Diode-pumped Nd:YAG laser for precision laser machining

Abstract

Results are presented on a high power, diode-pumped, pulsed Nd:YAG laser for precision laser machining. The laser is an unstable resonator with a graded reflectivity outcoupler, generating a beam with excellent beam quality. The gain medium is a single zig-zag slab, pumped symmetrically by diode arrays. The use of diode arrays minimizes the thermal loading on the slab, and the zig-zag path averages thermal distortions in the zig-zag dimension. Measurements of beam divergence as a function of diode duty-cycle will be presented. Available pulse formats will also be discussed. To date, the laser has produced 720 W at 20% diode duty-cycle with a stable cavity and 550 W at 20% duty cycle with an unstable cavity in close agreement with model predictions. The beam divergence has been measured to be 1.7 times diffraction-limited at 20% duty cycle. The laser has been operated with pulse lengths from 20 μs to 1 ms and is being used to obtain laser processing data, with some results shown.

Spatially and temporally resolved temperature measurements of plasma generated in percussion drilling with a diode-pumped Nd:YAG laser

“…5 Previous work 8 demonstrated that the optimal pulse format for drilling occurs when the laser runs in a ''gain-modulated'' mode, which produces a burst of pulses in a comb-like pattern with the duration of each burst equal to the length of the laserdiode pump pulse. The modulated pulse format used in this experiment consisted of three ''spikes'' per burst; each spike was 75 ns full width half maximum ͑FWHM͒ and individual spikes were separated by 20 s. The burst repetition rate was limited to 3 Hz by the data acquisition rate of the diagnostic apparatus.…”

“…[1][2][3][4][5] However, the current Nd:YAG lasers are inadequate for many applications, due to limitations in average power and beam quality. The newest generation of lasers utilizing diode pumping in a slab geometry offers the prospect of multi-kilowatt ͑average power͒ Nd:YAG systems with focused beams within 2-3 times the diffraction limit.…”

Fabrication of microfluidic mixers and artificial vasculatures using a high-brightness diode-pumped Nd:YAG laser direct write method

“…The detailed characteristics of the laser and its performance are well described elsewhere. 21 With the laser's high beam quality and exceptional brightness, various precision machining procedures have been successfully demonstrated. In this study, the laser was set to operate at its fundamental wavelength of 1064 nm, repetition rate of 200 Hz and pulse width of 150 ms (duty cycle of 3%).…”

“…As such, there are few successful reports on the use of long pulse lasers for silicon micromachining. We overcame the problem of debris buildup by adapting methods of Dauer et al who removed solidified oxide and silicon melt by wet chemical etching in 40% HF for 10 min at a rate of 60 mm min 21 followed by 30% KOH at 70 °C for 10 min at a rate of 30 mm h 21 along the < 100 > plane. [22][23] It was noted that HF only removed silicon oxides while KOH removed any silicon melt created during laser machining and have little effects on the overall design of the microdevices (at most an additional 5 mm due to the KOH etching).…”

Compact and highly stable electro-optic Q-switched laser at 1064 nm based on a composite YAG/Nd:YAG crystal

“…Laser-diode-pumped (LD-pumped) solid-state lasers possess the merits of compact structure, high peak power, narrow pulse width, high conversion efficiency, good beam quality, etc., and are widely used in microprocessing, laser ranging, imaging, and space communication 1 – 7 In the particular field of lidar, high pulse energy is conducive to long-distance detection, narrow pulse width and high repetition rate contribute to high resolution and high sampling rate, and high beam quality and stability are favorable for obtaining clear images of targets 8 . At present, to realize pulsed laser output with high repetition rate, Q-switching is mostly utilized.…”