Suppressing the preferential o-polarization oscillation in a high power Nd：YVO4 laser with wedge laser crystal

We observe the phenomenon of priority oscillation of the unexpected a-polarization in high-power Nd：YVO4 ring laser. The severe thermal lens of the a-polarized lasing, compared with the n-polarized lasing, is the only reason for the phenomenon. By designing a wedge Nd：YVO4 crystal as the gain medium, the unexpected a-polarization is completely suppressed in the entire range of pump powers, and the polarization stability of the expected zc-polarized output is enhanced. With the output power increasing from threshold to the maximum power, no a-polarization lasing is observed. As a result, 25.3 W of stable single-frequency laser output at 532 nm is experimentally demonstrated.     

Ti:sapphire laser pumped high average power laser crystal Nd:GGG with high efficiency output

High-quality neodymium doped GGG laser crystals have been grown by Czochralski (Cz) method. Results of Nd:GGG thin chip laser operating at 1.064 μm pumped by Ti:sapphire laser operating at 808 nm were reported. The slop efficiency was as high as 20%.     

Study on optical characteristics of Nd:YVO_4/YVO_4 composite crystal laser

Thermal effect in crystals is the main obstacle blocking diode-pumped solid state laser to get high and stable output, power. Diffusion bonding crystal has been demonstrated to be an effective method to relieve the thermal lensing theoretically based on the numerical heat analysis to the end-pumped anisotropic laser crystal. The temperature distributions in Nd:YV04/YVO4 composite crystal and conventional crystal were analyzed and compared. The end-pumped Nd:YVO4/YVO4 composite crystal laser was designed and set up with 2-cavity. The maximum output powers of 9.87 W at 1064 nm and 6.14 W at 532 nm were obtained at the incident purnp power of 16.5 W. The highest optical-optical conversion efficiencies were up to 59.8% at 1064 nm and 37.2% at 532 nm respectively.     

Q-switched mode-locked diode-pumped Nd:YVO_4 laser with a saturable Bragg reflector

We demonstrated a diode-pumped passively Q-switched mode-locked Nd:YVO4 laser by using a relaxed saturable Bragg reflector (SBR). Stable mode-locked pulse train with the repetition rate of -230 MHz was achieved and the pulse train was modulated by the Q-switched envelope with the repetition rate of -150 kHz. The maximum output of 4 W was obtained under the pump power of 13.5 W. The optical-to-optical efficiency was 30%. We also discussed the transition of each process having emerged.     

High power diode-pumped 914-nm Nd：YVO_4 laser

<正>A high power continuous-wave(CW) 914-nm Nd:YVO_4 laser at room temperature is presented.Using an end-pumped structure and employing an 808-nm diode-laser as the pump source,the maximum output power of 15.5 W of the 914-nm laser is achieved at the absorbed pump power of 40.2 W,with a corresponding average slope efficiencyη_s=65.6%.To the best of our knowledge,this is the highest output power of diode-pumped 914-nm laser.A beam quality factor M~2=2.8 at the output power of 15 W is measured by using the traveling knife-edge method.     

Contrastive study of two SESAMs for passive mode-locking in Nd:YVO_4 laser with low pump power

Two semiconductor saturable absorber mirrors (SESAMs), of which one is coated with 50% reflection film on the top and the other is not, were contrastively studied in passively mode-locked solid-state lasers which were pumped by low output power laser diode (LD). Experiments have shown that reducing the modulation depth of SESAM by coating partial reflection film, whose reflectivity is higher than that between SESAM and air interface, is an effective method to get continuous wave (CW) mode-locking instead of Q-switched mode-locking (QML) in low power pumped solid-state lasers. A simple Nd:YVO4 laser pumped by low power LD, in which no water-cooling system was used, could obtain CW mode-locking by the 50% reflector coated SESAM with average output power of ~ 20 mW.     

