efficiency 17 W, 80 MHz repetition rate,passively mode-locked TEM<Subscript>00</Subscript> Nd:YAG oscillator pumped at 885 nm

We report on a passively mode-locked TEM₀₀ Nd:YAG oscillator with the beam quality at M ² = 1.1 by a semiconductor saturable absorber mirror under 885 nm laser diode direct pumping for the first time. A maximum average output power of 17 W at a repetition rate of 80 MHz with 39 ps pulse width was obtained under the absorbed pump power of 38 W, corresponding to an optical-optical efficiency of 44% and the slope efficiency of 69%, respectively.     

CW red light generated by intracavity frequency doubling of a 1329 nm Nd:CNGG laser with LBO

We report an efficient laser emission on the 1329 nm ⁴ F _3/2 to ⁴ I _13/2 transition in Nd:CNGG under the pump with diode laser at 885 nm. Continuous wave (CW) 3.37 W output power at 1329 nm is obtained under 17.4 W of incident pump power; the slope efficiency with respect to the incident pump power was 36.2%. Moreover, intracavity frequency doubling with LiB₃O₅ (LBO) nonlinear crystal yielded 822 mW of red light at 665 nm. An optical-to-optical efficiency with respect to the incident pump power was 4.7%.     

Efficiency intracavity frequency-doubled Nd:CNGG-LBO green laser at 530.5 nm under direct 885 nm pumping into the emitting level

We report an efficient laser emission on the 1061 nm ⁴ F _3/2 to ⁴ I _11/2 transition in Nd:CNGG under the pump with diode laser at 885 nm. Continuous wave (CW) 5.4 W output power at 1061 nm is obtained under 17.4 W of incident pump power; the slope efficiency with respect to the incident pump power was 36.2%. Moreover, intracavity frequency doubling with LiB₃O₅ (LBO) nonlinear crystal yielded 1.75 W of green light at 530.5 nm. An optical-to-optical efficiency with respect to the incident pump power was 10.1%.     

A comparison of resonantly pumped Ho:YLF and Ho:LLF lasers in CW and Q-switched operation under identical pump conditions

Singly 0.5 at.% Ho doped crystals of YLiF₄ (YLF) and LuLiF₄ (LLF) are studied under identical pump conditions in continuous-wave (CW) and Q-switched operation. Longitudinal end-pumped CW laser performance shows Ho:LLF to have a slightly lower threshold and a slightly higher slope efficiency with respect to absorbed pump power than Ho:YLF. Both lasers were operated on π-polarization. At a cavity output coupling of 20% and a crystal length of 30 mm, the Ho:LLF (Ho:YLF) laser yielded 18.8 W (18 W) of CW output at a wavelength of 2067.8 nm (2064.0 nm) for 41.4 W (42.2 W) of absorbed pump power with a slope efficiency of 67.1% (65.6%) and an optical-to-optical efficiency of 45.4% (42.6%) with respect to absorbed pump power. With the same output coupling and a crystal length of 40 mm, the Ho:LLF (Ho:YLF) laser yielded 20.5 W (18.1 W) of CW output at a wavelength of 2067.7 nm (2064.3 nm) for 51.5 W (50.0 W) of absorbed pump power with a slope efficiency of 58.4% (55.4%) and an optical-to-optical efficiency of 39.8 (36.1%) with respect to absorbed pump power. The influence of the temperature of the cooling mount on CW laser performance was studied and showed very similar results for both laser materials. At full pump power, a slope of −155 mW/°C (−149 mW/°C) was observed for the Ho:LLF (Ho:YLF) laser with a crystal length of 30 mm. In Q-switched operation, the Ho:LLF (Ho:YLF) laser produced 37 mJ (38.5 mJ) at a repetition rate of 100 Hz with a pulse duration of 38 ns (35 ns) at a wavelength of 2053.1 nm (2050.2 nm) with a slope efficiency of 30.3% (31%) and an optical-to-optical efficiency of 14.2% (13.9%) with respect to absorbed pump power. The beam quality was nearly diffraction limited (M ²<1.1).     

Stable output, high power diode-pumped Tm:YLF laser with a volume Bragg grating

A stable output, high power diode-pumped Tm: YLF laser operating at 1908 nm with FWHM line width less than 0.1 nm is reported. Using a volume Bragg grating, 41.1 W of output with M ²∼2 under an incident pump power of 111.7 W was achieved, corresponding to an optical-to-optical conversion efficiency of 36.8% and a slope efficiency of 43.2%. A laser wavelength shift of only 0.3 nm with the incident pump power varying from 13.1 W to 111.7 W was observed.