Electro Scientific Industries, Inc.

Wensheng Ren

Xiaoyuan Peng

Brian W Baird

David Martin Hemenway

Embodiments of laser systems advantageously use pulsed optical fiber-based laser source () output, the temporal pulse profile of which may be programmed to assume a range of pulse shapes. Pulsed fiber lasers are subject to peak power limits to prevent an onset of undesirable nonlinear effects; therefore, the laser output power of these devices is subsequently amplified in a diode-pumped solid state photonic power amplifier (DPSS-PA) (). The DPSS PA provides for amplification of the desirable low peak power output of a pulsed fiber master oscillator power amplifier () to much higher peak power levels and thereby also effectively increases the available energy per pulse at a specified pulse repetition frequency. The combination of the pulsed fiber master oscillator power amplifier and the diode-pumped solid state power amplifier is referred to as a tandem solid state photonic amplifier ().

Tandem photonic amplifier

High-power, diode-pumped solid state (DPSS) pulsed lasers are preferred for applications such as micromachining, via drilling of integrated circuits, and ultraviolet (UV) conversion. Nd:YVO(vanadate) lasers are good candidates for high power applications because they feature a high energy absorption coefficient over a wide bandwidth of pumping wavelengths. However, vanadate has poor thermo-mechanical properties, in that the material is stiff and fractures easily when thermally stressed. By optimizing laser parameters and selecting pumping wavelengths and doping a concentration of the gain medium to control the absorption coefficient less than 2 cmsuch as the pumping wavelength between about 910 nm and about 920 nm, a doped vanadate laser may be enhanced to produce as much as 100 W of output power without fracturing the crystal material, while delivering a 40% reduction in thermal lensing.

Laser with gain medium suppressing higher order modes to provide lasing output with high beam quality

Anisotropic crystals such as Nd:YVO, Nd:YLF, and Nd:GdVOhave become preferred gain materials for many laser applications. The anisotropic gain medium without ancillary compensation ensures there is no degradation of laser modes when passing through the gain medium. An optical power amplifier that incorporates an anisotropic gain medium achieves power scaling with multiple passes while also maintaining good mode matching between the laser and the pump during each pass. Preferred embodiments implement for multiple passes of a seed laser beam through an anisotropic gain medium with substantially zero angular beam displacement during each pass. The multi-pass system provides an economical, reliable method of achieving high TEMpower to meet the demands of micromachining, via drilling, and harmonic conversion applications.

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Beaverton, OR, United States of America

Wensheng Ren