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A Q-switched Er:YAG solid-state laser at 1645 nm based on black phosphorus (BP) saturable absorbers (SAs) was demonstrated firstly to our knowledge. The BP-SA was fabricated by drop-casting BP nanoplatelets dispersion on a YAG substrate and corresponding saturable absorption properties were characterized at 1.6 μm. By employing as-prepared BP-SAs, stable Q-switched laser operations were achieved with a pulse width of 2.8 μs and a repetition rate of 34 kHz, corresponding to the average output power of 0.33 W. The results verify that BP-SAs have great potential for pulsed 1.6 μm lasers.

A novel nickel–cobalt (NiCo)-layered double hydroxide (LDH) saturable absorber (SA) was fabricated by the liquid-phase exfoliation method and applied as the laser modulator for the first time. We successfully investigated the laser modulation performance of the NiCo-LDH SA at 2 µm with a passively Q-switched (PQS) Tm:YAG ceramic laser. The narrowest pulse width of 322.6 ns was obtained, corresponding to a pulse repetition frequency of 119.3 kHz and a single pulse energy of 2.10 µJ. As far as we know, this is the shortest pulse width of PQS Tm:YAG crystal and ceramic lasers with two-dimensional materials saturable absorber. The results show that NiCo-LDH SA is a promising candidate for the application of laser modulators at 2 µm.

Nickel-vanadium (NiV)-layered double hydroxide (LDH) was fabricated into a novel saturable absorber (SA) by the liquid phase exfoliation method and utilized as the laser modulator for the first time, to our best knowledge. We investigated a passive Q -switched Tm:YAG ceramic laser at 2 µm with the NiV-LDH SA. Under an absorbed pump power of 7.2 W, the shortest pulse width of 398 ns was obtained with an average output power of 263 mW and a pulse repetition frequency of 101.8 kHz, corresponding to a single pulse energy at 2.30 µJ. The results indicate that the NiV-LDH SA has great research potential in the field of laser modulation.

We demonstrate a narrow-linewidth linearly polarized 1645 nm Er:YAG laser, directly diode-pumped by a fiber-coupled continuous-wave laser diode at 1532 nm. Passive Q-switching is realized by a few-layer graphene saturable absorber. A maximum polarized average output power of 3.13 W is achieved at 23.28 W incident pump power. A pulse energy of as much as 58.8 μJ and pulse width of 4.21 μs are yielded at a 53.2 kHz pulse repetition rate. The spectrum and linewidth of the output beams are measured to be 1645.34 and 0.05 nm, respectively. This laser can be useful in the detection of atmosphere pollutants.

We demonstrate a potassium titanyl phosphate-based optical parametric oscillator (OPO) emitting at 1729 nm. A maximum output power of 1.56 W at 1729.4 nm is obtained with an original fundamental laser power of 5.48 W. The pulse with a pulse duration of 11.22 ns exceeds 3 mJ at a 500 Hz repetition rate. To our knowledge this is the highest energy output of an OPO laser emitting around 1.73 \mu m operating at a 100 Hz order of magnitude. This laser is primarily used for bond-selective imaging of deep tissue, a promising way for diagnosing vulnerable plaques in live patients.

We report high-energy linearly polarized operation of an Er:YAG laser at 1617 nm, resonantly pumped by quasi-continuous-wave 1470-nm laser diodes. A U-shape resonator incorporating two 0.25 at.% Er:YAG rods and an acousto-optic Q-switch was employed. Polarized output with pulse energy of 20.5 mJ and pulse width of 52 ns at a 50 Hz repetition rate was obtained. At the maximum output energy, the output beam quality M 2 was approximately 1.02 and 1.03 in horizontal and vertical directions, respectively. To the best of our knowledge, this polarized pulse energy is the highest ever reported for a directly diode-pumped Q-switched Er:YAG laser operating at 1617 nm.

