LD-pumped passively Q-switched red laser at 660 nm

A laser diode (LD) pumped Nd:YAG red pulse laser at 660 mn was presented by V:YAG passively Q-switching and LBO intracavity frequency doubling. With 1.6-W incident pump power, average output power of 46-mW, pulse duration (FWHM) of 23.3 ns, pulse repetition rate of 21.6 kHz, peak power of 91.4 W, and single pulse energy of 2.13 μJ were obtained. The beam quality factor M2 was less than 1.2. The fluctuations of pulse energy and repetition rate were less than 3% in 4 hours. The pulsed laser at 660 nm is expected to be used as the pump source of Cr3+:doped crystal to obtain the gain-switched tunable laser.     

Random fiber laser operating at 1,115 nm

We experimentally demonstrate a random fiber laser operating at 1,115 nm using a LD-pumped Yb-doped fiber laser as the pump source. We achieve about 270 mW lasing output in a 50 km standard communication optical fiber with slope efficiency more than 28 %. A new wavelength is provided for the application of random distributed feedback fiber lasers as light sources.     

Mode-locked 0.5 μJ fiber laser at 976 nm

We report on high-energy femtosecond pulse generation from an ytterbium-doped rod-type fiber oscillator emitting around 976 nm. Self-starting and stable single-pulse operation are demonstrated with 4.2 W of average output power at a repetition rate of 8.4 MHz. The resulting energy level reaches 0.5 μJ. Because of the all-normal dispersion of the laser cavity, output pulses are naturally chirped with a duration of 14 ps. External compression using diffraction gratings shortens the pulse duration down to 460 fs.     

Diode-pumped Q-switched Nd:YLF laser at 1313 nm

In this letter, we describe the operation of an end-pumped acousto-optic Q-switched Nd:YLF laser. According to the theoretical analysis and calculation for Nd:YLF crystal, the thermal focal length of σ-polarized laser is positive in plane-parallel resonator, while that of π-polarized laser is negative. Hence laser operation at σ-polarized 1313 nm should be stable in plane-parallel cavity. When absorbed pump power is 12.45 W and the pulse repetition frequency is 10 kHz, 3.1 W output laser at 1313 nm is achieved. As a result, the optical–optical conversion efficiency is 25.4 % and slope efficiency is 31.2 %, respectively.     

Passively mode-locked Nd：GdVO4 laser at 912nm

This paper demonstrates the passively mode-locked Nd：GdVO4 laser operating on the ^4F3/2-^4I9/2 transition at 912 nm by using a semiconductor saturable-absorber mirror for passive mode locking, stable continuous wave modelocked 912nm laser was achieved with a repetition rate of 176 MHz. At the incident pump power of 17.7W, 22.6mW average output power of stable mode-locked laser was obtained with a slope efficiency of 0.3%.     

Plasma-based X-ray laser at 21 nm for multidisciplinary applications

An overview of recent advances in applications of currently the most energetic X-ray laser at 21 nm is given. The unique parameters of this half-cavity based X-ray laser such as record output energy of 10 mJ, highly symmetric beam, robustness and reproducibility, have made it possible to carry out a number of multidisciplinary scientific projects featuring novel applications of intense coherent X-ray radiation. Selected results obtained in these experiments are reviewed, including X-ray laser probing of dense plasmas, measurements of transmission of focused soft X-ray radiation at intensities of up to 10¹² W cm^-2, measurements of infrared laser ablation rates of thin foils, and ablative microstructuring of solids.     

High-peak-power passively Q-switched Nd:YAG laser at 946 nm

We demonstrate a high-peak-power quasi-continuous-wave diode-pumped passive Q-switched Nd:YAG laser at 946 nm. We make a thorough comparison of the output performance between the saturable absorbers of InGaAs quantum wells (QWs) and a Cr⁴⁺:YAG crystal. Experimental results reveal that the saturable absorber of InGaAs QWs is superior to the Cr⁴⁺:YAG crystal because of the low nonsaturable losses and leads to a pulse energy of 330 μJ with a peak power greater than 11 kW.     

