Diodes-double-end-pumped high efficiency continuous wave 36 W TEM00 mode Nd:GdVO4 laser

A effective continuous-wave (CW), high power laser generated using a YVO₄/Nd:YVO₄ composite crystal is presented. 18.8 W output power in multi-mode has been achieved with a maximum absorbed pump power of 31.2 W, corresponding to an optical-to-optical efficiency of 60.26%. In TEM₀₀ mode operation, 15.1 W output power also has been achieved with the maximum absorbed pump power of 31.2 W, corresponding to an optical-to-optical efficiency of 47.69%. With a 200 mm focal-length positive lens and using the moving knife-edge method, the beam quality factor is measured to be M² = 1.2 for TEM₀₀ mode beam.     

Efficient end-pumped slab Nd:YVO4 laser with a multifolded quasi-concentric resonator

A novel end-pumped slab Nd:YVO₄ laser with a multifolded quasi-concentric resonator (FCR) is reported. This planar-folded stable resonator matches the sheet-shaped pump volume with the TEM₀₀ mode and yields highly efficiently laser operation with a good beam quality. In a prototype experiment, a 19.55-W output was achieved with a pump power of 45 W, which was single mode in one direction. In addition, the optical-to-optical efficiency reached 43.4%. After introducing a telescope system into the folding plane, a 10.23-W quasi-TEM₀₀ output was obtained, and the overall efficiency was 22.7%.     

Compact TEM00 Nd:YVO4 slab laser end pumped by an LD bar

In this paper, we present a laser-diode (LD) bar end-pumped Nd:YVO₄ slab laser, which uses a simple coupling system and a compact quasi-concentric resonator (QCR). A TEM₀₀ output was obtained with a pump width varied from 2.57 to 9.44 mm and the slope efficiency is kept at about 48%. Under 40-W pumping, a maximum TEM₀₀ output of 15.84 W was achieved and the optical-to-optical efficiency was 39.6% correspondingly.     

914 nm LD end-pumped 31.8 W high beam quality E-O Q-switched Nd:YVO4 laser without intracavity polarizer

We report a 914 nm LD end-pumped high power, high beam quality (M _x ² = 1.378, M _y ² = 1.287) electro-optical Q-switched Nd:YVO₄ laser with TEM₀₀-mode output. At the absorbed pump power of 67.6 W, a 31.8 W 1064 nm Q-switched laser with 43 ns pulse duration was achieved at 100 kHz repetition rate, corresponding to an optical-to-optical efficiency of 47%. The maximum pulse energy and shortest pulse width were 1.67 mJ and 18.5 ns at 10 kHz, and the calculated peak power was 90.3 kW. To the best of our knowledge, this is the highest Q-switched output power ever obtained for a Nd:YVO₄ oscillator pumped at 914 nm.     

High efficiency passive mode-locked Nd:YVO<Subscript>4</Subscript> laser based on SESAM under direct pumping at 880 nm

We report on an 880 nm LD pumped passive mode-locked TEM₀₀ Nd:YVO₄ laser based on a semiconductor saturable absorber mirror (SESAM), with a high optical-to-optical conversion efficiency of 67.3%, and a slope efficiency of 71%. When the absorbed pump power was 11 W, 7.4 W average output power of 1064 nm continuous-wave mode-locked laser was achieved. To our knowledge, this is the highest optical-to-optical conversion efficiency among all the published reports of 880 nm LD pumped SESAM passive mode-locked lasers. The repetition rate of mode-locked pulse was 80 MHz with 26 ps pulse width. The maximum pulse energy and peak power were 92.5 nJ and 3.6 kW, respectively.     