An efficient laser diode end-pumped continuous-wave (CW) and AO Q-switched laser of Nd:LiLuF4 crystal with dual central wavelengths of 1053.1 and 1054.7 nm is reported for the first time. The maximum CW output power of 6.22 W was obtained at absorbed pump power of ∼14.6 W with the output transmission of 2%. The optical conversion efficiency is ∼43%, corresponding to a slope efficiency of about 48% with respect to the absorbed pump. For the Q-switched operation, the shortest pulse width of 17 ns was obtained at the pulse repetition frequency (PRF) of 0.5 kHz, resulting in a pulse energy of 2.24 mJ and peak power of 131.8 kW.

Diode end-pumped continuous-wave and passively Q-switched Nd:Lu x(x = 0.5) Y 1 − x VO 4 mixed crystal lasers were demonstrated. At the pump power of 12.6 W, the maximum output power of 6.7 W around 1066.5 nm was obtained with the output transmission of 27%. The optical conversion efficiency is 53.2%, corresponding to a slope efficiency of 55.8%. For pulsed operation, the shortest pulse width attained was 8.6 ns, with the pulse repetition frequency of 99 kHz, and the single pulse energy and the peak power were estimated to be 25.5 μJ and 2.96 kW, respectively.

Diode end-pumped continuous wave (CW) and passively Q-switched (PQS) laser performances of the mixed Nd:Gd0.33Lu0.33Y0.33VO4 crystal are investigated for the first time. At the pump power of 9 W, the highest output power is 3.66 W, with an optical conversion efficiency of 40.7% and a slope efficiency of 43.6%. For pulsed operation, the minimum pulse width of 9.2 ns with Cr4+:YAG as saturable absorber is attained with the repetition rate of 81.8 kHz, and the single pulse energy and peak power are estimated to be 9.78 J and 1.06 kW, respectively.

Resonantly gain-switched by a 1.9-μm Tm:YLF crystal laser, over 11 W ~ 2.1-μm laser output has been achieved from a Ho:LuAG rod laser with a slop efficiency of 83% with respect to absorbed pump power. The high quantum efficiency (~ 92%) was attributed to the compact cavity configuration, excellent mode overlap between the pump and laser beam, and efficient crystal cooling. Near the highest output level, the laser wavelength was centered at 2130 and 2101 nm, with the T = 8% and T = 20% output couplers, respectively. At 10-W power level, the laser beam quality was measured to be M2 ~ 1.02. The narrowest pulse width achieved was 20 ns and maximum pulse energy was over 4 mJ (2 kHz).

Lasers from Ho:YAG ceramic were reported in this paper. The Ho:YAG ceramic slab was end-pumped by a Tm:YLF laser whose central wavelength was 1.91 μm. At room temperature, with doping concentrations of 1 at.% Ho:YAG ceramic slab, continuous wave output power of 1.2 W at 2.09 μm was obtained under the absorbed pump power of 5 W, corresponding to a slope efficiency of 42.6% and a conversion efficiency of 24%.

Laser characteristics of a novel mixed laser crystal Nd:Lu0.15Y0.85VO4 was investigated. It is attractive for Q-switching with high repetition rate and short pulse width due to its suitable stimulated emission cross-section and short upper level lifetime. Continuous wave (CW) output power of 8.18 W was obtained at the pump power of 18.9 W, corresponding to the optical conversion efficiency of 43.3% and the slope efficiency of 47%. In the passive Q-switching operation, the minimum pulse width attained was 7.8 ns, with the pulse repetition frequency of 23.2 kHz, with the single pulse energy and peak power estimated to be 94.8 μJ and 12.2 kW, respectively.

We demonstrate a passively Q-switched Ho,Pr:LiLuF4 laser at 2.95 μm using a WS2 saturable absorber (SA). A shortest pulse width of 654 ns was achieved with an average output power of 82 mW and the repetition rate of 90.4 kHz at T = 2%. Our result reveals that WS2 -SAs have great potential to be the modulator in mid-IR wavelength range.

