Cu HyBrID laser kinetics : optimization of HBr partial pressure and buffer-gas flow rate

A detailed investigation into the dependence of the densities of the principal plasma species in the laser discharge on the buffer-gas operating parameters is reported. Simple expressions for the densities of the Cu, Br, and H species are derived by considering their major mechanisms for production and loss. These predict that the atomic Cu and Br densities are proportional to the HBr mass flow rate, whereas the density of H species (i.e., H and H₂) is proportional to the added HBr partial pressure. The theory agrees well with “Hook” method measurements of Cu density in a 25-mm bore diameter device; the Cu density increases approximately in proportion to the HBr mass flow rate, whereas it depends only weakly on the HBr partial pressure. Measurements of the fraction of Cu atoms excited by the discharge pulse, the rate of regrowth of the ground-state Cu density during the inter-pulse period, and the pre-pulse plasma impedance, are also explained in accordance with the theory. The results show that the plasma conditions for maximum laser output, which are remarkably similar to those of other “halogen enhanced” Cu lasers, can be achieved more directly by adjusting the overall buffer flow rate with the partial pressure of the added HBr fixed at 1–2 mbar. The theory is also useful for predicting optimum buffer-gas conditions for a wide range of Cu HyBrID laser dimensions and operating conditions.8 page(s

Intrinsic optical properties of diamond

34 page(s

Side-pumped crystalline Raman laser

A crystalline Raman laser is pumped at 90° to the Raman laser axis by a single pass from a line-focused 532 nm pump laser of pulse duration 10 ns. The Raman laser threshold was 6:1 mJ, and at 12 mJ pump energy, a maximum output energy of 2:7 mJ was obtained with a slope efficiency of 46%. The threshold pump intensity is within a factor of 2 of the same device when end-pumped. The results highlight significant potential for coherent beam conversion and combination with enhanced degrees of flexibility and increased power. © 2011 Optical Society of America.3 page(s

The outlook for diamond in Raman laser applications

Efficient and practical Raman lasers based on single crystal diamond are now realizable owing to the availability of optical quality crystals grown by chemical vapour deposition (CVD). In this paper, the performance characteristics of CVD-diamond Raman lasers are summarized and the results compared to those for more established Raman materials. The outlook for diamond Raman lasers is discussed and key challenges for material development highlighted.12 page(s

Recent progress in diamond raman lasers

In its relatively short history as a Raman laser material, CVD diamond has already demonstrated to be a forerunner in performance. Yet the more outstanding properties of the material such as its high thermal conductivity and wide transmission range remain largely unexploited. This paper summarizes the recent studies aimed to extend diamond laser capability beyond that readily achievable using other materials, focusing on in particular diamond Raman lasers in the ultraviolet, infrared and at high average powers.12 page(s

Mode locking using stimulated Raman scattering

Recent experiments have shown that the simple addition of a length of Raman-shifting fibre in the cavity of a cw-pumped fibre laser can cause the laser to generate a stable train of pulses [Zhao and Jackson, Opt. Lett., 31 751 (2006)]. We show using a numerical model that this behavior is a new type of mode locking, driven by backward stimulated Raman scattering. This mode locking mechanism could also be applied to crystalline Raman laser systems to create a novel picosecond oscillator.6 page(s

Compact and efficient kinetically enhanced copper-vapor laser of high (100-W) average power

We report on severalfold increases in the output power of kinetically enhanced copper-vapor lasers operating in a regime of high specific input power and reduced tube insulation. Three laser tubes, of length 1 m and bore diameters 17.5, 25, and 32 mm, were investigated at constant input power. Output power of 104 W at 1.4% wall-plug efficiency was obtained for the largest tube. When the bore diameter was decreased to 17.5 mm, the output power and efficiency remained high (90 W at 1.0% efficiency), whereas the specific output power increased threefold. The output powers were as much as fivefold higher than those of previous small-scale (i.e., <25 mm -diameter) copper lasers of any type.3 page(s