Multi-watt Q-switched Nd:YVO_4 laser with GaAs output coupler

A passively Q-switched operation of a diode-pumped Nd.YVO_4 laser is demonstrated, in which a GaAsfilm is used as the saturable absorber as well as the output coupler. At the pump power of 10 W, a stablefundamental-mode average power output of 2.11 W was obtained with a pulse duration of 140 ns, pulseenergy of 76 μJ and pulse repetition rate of 28 kHz. A theoretical analysis that describes the passiveQ-switching dynamics of GaAs is presented.     

Diode-pumped passively Q-switched Nd:YVO_4 laser with GaAs saturable absorber

The intracavity photon density is assumed to be of Gaussian spatial distributions and its longitudinal variation is also considered in the rate equations for a laser diode (LD) end-pumped passively Q-switched Nd:YVO4 laser with GaAs saturable absorber. These space-dependent rate equations are solved numerically. The dependences of pulse width, pulse repetition rate, single-pulse energy, and peak power on incident pump power are obtained. In the experiment, the LD end-pumped passively Q-switched Nd:YVO4 laser with GaAs saturable absorber is realized and the experimental results are consistent with the numerical solutions.     

Study of the optical bistability in the laser oscillation of Yb:GdVO4 crystal

We have studied the effect of optical bistability exhibited in the laser oscillation of Yb:GdVO₄ crystal, revealing the complexities arising from the coexistence and switching of σ and π polarization states characteristic of this crystal. In terms of absorbed pump power, the range for bistable operation can be in excess of 1 W, while the output power generated at the up-threshold can reach as high as 0.71 W. The studies also show significant influence of the Yb concentration, the crystal thickness, the output coupling, and the resonator configuration on the bistable laser operation.     

Suppressing effect of the laser extraction on heat generation in Nd:YAG

The suppressing effect of the laser extraction on heat generation in Nd:YAG was investigated. The extraction efficiency could be deduced from the slope efficiency, and heat generation in Nd:YAG could be obtained with the heat model developed, which was verified by the previous experiment. The essential reasons were given to explain the change trend of heat generation under the condition of laser extraction.     

500-W high average power,high beam quality Nd:YAG solid-state laser with one focusing reflector

In order to explore a 56-J high energy,high frequency lamp-pumped pulsed Nd:YAG solid-state laser, the main factors influencing the higher laser output energy are analyzed,the relation between output power and input power and reflectivity is simulated theoretically,and the effective measures to improve the efficiencies of the laser are brought forward.As a result,pulse width is tunable between 0.1 and 10 ms,frequency between 1 and 1000 Hz.When the input electrical power is 12 kW,the laser can output maximum single pulse energy of 56 J and average power of 500 W with the beam quality of 16.5 mm·mrad, total electro-optic efficiency of 4.2%,and the in stability of±2% output power.It is indicated that the parameters corresponds with the results of theoretical analysis and simulation.     

High peak power laser-diode-pumped passively Q=switched Nd:YVO_4/Cr~(4+):YAG laser

In this paper, we report a high peak power passively Q-switched laser-diode-end-pumped Nd:YVO_4/Cr~(4+):YAG laser polarized along the C axis, generating 4.23-W average power and 18-kW peak power (144-μJ pulse power) with 8.0-ns time duration (29.4-kHz repetition rate) at 1064 nm while the pump power is 21.2 W.     

Q-switched mode-locking with Cr4+ : YAG in a diode pumped Nd : GdVO4 laser

We have demonstrated passively Q-switched mode-locking in a laser-diode-pumped Nd:GdVO₄ laser with an intracavity Cr⁴⁺:YAG saturable absorber. At a pump power of 19.4 W, the Q-switched mode-locked laser produced an average output power of 3.22 W, and the repetition rates of the Q-switched envelope and the mode-locked laser pulse were 227 kHz and 144 MHz, respectively. The duration of the mode-locked pulse was within the sub-nanosecond range. PACS 42.55.Xi; 42.60.Fc; 42.60.Gd; 42.55.Rz     

