YAG Composite Crystal Research Articles

Thermal Effect Analysis of Continuous LD End-Pumped Square YAG/Yb∶YAG Composite Crystal

Thermal Effect Analysis of Continuous LD End-Pumped Square YAG/Yb∶YAG Composite Crystal

Temperature Field of Continuous LD End-Pumped YAG/Yb∶YAG Composite Crystal

Temperature Field of Continuous LD End-Pumped YAG/Yb∶YAG Composite Crystal

Heating and Fusion of A Tungsten Micro Sphere using Powerful Laser Irradiation

The intense laser irradiation of a micro/nano size W sphere sample is considered in the present paper. Like numerical example, we choose a sphere with a radius of 1 µm. The present article’s point consists of approximating that the target’s temperature homogenization time is of the same order of magnitude as the first laser pulse duration. Our model is valid in the radius limits: 10 nm to 10 µm. We consider like heating source a laser beam with YAG/Nd:YAG/ Cr4+:YAG composite crystal. The nature of the interaction between a laser beam and small dimension tungsten (W) sample is of great importance for both theoretical and experimental perspectives. In principle, we have three stages: i) laser- W bulk interaction; ii) plasma formation, heating, and iii) adiabatic expansion. In the present paper, we will focus on the first two stages of laser pulse interval.

High peak power, multi-wavelength, passively Q-switched Raman lasers based on Yb:YAG/Cr4+:YAG composite crystal

Stable, multi-wavelength, high peak power, passively Q-switched Raman lasers based on Yb:YAG/Cr4+:YAG composite crystal and c-cut YVO4 crystal have been demonstrated under quasi-continuous-wave laser diode end-pumping. A Raman laser with a pulse energy of 50 μJ and a pulse width of 0.88 ns is obtained. The corresponding pulse peak power reaches 56.9 kW, which to our best knowledge is the highest peak power achieved in intracavity Raman lasers with Yb3+ ion-doped crystals as the gain medium. Stable pulse trains of the fundamental lasers and Raman lasers were achieved at different pump pulse energies. These findings have potential applications in nonlinear frequency conversion, photodynamic therapy, industrial processing and terahertz wave generation.

Multi-watt passively Q-switched self-Raman laser based on a c-cut Nd:YVO4 composite crystal

An in-band pumped passively Q-switched (PQS) self-Raman laser with a c-cut Nd:YVO4 composite crystal is demonstrated for the first time to our knowledge. A Cr4+:YAG composite crystal was utilized to improve the stability and misalignment sensitivity of the resonator. The PQS self-Raman output performance was systematically investigated with different initial transmissions (T0) of the Cr4+:YAG and different transmissions (TS) of the Raman output coupler. In addition, the focus position of the incident pump beam and cavity length have been optimized during the experiment. With Cr4+:YAG of T0=90% and output coupler of TS=10%, the maximum average output power at 1178 nm was up to 2.53 W under the absorbed pump power of 20.6 W, corresponding to an optical-to-optical conversion efficiency of 12.3%. The pulse repetition frequency and pulse width were measured to be 39.1 kHz and 20.4 ns, respectively, and the corresponding pulse energy and peak power were calculated to be 64.7 μJ and 3.2 kW. At the full output power, the fluctuation of Raman output power was less than ±0.5% within one hour. To the best of our knowledge, we have improved the PQS self-Raman laser about 3.2 times.

Compact passively Q-switched RbTiOPO4 cascaded Raman operation.

Compact passively Q-switched RbTiOPO4 cascaded Raman laser operation has been investigated for the first time, to our knowledge. A Nd:YAG/Cr4+:YAG composite crystal was adopted for passively Q-switched fundamental laser generation. 440mW multi-Stokes laser output with X(ZZ)X configuration according to the Porto notations was achieved under the incident pump power of 10W. The measured spectra contained three wavelengths of 1149, 1165, and 1185nm based on the Raman shift of 271 and 687 cm-1. Different from actively Q-switch cascaded Raman laser with Stokes wave from low order to high order oscillating in sequence, three intensity lines were output for the whole experiment in this passively Q-switched multi-Stokes laser. The output spectra could be varied and optimized based on the output coupler coating design. Output spectra not sensitive to incident pump power for passively Q-switched cascaded Raman laser have advantages in multiwavelength laser applications.