LD泵浦Nd:YVO_4双波长运转腔内和频491nm激光器

分析了Nd:YVO4激光器实现双波长运转及腔内和频的条件,利用一种LD泵浦Nd:YVO4晶体产生1 064 nm和914 nm双波长激光束,采用一个线性平凹腔结构,利用腔内Ⅰ类临界相位匹配LBO和频,获得了连续波输出的全固态激光器。实验采用端面结构,在5.0 W的808 nm泵浦功率下,获得了最高功率为2.5 mW连续波TEM00的激光输出,光-光转换效率为0.05%。     

High-pulse-energy passively mode-locked Nd:YVO4 laser without spatial hole burning effect

We report on a high-pulse-energy 888 nm diode-pumped passively mode-locked TEM₀₀ Nd:YVO₄ oscillator without spatial hole burning (SHB) effect in active medium. At a pump power of 40 W, the oscillator produced pulse energy up to 270 nJ at a repetition rate of 50 MHz, corresponding to average power of 13.5W with 34% optical-to-optical efficiency. To the best of our knowledge, it is the highest pulse energy obtained at the same pump power. The pulse duration produced varied from 16 to 59 ps. By varying the pump power, we observed a pulse duration ranging from 52 to 59 ps while the time-bandwidth product remained 0.88, and the factors that affect the pulse duration were also discussed. Meanwhile, a novel method of adjusting output coupling (OC) was introduced, which can simplify the structure of laser.     

Compact diode-directly-pumped passively mode-locked TEM<Subscript>00</Subscript> Nd:GdVO<Subscript>4</Subscript> laser at 1341 nm using a semiconductor saturable absorber mirror

We report on a compact 880-nm diode-directly-pumped passively mode-locked TEM₀₀ Nd:GdVO₄ laser at 1341 nm with a semiconductor saturable absorber mirror (SESAM) for the first time. Under the absorbed pump power of 14.6 W, the maximum output power of 1.27 W was obtained at the repetition rate of 85.3 MHz with the pulse width of 45.3 ps, corresponding to an optical-optical efficiency of 8.8% and the slope efficiency of 33.3%, respectively. The beam quality factor was measured to be M ² = 1.18, indicating a TEM₀₀ mode.     

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.     

High-power and efficiency continuous-wave operation of <Emphasis Type="Italic">a</Emphasis>-cut Ho:YAP laser at room temperature

We report the continuous-wave (CW) operation of a room-temperature a-cut Ho:YAP laser resonantly end-pumped by a diode-pumped Tm:YLF laser at 1.91 μm. A maximum CW output power of 14.6 W at 2118.7 nm for a-oriented Ho:YAP was obtained, corresponding to the slope efficiency of 69.35% and optical-to-optical conversion efficiency of 63.04% with respect to absorbed pump power. The laser operated at a single mode (TEM₀₀) with the beam quality factor of M ² ∼ 1.51.     

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.     

Compact 7.8-W 1-GHz-repetition-rate passively mode-locked TEM00 Nd:YVO4 laser under 880 nm diode direct-in-band pumping

We demonstrate a compact high-power passively mode-locked TEM₀₀ Nd:YVO₄ laser with 1 GHz repetition rate by 880 nm diode direct-in-band pumping. At the absorbed pump power of 19.9 W, a stable mode-locked output power of 7.8 W was obtained with the pulse width of 21.4 ps and a beam quality factor of M² < 1.5, corresponding to an optical-optical conversion efficiency of 39.2%.     

High-power diode-end-pumped Nd:YVO4 laser: thermally induced fracture versus pump-wavelength sensitivity

We report two kinds of compact and efficient diode-end-pumped TEM₀₀ lasers with output power >25 W at ≈50 W of incident pump power. One laser consists of a single 0.3 at. % Nd:YVO₄ crystal in a V-type cavity, the other laser includes two 0.5 at. % Nd:YVO₄ crystals in a linear cavity. Experimental results show that lowering Nd³⁺ concentration can be beneficial in extending the fracture-limited pump power but it also increases the sensitivity of the pump wavelength due to the overlapping efficiency. Received: 19 February 2000 / Revised version: 30 May 2000 / Published online: 20 September 2000     

High efficiency TEM00 mode, diode-pumped, conduction-cooled, Nd:YAG zig-zag slab laser