High Power All-Solid-State Nd: YVO_4 laser and its intracavity SHG

Ｈｉｇｈ　Ｐｏｗｅｒ　Ａｌｌ－Ｓｏｌｉｄ－Ｓｔａｔｅ　Ｎｄ：ＹＶＯ＿４　ｌａｓｅｒ　ａｎｄ　ｉｔｓ　ｉｎｔｒａｃａｖｉｔｙ　ＳＨＧＨｉｇｈＰｏｗｅｒＡｌｌ－Ｓｏｌｉｄ－ＳｔａｔｅＮｄ：ＹＶＯ＿４ｌａｓｅｒａｎｄｉｔｓｉｎｔｒａｃａｖｉｔｙＳＨＧ￥ＺＨ...     

LD-pumped high repetition rate Q-switched Nd:YVO_4 laser by using La_3Ga_5SiO_(14) single crystal electro-optic modulator

A diode-end-pumped electro-optic (EO) Q-switched Nd:YVO4 laser operating at repetition rate of 10 kpps (pulses per second) was reported. A block of La3Ga5SiO14 (LGS) single crystal was used as a Q-switch and the driver was a metal oxide semiconductor field effect transistor (MOS-FET) pulser of high repetition rate and high voltage. At continuous wave (CW) operation, the slope efficiency of the laser was 46%, and maximum optical-to-optical efficiency was 38.5%. Using an output coupler with transmission of 70%, a 10-kpps Q-switched pulse train with 0.4-mJ monopulse energy and 8.2-ns pulse width was achieved, the optical conversion efficiency was around 15%, and the beam quality M2 factor was less than 1.2.     

120 W high repetition rate Nd:YVO<Subscript>4</Subscript> MOPA laser with a Nd:YAG cavity-dumped seed laser

A master oscillator power amplifier (MOPA) system in which the output from an end-pumped Nd:YAG oscillator cavity dumped at 500 kHz is scaled up by a four-stage Nd:YVO₄ amplifier is reported. Decrease in extraction efficiency of the amplifier chain with crystals different from that in the oscillator was analyzed. With the 5.4 W seed output, 118 W of power was extracted from the amplifier chain at the pump power of 345 W, with an extraction efficiency of 34.2% and an overall optical–optical efficiency of 30.9% for the MOPA system. The beam quality factors were measured as M _x ²=1.45 and M _y ²=1.59 in two orthogonal directions, respectively.     

Laser-diode-pumped Cr4+, Nd3+:YAG self-Q-switched laser with high repetition rate and high stability

A diode end-pumped self Q-switched Cr⁴⁺, Nd³⁺: YAG laser was established with 30-ns pulse width (FWHM) and 0.5-μJ pulse energy output. In normal pulse pumping operation, the lasing threshold changed greatly from 122 mJ to 2.4 mJ as the pump pulse frequency varied from 1 Hz to 500 Hz due to pumping-induced thermal effect. A pre-pumping method was proposed and the change of the lasing threshold was reduced; programmable Q-pulse output with maximum frequency of 16 kHz and high stability was achieved. Received: 16 January 2001 / Revised version: 21 May 2001 / Published online: 19 September 2001     

6.5-ns actively Q-switched Nd:YVO_4 laser operating at 1.34 μm

With a plano-concave cavity,diode-pumped continuous-wave(CW) and actively Q-switched Nd:YVO4 laser operating at 1.34 μm is demonstrated.Maximum CW output power of 4.76 W and Q-switched average output power of 2.64 W are obtained with output coupler(transmission T = 3.9%).For the Q-switching operation,the theoretically calculated pulse energy and pulse width,with a pulse repetition frequency(PRF) range of 5-40 kHz,coincide with the experimental results.With a T = 11.9% output coupler,the maximum peak power of 24.3 kW and minimum pulse width of 6.5 ns are obtained when the PRF is 10 kHz.To the best of our knowledge,this is the shortest actively Q-switched pulse duration ever obtained in a 1.3-μm Nd-doped vanadate laser.     

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.