ABSTRACT
Considering the kinetic and fluid dynamic processes in the gain medium, a theoretical model is established to describe the mechanism of thermal-lensing effect in an exciplex pumped Cs vapor laser. The three-dimensional distribution of temperature and index of refraction in the gain medium are depicted. The effective focal length and radius of thermal lens are predicted. Our simulation results show the thermal lens plays a non-negligible role in high-power XPCsLs and can be significantly aggravated in higher wall temperature, buffer pressure and pump intensity. The divergence of laser beam influenced by thermal lens is also made in detail. This model is helpful for in-depth understanding of the thermal-lensing effect in XPALs.
ABSTRACT
A theoretical model is established to describe the kinetic processes and laser mechanism for a nanosecond-pulse exciplex pumped Cs vapor laser (XPCsL). A new simulation method is proposed to solve a set of non-stationary rate equations considering high energy levels and the results of simulation are consistent with the experimental data. The effects of cell temperature, pump energy and buffer gas on the output laser pulses are presented and analyzed in detail, which reveal the unique properties of nanosecond-pulse XPCsL.
ABSTRACT
Considering spectrally resolved absorption and temperature distribution, a physical model is established to describe the laser kinetic and thermodynamic processes of an exciplex pumped Rb vapor laser. A comparison with Carroll's model is made. Influences of pump intensity, temperature, reflectivity of output coupler, and number density of Kr on the performance of CW Rb-Kr XPAL with uniform temperature distribution are calculated and analyzed. Besides, with the heat accumulation considered, the temperature distribution was calculated, and the maximal optical-to-optical efficiency about 5.7% can be achieved at the condition of pump intensity I0 = 5.2 × 1010 W/m2 and flow velocity u = 250 m/s.
ABSTRACT
A physical model combining rate, power propagation, and transient heat conduction equations for diode-pumped alkali vapor lasers (DPAL) is applied to a pulsed Rb-CH4 DPAL, which agrees well with the time evolution of laser power and temperature measured by K absorption spectroscopy. The output feature and temperature rise of a multi-pulse DPAL are also calculated in the time domain, showing that if we energize the pump light when the temperature rise decays to 1/2, rather than 1/e of its maximum, we can increase the duty cycle and obtain more output energy. The repetition rate of >100Hz is high enough to achieve QCW (quasi-continuous-wave) laser pulses.
ABSTRACT
Comprehensive analysis of kinetic and fluid dynamic processes in flowing-gas diode-pumped alkali vapor amplifiers is reported. Taking into account effects of the temperature, the amplified spontaneous emission, the saturation power, the excitation of the alkali atoms to high electronic levels and the ionization, a detailed physical model is established to simulate the output performance of flowing-gas diode-pumped alkali vapor amplifiers. Influences of the flow velocity and the pump power on the amplified power are calculated and analyzed. Comparisons between single and double amplifier, longitudinal and transverse flow are made. Results show that end-pumped cascaded amplifier can provide higher output power under the same total pump power and the cell length, while output powers achieved by single- and double-end pumped, double-side pumped amplifiers with longitudinal or transverse flow have a complicated but valuable relation. Thus the model is extremely helpful for designing high-power flowing-gas diode-pumped alkali vapor amplifiers.
ABSTRACT
Considering the amplified spontaneous emission, the saturation effect and the energy distributions of the incident pump and seed lasers, a physical model is established to describe the kinetic process and the output performance of a four sided diode pumped alkali vapor laser amplifier. According to the experimental parameters of a single-side pumped configuration with a diffuse type hollow cylinder cavity, energy distributions in the cell and influences of several important factors are simulated and analyzed. The model is validated by comparing the simulation result with the experimental data, which shows the model can provide an effective way for designing an efficient diode four-side symmetrically pumped alkali vapor laser amplifier.
ABSTRACT
The kinetic process of Cu(+) UV laser in Ne-CuBr longitudinal pulsed discharge is analyzed and a comprehensive self-consistent physical model is developed. The temporal evolutions of discharge parameters, main particle densities, the electron temperature, and the laser pulse intensity are numerically calculated. The model results illustrate the process of population inversion and the lasing mechanism. The calculations on the influences of the tube radius and Br atoms on the laser output characteristic well explain the experimental results.
