RESUMO
We report for the first time on a closed-loop cycle narrow linewidth XeF(C-A) blue laser at a repetition rate of up to 10 Hz with each pulse energy of >1 J. A FWHM linewidth of less than 1.5 nm (minimum to 1.1 nm) with a highly stable wavelength centered at 488.3 nm was achieved by employing a polarization-independent custom-designed narrowband optical filter (NBOF) into the cavity. The pulse energy, as well as the repetition rate, to the best of our knowledge, is the highest ever reported in the narrow linewidth XeF(C-A) blue lasers at repetitively-pulsed mode.
RESUMO
Performing complex semantic queries over large-scale distributed media contents is a challenging task for rich media applications. The dynamics and openness of data sources make it uneasy to realize a query scheme that simultaneously achieves precision, scalability, and reliability. In this paper, a novel relation routing scheme (RRS) is proposed by renovating the routing model of Content Centric Network (CCN) for directly querying large-scale semantic media content. By using proper query model and routing mechanism, semantic queries with complex relation constrains from users can be guided towards potential media sources through semantic guider nodes. The scattered and fragmented query results can be integrated on their way back for semantic needs or to avoid duplication. Several new techniques, such as semantic-based naming, incomplete response avoidance, timeout checking, and semantic integration, are developed in this paper to improve the accuracy, efficiency, and practicality of the proposed approach. Both analytical and experimental results show that the proposed scheme is a promising and effective solution for complex semantic queries and integration over large-scale networks.
Assuntos
Semântica , Armazenamento e Recuperação da Informação , Modelos TeóricosRESUMO
A diode-cladding pumped mid-infrared passively Q-switched Er(3+)-doped ZBLAN fiber laser with an average output power of watt-level based on a semiconductor saturable absorber mirror (SESAM) is demonstrated. Stable pulse train was produced at a slope efficiency of 17.8% with respect to launched pump power. The maximum average power of 1.01 W at a repetition rate of 146.3 kHz was achieved with a corresponding pulse energy of 6.9 µJ, from which the maximum peak power was calculated to be 21.9 W. To the best of our knowledge, the average power and the peak power are the highest in 3 µm region passively Q-switched fiber lasers. The influence of gain fiber length on the operation regime of the fiber laser has been investigated in detail.
RESUMO
An optically pumped XeF(C-A) laser with 0.1-1 Hz pulse-repetition mode is demonstrated. The maximum output energy is up to 18.7 J, which corresponds to the conversion efficiency of the stored electrical energy to laser output energy of 0.25%. The laser active medium is optically excited by vacuum-ultraviolet radiation of two single-channel surface discharges initiated along opposite walls of the laser cell. The laser resonator output coupling is 10%, and the initial XeF2 concentration in the active gas mixture is ~1 x 10(17) cm(-3). The duration of the observed laser pulses is 0.8 to 1.2 micros, and the spectral band is 470-500 nm.