We report a compact, conduction-cooled, highly efficient, continuous wave (CW) Nd:YAG slab laser in diode-side-pumped geometry. To achieve high efficiency, a novel laser head for Nd:YAG slab has been developed. For an absorbed pump power of 27.6 W, maximum output power of 10.4 W in multimode and 8.2 W in near-diffraction-limited beam quality has been obtained. Slope and optical-to-optical conversion efficiencies are 45.3% and 37.7% in multimode with beam quality factors (M²) in x and y directions equal to 32 and 8, respectively. TEM₀₀ mode operation was achieved in a hybrid resonator with slope and optical-to-optical conversion efficiencies of 43.2% and 29.7%, respectively. Beam quality factors in x and y directions are ?1.5 and ?1.6 for the whole output power range. The laser radiation was linearly polarized and polarization contrast ratios are >1200:1 in the multimode and 1800:1 in the TEM₀₀ mode operation. In passive Q-switching with Cr⁴⁺:YAG crystal of 68% initial transmission, 18 ns pulsewidth has been achieved with an average power of 2 W at a repetition rate of 16 kHz.     

All-solid-state Nd:YVO<Subscript>4</Subscript> laser at 1342 nm under 914 nm diode laser pumping

A Nd:YVO₄ crystal was pumped directly into the emitting level by a laser diode at 914 nm. We achieved an output power of 1.46 W at 1342 nm for an incident pump power of 18.3 W, corresponding to an optical-to-optical conversion efficiency of 8.0%. The fluctuation of the output power was better than 2.3% in the given 30 min. The beam quality M₂ factor value was equal to 1.15 at the maximum output power.     

LD泵浦Nd:YVO4/LBO临界相位匹配腔内倍频瓦级绿光激光器

报道了一种光纤耦合LD泵浦Nd:YVO₄晶体、腔内Ⅰ类临界相位匹配(角度匹配)LBO倍频、瓦级输出的全固态绿光激光器的设计方法和实验结果.采用短三镜折叠腔结构,通过对热透镜焦距的估算及计算机优化设计选取合适的谐振腔参量,在8 W的泵浦功率下,获得了1.6 W绿光基模输出,光-光转换效率达20%.经测量,绿光的偏振比超过400:1,4 h功率稳定度为±1.6%.     

Compact TEM<Subscript>00</Subscript> grazing-incidence Nd:GdVO<Subscript>4</Subscript> laser using a folded cavity

A compact diode-side-pumped Nd:GdVO₄ laser system using a folded cavity and grazing-incidence configuration is presented. The highest multimode output power obtained was 21.8 W at 36 W of effective diode pump power. Highest optical-to-optical conversion efficiency of 61.5% was achieved at 33 W of effective diode pump power with 20.3 W of multimode output power. For single-mode TEM₀₀ operation, an intracavity telescope was adopted for mode matching in the horizontal direction. Because of the folded cavity and the intracavity telescope, this laser head was the most compact to our knowledge of the TEM₀₀ grazing-incidence laser geometry. At last, an output power of 15 W was produced at 36 W of effective diode pump power. The stable Q-switching operation was also obtained. PACS 42.55.-f; 42.55.Xi; 42.60.Gd     

Efficient and high-power laser-diode single-end-pumped Nd：YVO4 continuous wave laser at 1342nm

A compact, efficient and high-power laser diode （LD） single-end-pumped Nd：YVO4 laser with continuous-wave emission at 1342 nm is reported. With a single crystal single-end-pumped by fibre-coupled LD array, an output power of 7.36W is obtained from the laser cavity of concave-convex shape, corresponding to an optical-to-optical efficiency of 32.8%. The laser is operated in TEM00 mode with small rms amplitude noise of 0.3%. The influences of the Nd concentration, transmissivity of the output mirror and the cavity length on the output power have been studied experimentally.     

8.9-W continuous-wave, diode-end-pumped all-solid-state Nd:YVO4 laser operating at 914 nm

A high power laser-diode-array end-pumped 0.2 at % Nd:YVO₄ continuous-wave (CW) laser operating at 914 nm is reported in this letter. The maximum output power of 8.9 W was obtained at the incident pump power of 48.0 W, giving the corresponding optical efficiency of 18.5% and the average slope efficiency of 25.7%. The beam quality factor was measured to be M ² = 2.71 at the output power of 8.0 W by the traveling knife-edge method.     

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.