Performance Of High-power Laser Research Articles

Optimized monolithic edge-cladding glass for N31-type Nd-doped high power laser glass

In this paper, six edge-cladding glasses are prepared and analyzed, which are designed to clad the elliptical disk of N31-type Nd-doped phosphate laser glass by monolithic edge-cladding technique. The transition temperatures, soften temperatures, thermal expansion coefficients, high temperature viscosities and refractive indices of the prepared edge-cladding glasses are determined, which must be consistent with these parameters of N31 glass as possible. The residual stresses and residual reflectivities are determined for the cladded N31 elliptical disks and slab samples, which are the most important parameters for the monolithic edge-cladding technique and must be as low as possible to meet the index requirements for high power laser applications. The interface bubbles, edge-cladding interface and the controllability of divalent Cu2+ ions are also discussed. By the optimized edge-cladding glass, it is verified that the elliptical disk of N31-type Nd-doped phosphate laser glass can be successfully cladded by the optimized monolithic edge-cladding glass, which can be utilized securely in a strong liquid cooling to pursue a better high-power laser performance with a higher laser shot rate.

On Yb:CaF_2 and Yb:SrF_2: review of spectroscopic and thermal properties and their impact on femtosecond and high power laser performance [Invited

We present an overview of laser results we obtained with Yb-doped calcium fluoride and its isotype strontium fluoride. In order to study the laser performance in femtosecond and high power regimes, spectral and thermal properties are first discussed including the potential of these crystals at room and cryogenic temperatures. Experimental demonstrations of high-power and ultrashort pulse oscillators and amplifiers are presented and analyzed.

Applications and performance of high power lasers and in the battlefield

This paper reviews the status and applications of a defensive weapon based on high power lasers, in the battlefield. Laser weapon is a novel concept which utilizes high power laser beam to traverse the distance into incoming objects at a speed of light, and then, destroy or disable it. Various types of lasers and configurations will be discussed in this review including gas lasers, solid state lasers, fiber lasers and the free-electron laser. We will discuss various configurations such as airborne laser (ABL), diode pumped crystals and disk lasers as well as heat-capacity lasers. Recent applications of ultrafast solid state lasers for non-lethal or low collateral damage applications will be presented.

Non-sinusoidal phase modulations for improved performance of high power lasers

Spectral broadening is required on high power lasers to avoid Stimulated Brillouin Scattering in the laser chains and to smooth the focal spot. Up to now, spectral broadening has been obtained by sinusoidal phase modulations. However, it leads to non-homogeneous spectra, which is not optimal. In this paper we show that, thanks to non-sinusoidal phase modulations, performance of high power lasers may be enhanced. Furthermore, we demonstrate theoretically and experimentally that adjusting non-sinusoidal phase modulations may be almost as simple as adjusting sinusoidal ones.

The Influence of laser cavity gaseous impurities on the performance of an industrial CO2 laser

Contamination in the cavities of high power industrial CO2 lasers is a cause of laser performance degradation. Such degradation can result in laser downtime and significant loss of productivity. The laser cavity gas supply can contribute to this contamination, but there is confusion about the level of gas impurity concentration which can cause a degradation process. The overall objective of this investigation was to study the effects of cavity gas contaminants on the performance of an industrial fast‐axial‐flow CO2 laser. A 3 kW fast‐axial‐flow CO2 laser operated for 2100 h prior to this investigation was employed in a series of gas contamination experiments. The operating power was selected as 1500 W. After cleaning the laser cavity, the absorptivities of output coupler and rear mirror were measured after laser operation using both ultra‐high‐purity laser cavity gases (99.999%) and premixed contaminated helium (100 ppm, 1000 ppm and 5000 ppm for C3H8, C2H4, CH4 and O2). The output powers were also measured. The results show that increased absorptivities in the output coupler were observed with both hydrocarbon and oxygen impurities compared to those with ultra‐high‐purity gases (99.999%). The increased absorptivities in the output coupler and rear mirror seem to correlate with the total carbon content in the laser cavity due to the gaseous hydrocarbon impurities. Deposition on the surfaces of corner mirrors were identified as carbon using energy dispersive electron spectroscopy analysis. Several flakes of deposited carbons were also identified on the surface of the NaCl window inside the resonator after operating the laser using 5000 ppm propane in helium. 1000 ppm oxygen in the laser gas mixture resulted in an increase of 1.4 % in the output power (4.8 % for 5000 ppm oxygen). 1000 ppm of propane resulted in a decrease of 17 % in the output power. A 44.8 % of power drop was observed when using 5000 ppm propane. The negative effect of contamination (especially hydrocarbon) on high power laser performance was demonstrated.