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We report a unidirectional single-longitudinal-mode Ho:YLF ring laser. An acousto-optic modulator and two half-wave plates were used to enforce the Ho:YLF ring laser in a unidirectional operation. The single-longitudinal-mode output power could reach 3.73 W successfully when the incident pump power was 16.4 W. The corresponding slope efficiency was 27.1%. The wavelength of the single-longitudinal-mode Ho:YLF ring laser was 2063.8 nm. The M 2 factor was 1.12. The results illustrated that the single-longitudinal-mode output power could be further enhanced by increasing the radio frequency power of the acousto-optic modulator. [ABSTRACT FROM AUTHOR]

We have demonstrated an acousto-optical cavity dumping Tm:YAG ceramic laser at a wavelength of 2012.6 nm. The pulses were coupled out of the cavity by the lateral surface when radio frequency was added into the acousto-optical modulator. The minimum pulse width of the cavity dumped Tm:YAG ceramic laser is 31 ns, corresponded with an output power of 180 mW and a repetition rate of 200 kHz. In addition, the unsmooth pulse shape of the cavity dumped Tm:YAG ceramic laser was numerically calculated. [ABSTRACT FROM AUTHOR]

Abstract: Open-cell foams have wide applications in structural components, energy adsorption, heat transfer, sound insulation, and so on. When their in-service temperature is high, time dependent creep may become significant. To investigate the secondary creep of low density foams under multiaxial loading, three-dimensional (3D) finite element (FE) Voronoi models are developed. The effects of relative density, temperature, cell irregularity, and stress state on the uniaxial creep are explored. By taking the mass at strut nodes into account, the creep foam model by Gibson and Ashby (Cellular Solids: Structure and Properties, 2nd ed., Cambridge University Press, Cambridge, UK, 1997) is modified. Obtained results show that the uniaxial secondary foam creep rate predicted by the FE simulations can be well captured by the modified creep model. For multiaxial secondary creep, a phenomenological elastoplastic constitutive model is extended to include the rate effect into the creep response of 3D Voronoi foams. Again, the model predictions agree well with the FE results. [Copyright &y& Elsevier]