YAG Zigzag Slab Laser Research Articles

Wavefront improvement in an end-pumped high-power Nd:YAG zigzag slab laser.

Techniques for wavefront improvement in an end-pumped Nd:YAG zigzag slab laser amplifier were proposed and demonstrated experimentally. First, a study on the contact materials was conducted to improve the heat transfer between the slab and cooling blocks and to increase the cooling uniformity. Among many attempts, only the use of silicon oil showed an improvement in the wavefront. Thus, the appropriate silicone oil was applied to the amplifier as a contact material. In addition, the wavefront compensation method using a glass rod array was also applied to the amplifier. A very low wavefront distortion was obtained through the use of a silicone-oil contact and glass rod array. The variance of the optical path difference for the entire beam height was 3.87 μm at a pump power of 10.6 kW, and that for the 80% section was 1.69 μm. The output power from the oscillator was 3.88 kW, which means the maximum output extracted from the amplifier at a pump power of 10.6 kW.

Design of pump beam delivering optical system and doped YAG length to minimize the wavefront distortion in a high-power Nd:YAG zigzag slab laser

An end-pumped high-power Nd:YAG zigzag slab continuous wave laser amplifier was designed through a computational simulation to minimize the wavefront distortion of the output laser beam. The pump beam delivering optical system was optimized with an acylindrical slow-axis lens to lower the distortion of nonzigzag propagation for the beam height axis. In addition, the wavefront distortion of the zigzag propagation for the beam width axis was studied and minimized by slightly changing the doped YAG length. The simulation results of the final design showed a peak-to-valley optical phase difference (OPDP−V) of 0.83 μm and a very low beam quality of 1.19× diffraction limit, even with a total pump power of 10 kW.

Simulation of the wavefront distortion and beam quality for a high-power zigzag slab laser

A simulation method of the beam quality for a high-power zigzag slab laser has been developed. This method can predict the wavefront distortion and beam quality for various optical arrangements and optimize the design effectively. A Nd:YAG zigzag slab laser amplifier was designed as an application. The optimized design shows a beam quality of 1.20 corresponding to the minimized wavefront distortion with a peak-to-valley of 0.568μm and root mean square of 0.115μm even under high-power operation with a total pump power of 14kW. Although there are some effects other than the optical design error that incur wavefront distortions, this method can help to determine the first optical design of the zigzag slab laser without the need for many experimental studies.

High efficiency and high-energy intra-cavity beam shaping laser

We present a technology of intra-cavity laser beam shaping with theory and experiment to obtain a flat-top-like beam with high-pulse energy. A radial birefringent element (RBE) was used in a crossed Porro prism polarization output coupling resonator to modulate the phase delay radially. The reflectively of a polarizer used as an output mirror was variable radially. A flat-top-like beam with 72.5 mJ, 11 ns at 20 Hz was achieved by a side-pumped Nd:YAG zigzag slab laser, and the optical-to-optical conversion efficiency was 17.3%.

4350W quasi-continuous-wave operation of a diode face-pumped ceramic Nd:YAG slab laser

Abstract A high efficiency and high power laser diode (LD) face-pumped quasi-continuous-wave (QCW) ceramic Nd:YAG zigzag slab laser is demonstrated. The shape of the LD pump beam is optimized to ensure that the pump size is well matched with the ceramic slab and to improve the uniformity of the intensity distribution along the length and width direction of the ceramic slab. Meanwhile, an efficient cooling technique is adopted to obtain the uniform temperature distribution inside the ceramic slab. Under the LD pump power of 9.98 kW, a maximum average output power of 4.35 kW at 1064 nm is demonstrated at a pulse repetition frequency of 400 Hz, corresponding to an optical to optical conversion efficiency of 43.6%. To the best of our knowledge, this is the highest output power as well as the highest conversion efficiency reported for face-pumped QCW ceramic Nd:YAG single slab laser.

传导冷却的全固态zigzag板条激光器

A diode pumped, Q-switched Nd:YAG zigzag slab laser is developed using passive conduction cooling. Flat-flat and unstable resonators are adopted in this experiment. The 150-mJ multi-mode and 100-mJ single-mode laser outputs with pulse width of 10 ns are achieved, corresponding to optical efficiencies of 19% and 13%, respectively. The experimental result demonstrates that the laser has the property of compact structure, high efficiency, reliability, and high beam quality. The design of laser has a potential application in space environment.

High efficiency TEM 00 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 ( M 2) in x and y directions equal to 32 and 8, respectively. TEM 00 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 TEM 00 mode operation. In passive Q-switching with Cr 4+: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.

Q-switched rate equations for diode side-pumped slab and zigzag slab lasers including Gaussian beam shapes

A set of rate equations accounting for the transverse spatial distributions of both the laser mode and inversion density is developed for side-pumped Q-switched oscillators. The equations can be reduced to a simple form by assuming a Gaussian laser mode, a one-dimensional Gaussian pump beam and a few additional basic assumptions, allowing for rapid numerical solution. The derived spatial rate equations are then used to model an experimentally well-characterized Nd/sup +3/:YAG zigzag slab laser to demonstrate their simplicity and accuracy in predicting oscillator performance.

Present Status of Laser-Diode Pumped High-Power Nd:YAG Lasers.

The present status of laser-diode (LD) pumped high-power Nd: YAG lasers at 1.06μm is reviewed. With a side-pumped rod geometry, an output of of 1.25J per pulse is demonstrated. The LD-end-pumped Nd: YAG laser can produce an output power of CW 60W in a near-diffraction-limited beam. A one Joule per Q-switched pulse LD-pumped Nd: YAG zigzag-slab laser is constructed. A 1-kW average-power LD array-pumped folded zigzag-slab Nd: YAG laser is demonstrated at 2.25 kHz. A phase conjugated LD-pumped Nd: YAG MOPA laser architecture is proposed to have a 1 kW average power in a near-diffraction-limited beam. An LD pumped Nd: YAG regenerative amplifier is achieved simultaneously with a high gain (71dB) and a high energy extraction efficiency (48%) .