High-repetition-rate, high-peak-power burst mode laser with YAG/Nd:YAG/Cr4+:YAG composite crystal

A high-repetition-rate, high-peak-power 808 nm LD pumped burst mode 1064 nm laser is demonstrated with a YAG/Nd:YAG/Cr4+:YAG composite crystal. A pulse burst energy of 13.2 mJ in a duration of 1 ms is obtained at 31.1 kHz with an optical-to-optical efficiency of 27.2% and a single pulse energy of 425.8 μJ. The pulse width keeps nearly invariable during the pump region and the shortest pulse width is 1.9 ns. The peak power of pulse burst laser reaches 373.7 kW at 10.2 kHz. The beam quality factors of pulse burst laser at 31.1 kHz are measured to be Mx2=1.5 and My2 =1.7 by using the travelling knife-edge method.

A compact pulse burst laser with YAG/Nd:YAG/Cr4+:YAG composite crystal

In this paper, a LD end-pumped passively Q-switched YAG/Nd:YAG/Cr4+:YAG pulse burst 1064nm laser is demonstrated. The output performance of pulse burst laser is optimized by using different output couplers. A pulse burst with 11 pulses under the pump duration of 1ms is obtained by using an output mirror with T=30%. The minimum pulse width is shortened to be 1.7ns with a pulse energy of 210μJ. The highest peak power in YAG/Nd:YAG/Cr4+:YAG pulse burst laser is estimated to be ∼123.5kW.

Effect of a codoped interface layer on passively Q-switched laser performance of composite crystals.

By using combinations of appropriate laser crystals, we simulated a Yb:YAG/Cr⁴⁺:YAG composite crystal with a Cr,Yb:YAG interface layer. The effect of the Cr,Yb:YAG interface layer on the laser performance of the Yb:YAG/Cr⁴⁺:YAG composite crystal has been investigated for the first time to our best knowledge. The formation of the Cr,Yb:YAG interface layer in the Yb:YAG/Cr⁴⁺:YAG composite crystal has a negative impact on average output power, optical efficiency, as well as single pulse energy and peak power. In addition, the Cr,Yb:YAG interface layer also leads to strong mode competition, resulting in the decrease of the longitudinal mode number, the widening of longitudinal mode separations, and the poor stability of laser pulse trains. The results of this study are of theoretical and practical importance to develop novel Yb:YAG/Cr⁴⁺:YAG composite crystals that could be used to obtain laser pulses with high peak power and high optical efficiency.

Pump beam waist-dependent pulse energy generation in Nd:YAG/Cr4+:YAG passively Q-switched microchip laser

The incident pump beam waist-dependent pulse energy generation in Nd:YAG/Cr4+:YAG composite crystal passively Q-switched microchip laser has been investigated experimentally and theoretically by moving the Nd:YAG/Cr4+:YAG composite crystal along the pump beam direction. Highest pulse energy of 0.4 mJ has been generated when the Nd:YAG/Cr4+:YAG composite crystal is moved about 6 mm away from the focused pump beam waist. Laser pulses with pulse width of 1.7 ns and peak power of over 235 kW have been achieved. The theoretically calculated effective laser beam area at different positions of Nd:YAG/Cr4+:YAG composite crystal along the pump beam direction is in good agreement with the experimental results. The highest peak power can be generated by adjusting the pump beam waist incident on the Nd:YAG/Cr4+:YAG composite crystal to optimize the effective laser beam area in passively Q-switched microchip laser.

Compact passively Q-switched Raman laser at 1176 nm and yellow laser at 588 nm using Nd3+:YAG/Cr4+:YAG composite crystal

Compact passively Q-switched YVO4 first Stokes Raman laser and its frequency doubling laser were reported by using Nd3+:YAG/Cr4+:YAG composite crystal for what is believed to be the first time. Nanosecond lasers at 1176 and 588 nm were obtained. At the incident pump power of 7.84 W, the average output power at 1176 nm was 423 mW with a pulse width of 1.32 ns and the pulse repetition frequency (PRF) of 13.7 kHz. By applying a KTP crystal, an intracavity second harmonic generation (SHG) laser at 588 nm also was realized. With an incident pump power of 8.95 W, we obtained 105.3 mW average output power of a yellow laser corresponding to the pulse width of 4.95 ns and the PRF of 10.75 kHz. In addition, the composite crystal efficiently compacted the resonant cavity.

Passively Q-switched microchip lasers based on Yb:YAG/Cr4+:YAG composite crystal

Efficient passively Q-switched microchip laser based on Yb:YAG/Cr4+:YAG composite crystal has been demonstrated under high brightness single-emitter laser-diode pumping. Maximum average output power of 1.5W was obtained when the absorbed pump power was 3.65W, the corresponding optical-to-optical efficiency was over 41%. The slope efficiency was 52.3%. The effect of the cavity length on the performance of Yb:YAG/Cr4+:YAG composite crystal passively Q-switched microchip lasers was investigated. Laser pulses at 1030nm with pulse width of 466ps and peak power of 91kW were achieved with cavity length of 1.7mm, while laser pulses with pulse width of 665ps and peak power of 79kW were obtained with cavity length of 3.7mm.