Diode-end-pumped Tm:GdVO4 laser operating at 1818 and?1915?nm

High power operation at 1818 and 1915 nm has been demonstrated from a Tm:GdVO₄ laser operating in quasi-continuous-wave mode with a maximum measured power of 8.7 W and a laser output energy of 175 mJ was observed in a 20 ms pulse at 1.9 μm. The operation at 1818 nm is the shortest wavelength achieved at multi-watt power levels for a Tm-doped solid-state laser without intra-cavity tuning elements. It has been shown that by careful analysis of the emission spectra, the Tm:GdVO₄ laser can be tuned over a 100 nm wavelength range simply by appropriate selection of the reflectivity of the output coupler.     

Quasi-three-level neodymium-doped yttrium aluminum garnet laser emitting at 885 nm

We present a diode-pumped quasi-three-level neodymium-doped yttrium aluminum garnet (Nd:YAG) laser at 885?nm, based on the F_3/24-I_9/24 transition, generally used for a 946?nm emission. Combined with polarization components (Nd:YAG), the electro-optical crystal KH₂PO₄ (KDP) formed a Lyot filter in the cavity and compressed the available gain bandwidth. With an incident pump power of 9.2?W, a 714?mW continuous-wave (CW) output at 885?nm was achieved, and the optical-to-optical efficiency was 7.8%. With an adjustable voltage applied to the KDP crystal, the laser wavelength could be tuned from 885?nm to 884?nm. A simultaneous dual-wavelength Nd:YAG laser at 885?nm and 884?nm was also realized by adjusting the free spectral range of the Lyot filter. To our knowledge, it is the first study that has realized the tuning between the 884 and 885?nm lines and the simultaneous dual-wavelength CW laser operation at 885?nm and 884?nm.     

Study on CW Nd:YAG infrared laser at 1319 nm

A continuous wave (CW) Nd:YAG infrared laser at 1319 nm is reported in this paper. The energy level of 1319-nm wave was analyzed. The repression of 1064-nm lasing and enhancement of 1319-nm output power were discussed. Mirror coating and cavity structure were studied and a maximum CW output power of 43 W at 1319 nm was achieved in experiments.     

Diode-pumped passively Q-switched Nd : YAG laser at 1123 nm

A diode-pumped Nd:YAG laser at 1123 nm is passively Q-switched by using a low doping concentration Cr⁴⁺:YAG crystal as a saturable absorber. When pumped by a 1.5-W laser diode, the laser produces pulses of 50-ns duration with a pulse energy of as much as 15 J and a peak power of 300 W at a pulse-repetition rate of 10 kHz. PACS 42.60.Gd; 42.55.Rz; 42.55.Xi     

High-resolution laser spectroscopy on H2 at 97–98 nm

A narrowband tunable eXtreme UltraViolet (XUV) laser source is used for a high resolution study of the Lyman (B ¹ _u ⁺ X ¹ _g ⁺ ) band system of molecular hydrogen. Seven rotational transitions of two vibrational bands, (10,0) and (11,0), in the wavelength range from 97.2–98.3 nm have been investigated for the first time under sub-Doppler molecular beam conditions. A calibration procedure using the I₂ standard in the visible yielded an absolute frequency accuracy of 0.02 cm^–1. The obtained H₂ transition frequencies provide a calibration standard in the extreme ultraviolet wavelength region.     

Laser diode-array pumped Nd:YAlO_3 CW laser at 1079.5nm and 1341.4nm

Two key problems,spectral matching and spatial overlap between pumpingbeam and the laser mode in the active material,of diode-laser-arrays(LD)end-pumped solid-state laser have been discussed.Initial experimental results were given for LD end-pumpedTEM_(00) CW Nd:YAlO_3 laser at the wavelength of 1079.5nm and 1341.4nm.The outputpower at 1079.5nm is 24.4mW with 14.5％ slope efficiency,and the output power is 1.2mW at 1341.4nm.     