A continuous-wave (CW) and actively Q-switched Nd:Lux(x=0.15) Y 1-xVO4 laser was demonstrated for the first time. The maximum CW output power of 9.92 W was obtained, corresponding to an optical conversion efficiency of 52.5% and a slope efficiency of 56.1%. For actively Q-switched operation, a 10.4-ns pulse was attained with the repetition frequency of 10 kHz. Under the same conditions, the pulse energy and the peak power were estimated to be 0.6 mJ and 57.9 kW, respectively.

We describe high-energy Erbium-doped yttrium aluminum garnet (Er:YAG) lasers operating at 1617 nm, resonantly pumped using 1532 nm fiber-coupled laser diodes. A maximum continuous wave output power of 4.3 W at 1617 nm was achieved with an output coupler of 20% transmission under incident pump power of 29.7 W, resulting in an optical conversion of 14% with respect to the incident pump power. In Q-switched operation, the pulse energy of 11.8 mJ at 100 Hz pulse repetition frequency and 81 ns pulse duration was obtained. This energy is the highest pulse energy reported for a directly diode-pumped Q-switched Er:YAG laser operating at 1617 nm.

In order to obtain laser output around 1.6um with high power and high overall efficiency, 1532nm narrow-band LD directly pumped Er:YAG laser is investigated. Performance of laser output with distinct doping concentration of gain medium is recorded and compared. Using 0.25% doped, 4cm long Er:YAG rod as the gain medium, we get over 10W laser output with about 31W incident pump power. The optical efficiency is about 33% and the slope efficiency with respect to the absorbed pump power is as high as 83%. Up to now, this is the most efficient Er:YAG laser pumped in this manner with traditional rod or slab geometry.

CNC manufacturing online monitoring technology is a significant method to improve the processing quality and achieve an important part of intelligent processing. Based on OpenGL 3D graphics technology, a Computer Numerical Control (CNC ) Laser Manufacturing 3D model is established; base d on the model and the powerful ability of OpenGL, a CNC manufacturing on-line monitoring system is developed so as to achieve the ability of CNC remote real-time online monitoring in different working locations. Remote real-time online monitoring of different position of the CNC is realized. The online monitoring scope of the CNC is enlarged, with more flexibility to meet the demands of practical application, meanwhile the cost of hardware investment is greatly reduced. Keywords : OpenGL, three-dimensional modeling, online monitoring 1. INTRODUCTION OpenGL is a graphical environment developed by the Silicon Graphics (SGI) [1] , which is used for its graphics workstations independent of the windowing system, operating systems and hardware environment. It can run in the Windows, Mac OS, UNIX and other operating systems

An efficient, directly diode-pumped Er:YAG laser at 1617 nm was demonstrated. A folding mirror with high reflectivity for the s-polarized light at the laser wavelength was used to achieve a linearly polarized laser. A maximum continuous-wave output power of 7.73 W was yielded under incident pump power of 50.57 W, and the optical conversion efficiency with respect to incident pump power was ∼15.28%, which was the highest optical conversion efficiency with directly diode-pumped Er:YAG lasers up to now; in Q-switched operation, the maximum pulse energy of 7.82 mJ was generated with pulse duration of about 80 ns at a pulse repetition frequency of 500 Hz.

We report a polarized, narrow-linewidth Er:YAG laser operating at 1645 nm, in-band pumped by a continuous-wave (CW), narrowband 1532 nm fiber-coupled laser diode (LD). A maximum polarized continuous wave output power of 8.45 W was obtained, resulting in an optical conversion efficiency of 56% with respect to the absorbed pump power. The central wavelength was measured to be 1645.45 nm, with a full width at half-maximum of 0.13 nm. For Q-switched operation, pulse energy of 12 mJ at 100 Hz pulse repetition frequency and 95 ns pulse duration was yielded. To the best of our knowledge, this polarized pulse energy is the highest energy reported for a Q-switched Er:YAG laser pumped by a CW LD.

