Power Of Solid-state Laser Research Articles

Evaluation of the effect of local gas flows on keyhole geometry by means of a half-section setup

Increasing beam power of solid-state lasers enables high welding speeds for laser welding processes. However, increasing welding speeds lead to imperfections, especially spatter formation while processing high-alloy steels. A recent and novel approach to reduce the spatter formation is the utilization of a local gas flow to manipulate the keyhole pressure balance beneficially. To get a better understanding of the effect of the gas flow on the keyhole and its geometry during deep penetration welding, a half-section setup was developed. The laser beam was positioned partially on a glass plate and the metal sheet to provide an insight into the processing zone by means of high-speed recordings. Thus, it was possible to measure the keyhole geometry and to quantify the effect of different welding speeds and gas flows on keyhole length for full penetration welds.

Fundamental Limits to Mode-Locked Lasers: Toward Terawatt Peak Powers

Most mode-locked solid-state lasers are based on soliton solutions of the cubic Ginzburg-Landau equation. Their performance is close to theoretical limits, and new design paradigms will be needed if solid-state systems are to continue to improve at their historically aggressive rates. Through comprehensive analysis of the interplay of group-velocity dispersion, nonlinear refraction, spectral filtering, and saturable absorption, we identify the factors that fundamentally limit the achievable peak power of solid-state lasers. Numerical calculations that accurately model existing solid-state lasers are used to assess new designs. In particular, we focus on normal-dispersion cavities, which support dissipative solitons. The calculations reveal that the gain bandwidth, modulation depth of the saturable absorber, and nonlinear phase accumulation present the primary limitations to the peak power. We assess these limitations in Ti:sapphire, Yb:KGW, and thin-disk oscillators. Guidelines for the optimum designs are presented, and we show that dissipative soliton pulse-shaping in cavities with net normal dispersion can fundamentally allow performance improvements of several orders of magnitude. High-performance oscillators should offer low-noise, low-cost alternatives to some current amplifier-based systems.

Study of the charging circuit of a pulsed solid-state laser power supply: A new concept of high charging efficiency and realization

Based on physical theory, a new concept for achieving high efficiency in a solid-state laser power supply charging circuit is first introduced in this paper that is, from the fact that when an electron from a power source enters the energy storage capacitor, a potential drop would occur in this process. This potential drop is the essence of the energy loss in a charging circuit. If the potential drop is small, or even negligible, power supply with a higher efficiency can be achieved. According to this design theory, a highly efficient charging circuit can be obtained if a power source with a single continuous increased voltage slightly higher than that of the energy storage capacitor is employed. With the use of this proposed technique, a prototype of a pulsed YAG laser power supply with high charging efficiency and high voltage charging precision is implemented. The design idea and the experimental results are described and discussed in detail.

Effect of a Photonic Band Gap on the Threshold and Output Power of Solid-State Lasers and Light-Emitting Diodes

We present results for the operation of a three-level solid-state laser both with normal and with completely suppressed spontaneous emission between the lasing levels. The output power difference in these two cases drops as the pump rate is increased above threshold and is not greatly different at higher powers. The threshold pump power, although typically reduced by an order of magnitude, is not zero and our results thus throw further light on the concept of ``thresholdless'' lasing. The theory is also applicable to light-emitting diodes and amplifiers which function on the same principles as a laser.

Optical Design of a Laser System for Nuclear Fusion Research

High power laser improvements, high quality aspheric lenses, and sharp focusing on a solid deuterium target enable us to get numerous nuclear fusion reactions inside the deuterium plasma. Since Maiman successfully built the first light amplifier in 1960 [Nature 187, 493 (1960)] and Terhune performed air breakdown experiments in 1962 ["Optical Third Harmonic Generation," Comptes rendus de la 3ème Conférence Internationale d'Electronique Quantique, Paris, 11-15 février 1963, P. Grivet and N. Bloembergen, Eds. (Dunod, Paris, 1964), pp. 1559-15761, the laser has been thought of as a valuable energy source for fusion devices. Now a kind of race has started toward high temperature plasmas created by powerful lasers. However, the peak power of solid state laser is limited by glass damage, pump efficiences, and unwanted effects such as superradiance. So it is necessary to improve all the optical properties of the laser and the focusing of the lens on the target. In this paper, requirements for fusion implying a very high flux will be stated. Successive optical designs will be described together with measurement methods, and the contribution of optical improvements to the occurrence of nuclear fusion reaction in deuterium targets will be evaluated.