The study of green laser performances by using composite crystals of different initial transmissions

This paper reported a passively Q-switched green laser of LD pumped linear cavity structure by using Nd:YAG/Cr4+:YAG composite crystal and the type II phase matching KTP crystal. The dependence of average output power, pulse width and pulse repetition rate on pump power at different initial transmissions of Cr4+:YAG were measured and analyzed. With Cr4+:YAG of 80% initial transmission, under pump power of 13.97W, the output average power is up to 681mW, with pulse width of 200ns and pulse repetition rate of 9.1kHz. The laser operates in a fundamental mode.

High Average Power, Compact Passively Q-Switched 532 nm Green Laser on Nd:YAG/Cr4+:YAG Composite Crystal

We design a passively Q-switched intracavity frequency-doubled 532 nm laser using Nd:YAG/Cr4+:YAG composite crystal and type II phase matching KTP crystal. Under 13.97 W pump power, the average output power of the laser elaborated is up to 681 mW, with 200 ns pulse width and 9.1 kHz pulse repetition rate.

High-Power passively Q-switched 532 nm green laser by using Nd:YAG/Cr4+:YAG composite crystal

This paper reported a passively Q-switched 532 nm green laser of LD pumped V cavity structure by using Nd:YAG/Cr4+:YAG composite crystal and the type II phase matching KTP crystal. Under 19.4 W pump power, the average power of the laser pulse up to 1.83 W, with the pulse width of 93.2 ns and repetition frequency of 9.1 kHz.

A thermally-insensitive passively Q-switched Cr 4+:YAG/Nd:YAG laser

A passively Q-switched laser with Cr 4+:YAG/Nd:YAG composite crystal using a corner cube prism cavity has been realized, in which the corner cube prism is the key element as it aids the compensation of the thermal lens effect of laser crystal. Compared with plane–plane mirror cavities under the same conditions, the stability of the laser performance using the corner cube prism cavity was improved remarkably over temperatures ranging from −40 to 65 °C. The decrease of Nd:YAG stimulated emission cross section with temperature was considered to be the main reason for the increase of average output pulse energy under the same cycle for the two different cavities when the ambient temperature changed −40 to 65 °C. The mode properties produced by the prism cavity were analyzed, and the theoretical results were verified by experimental observations.

1.3-ns pulse, compact passively Q-switched microchip green laser by Nd:YAG/Cr4+:YAG composite crystal

In this article, a diode-end-pumped passively Q-switched extra-cavity frequency doubled micro-type green laser by Nd:YAG/Cr4+:YAG composite crystal was demonstrated. The dependence of the average out power, pulse width and pulse repetition rate on incident pump power were measured. Under the pump power of 14 W, the minimum pulse width of 1.3 ns with repetition rate of 68.0 kHz was obtained, corresponding single-pulse energy of 8.8 μJ and peak power of 6.7 kW.

Single diode-pumped, 1.7 ns microchip laser by Nd:YAG/Cr4+:YAG composite crystal

A single diode-pumped passively Q-switched composite Nd:YAG/Cr4+:YAG laser, which cavity mirrors were deposited directly onto the crystal, was demonstrated in this paper. At the incident power of 2.75 W, the maximum average output power of 365 mW and the shortest pulse width of 1.7 ns were obtained, corresponding the repetition rate of 14.6 kHz. The single-pulse energy and the peak power were estimated to be 25 μJ and 14 kW, respectively. The corresponding optical-optical conversion efficiency was 13.3%.

LD bar corner-pumped TEM_00 CW composite Nd:YAG laser

Ray-tracing algorithm was used to simulate the pump absorption efficiency and pump absorption distribution of LD corner-pumped laser with different parameters of Nd:YAG composite slab crystal. Resonator experiment was performed to suppress the oscillation of higher-order modes and realize TEM(00) operation. Experiment results showed that the output power was 11.94 W with an optical-optical efficiency of over 26%, and the M2 factors of beam quality at width and thickness directions were 1.18 and 1.34, respectively. It has been proven that the corner-pumped configuration could obtain laser output with good beam quality as a result of high pump efficiency and good pump uniformity.

2 ns-pulse, compact and reliable microchip lasers by Nd:YAG/Cr4+ YAG composite crystal

A compact diode-end-pumped passively Q-switched composite Nd:YAG/Cr4+:YAG laser was demonstrated in this paper. At the incident pump power of 11.8 W, the shortest pulse width of 2.05 ns was obtained, corresponding to average output power of 1.15 W and repetition rate of 17.1 kHz. The single-pulse energy and peak power were estimated to be 67.3 μJ and 32.8 kW, respectively.