We report, for the first time to our knowledge, an acousto-optic Q-switched Er3+:Yb3+:YVO4 laser end-pumped by a fiber-coupled diode laser at 976 nm. A maximum continuous wave output power of 230 mW at 1602.6 nm was obtained with an output coupler of 2% transmission under an absorbed pump power of 7.2 W. In Q-switched operation, a wide range of repetition rates from 500 Hz to 50 kHz was demonstrated. 0.19 mJ maximum pulse energy with 130 ns pulse duration was obtained at a repetition rate of 500 Hz. A reduced storage time of the upper laser level was discovered, which was suggested to be a result of up-conversion loss.

We first report an all-solid-state tunable mid-infrared singly resonant optical parametric oscillator based on a 1532 nm laser diode resonantly pumped, Q-switched 1.645 μm Er:YAG laser. An MgO-doped periodically poled lithium niobate was used as the nonlinear material. At the pulse repetition frequency of 2 KHz, a maximum overall average output power of 0.95 W with pump power of 2.8 W was achieved, corresponding to a conversion efficiency of 34% and a slope efficiency of 38%. The temperature tuning was performed giving signal and idler ranges of 2.67 to 2.71 μm and 4.18 to 4.31 μm, respectively.

Energy transfer upconversion induced thermal effects are mainly responsible for the low efficiency of laser diode pumped Er:YAG lasers. The current work adopts Er:YAG rods with 0.25% Er(3+) doping concentration, instead of the commonly used rods with 0.5% Er(3+) doping concentration. Results show that the thermal effect is greatly alleviated. A continuous-wave output of 10.2 W is obtained using 31 W incident pump power. Optical-optical efficiency is approximately 33%. Slope efficiency, with respect to the absorbed pump power, is as high as 83%, which is close to the quantum efficiency. In a Q-switched operation, 7 mJ pulses with a pulse width of ~65 ns are obtained at 100 Hz PRF.

In order to conveniently and precisely estimate the spot size of laser modes in continuously single-end-pumped solid-state lasers, a ray matrix for the thermal-induced lenslike medium with exponential heat distribution along the axial direction is, for the first time to our best knowledge, derived under assumptions of only radial heat flow and uniform pump spot size. An equivalent optical model is also developed and especially modified for a lenslike gain medium in a continuously single-end-pumped solid-state laser. The result is verified by discussing how it fits the practical cases much better than the previous simplified model and by numerical simulation in a practice problem. This work is especially important in cases with a relatively long gain medium, which has been used more and more frequently in recent years.

We demonstrated a diode-pumped continuous wave and passively Q-switched Nd:Lu(x)Y(1-x)VO4 laser at 1.34 μm with V3+:YAG as the saturable absorber. The crystal Nd:Lu(x)Y(1-x)VO4 with equal ionic ratio (x = 0.5) shows better laser performance. The maximum continuous wave output power of 1.45 W was obtained with the optical efficiency of 20.1% and the slope efficiency of 24.5%. For the pulsed operation, the minimum pulse width achieved was 42 ns with the pulse repetition frequency of 142 kHz, and the single pulse energy and the peak power were estimated to be 6.62 μJ and 157.6 W, respectively.

Characteristics of Tm:YAG ceramic for high efficient 2-μm lasers are analyzed. Efficient diode end-pumped continuous-wave and Q-switched Tm:YAG ceramic lasers are demonstrated. At the absorbed pump power of 53.2W, the maximum continuous wave (cw) output power of 17.2 W around 2016 nm was obtained with the output transmission of 5%. The optical conversion efficiency is 32.3%, corresponding to a slope efficiency of 36.5%. For Q-switched operation, the shortest width of 69 ns was achieved with the pulse repetition frequency of 500 Hz and single pulse energy of 20.4 mJ, which indicates excellent energy storage capability of the Tm:YAG ceramic.