High-power Nd:YVO4/BaWO4 intracavity Raman laser emitting at 1,103?nm

A compact BaWO₄ Raman laser is realized with a diode-end-pumped acousto-optically Q-switched YVO₄/Nd:YVO₄ laser. Based on the Raman shift at 332?cm^?1 of BaWO₄, first-Stokes generation at 1,103?nm is generated. At a pump power of 11.3?W and a repetition rate of 45?kHz, an average power of 1.59?W is obtained. The pulse width is measured to be 36.8?ns and the beam quality factor (M ²) in the horizontal and vertical directions is determined to be 1.56?±?0.1 and 1.41?±?0.1, respectively. The thermal focal lengths of the laser medium and Raman medium are calculated theoretically.     

Single-frequency linearly-polarized 1083?nm all fiber nanosecond laser

Single-frequency linearly-polarized 1083?nm all fiber nanosecond master-oscillator power amplifier laser system is demonstrated. A ring laser, whose key components are one saturable absorber and two polarization controllers, delivers a single-frequency continuous wave laser. Using an electro-optic modulator as the modulator, the pulse laser seed is obtained by modulating the CW laser. By amplifying the pulse seed to the average power of 61.6?W in three stages, a single-frequency linearly-polarized laser with pulse duration of 16?ns, repetition rate of 10?MHz and pulse energy of 6.16???J is obtained. No nonlinear effect is observed in our experiment. Higher output power can be obtained by increasing LDs of the main amplifier.     

All solid-state sum-frequency generation of 1.12-W continuous-wave laser at 588 nm

A new resonator design for doubly resonant continuous-wave(CW)intracavity sum-frequency mixing (SFM)is reported.1.12 W of coherent radiation at 588 nm is generated by mixing 1062-nm Nd:GdVO_4 laser and 1319-nm Nd:YAG laser.The optical-to-optical conversion efficiency is up to 3.7%.     

Absolute frequency measurement of the iodine-stabilized He-Ne laser at 633 nm

The absolute frequency of an iodine-stabilized He-Ne laser at 633 nm stabilized on the i (or a₁₃) component of the 11-5 R(127) hyperfine transition of the ¹²⁷I₂ molecule is measured using a femtosecond optical comb generator and an iodine-stabilized Nd:YAG laser standard at 1064 nm. We link the measured absolute frequency to the current internationally adopted value via frequency intercomparison between JILA and the Bureau International des Poids et Mesures (BIPM), leading to the determination of the absolute frequency of the BIPM-4 standard laser. The resulting absolute frequency f_i(BIPM) of the BIPM-4 standard laser is f_i(BIPM)=473612214711.9±2.0 kHz, which is 6.9 kHz higher than the value adopted by the Comité International des Poids et Mesures (CIPM) in 1997. Received: 29 May 2000 / Revised version: 13 September 2000 / Published online: 22 November 2000     

Nd:GSAG-pulsed laser operation at 943 nm and crystal growth

Laser activity of neodymium-doped gadolinium scandium aluminum garnet (Nd:GSAG) on the transition with an output wavelength around 943 nm was investigated. The emission cross-section was measured with spectroscopic and amplifier approaches demonstrating the applicability of the Nd:GSAG laser for water vapor detection. A Q-switched laser setup delivered 150 ns pulses with 26 mJ output energy and 9% optical to optical efficiency. The laser was diode pumped with up to 50 Hz repetition rate. In the long pulse mode a pulse energy of 83 mJ with 32% optical efficiency was achieved. The output wavelength was controlled by injection seeding. PACS 42.55.Xi; 42.70.Hj     

High-efficiency direct-pumped Nd:YLF laser operating at 1321 nm

We present a high-efficiency Nd: LiYF₄ (Nd:YLF) laser operating at 1321 nm pumped directly into the emitting level, ⁴F_3/2. The linear polarization of the pump diode laser was maintained by a short fiber. At the absorbed pump power of 7.3 W, as high as 3.6 W of continuous-wave output power at 1321 nm is achieved. The slope efficiency with respect to the absorbed pump power was 0.52. To the best of our knowledge, this is the first demonstration of such a laser system. Comparative results obtained for the pump with a diode laser at 806 nm, into the highly absorbing ⁴F_5/2 level, are given in order to prove the advantages of 880 nm wavelength pumping.