Xingshi Zheng

Study on spectral characteristics and operating parameters of optically pumped NH/sub 3/ FIR cavity laser

By solving the density matrix equations of a quantum system and taking into account the multibeam interference characteristics of a Fabry-Perot cavity, the output power density of an optically pumped NH/sub 3/ far-infrared (FIR) cavity laser was calculated by means of the iteration method. Based on the calculations, the spectral characteristics and operating parameters of the laser were studied. Experimentally, by using inductive metallic meshes as reflectors and couplers, a series of FIR cavity lasers with a sample tube of 10, 20, and 100 cm in length were designed and constructed, and the emissions of the NH/sub 3/ cavity lasers pumped by a TEA-CO/sub 2/ laser with a 10R(8) or 9R(16) line were measured. The experimental results were in good agreement with theoretical calculations.

Spikes in Raman spectrum of miniature optically pumped NH3 FIR laser

In this paper, the semiclassical density matrix equation was solved to calculate the spectral characteristics of V2:a--sR(0,0) transition in a miniature optically pumped NH3 far infrared laser (mini-NH3-OPFIRL), which was pumped by CO2-10R(6) line. The results of theoretical calculation showed that the spikes in Raman spectrum of V2:a--sR(0,0) would appear when the operating NH3 gas pressure was higher than a certain critical value or pumping power density was lower than a certain critical value, which was caused by Raman processes interaction of AC-Stark splitting. In our experiment, 298 µm FIR spetral line of a--sR(0,0) pumped by a TEA-CO2 laser with 10R(6) line was observed but the spikes could not be observed owing to the limitation of the resolution of the F-P interferometer.

Interaction of multi-raman-processes in miniature optically pumped NH3 fir laser

The principle of Raman gain superposition was introduced to the theory of multi-Raman- processes interaction. Spectral characteristics of Raman lines from miniature NH3-optically pumped FiR lasers were studied and measured.

Operating parameter optimization of optically pumped CH3OH far-infrared laser

By solving the density matrix equations of a quantum system, the output power intensity of an optically pumped CH3OH FIR laser (CH3OH-OPFIRL) was calculated by means of iteration method, and the spectral characteristics were got. Base on the calculation, optimization of operating parameters including operating gas pressure, pumped power and output coupling coefficient of the CH3OH cavity laser were systematically studied. Experimental, a series of FIR emissions of the CH3OH cavity laser pumped by TEA-CO2 laser with 9P(16) line were measured. The experimental results were in good agreement with theoretical calculations.

Grazing-incidence far-infrared gas laser

First realization of a grazing-incidence gas laser is reported. For this purpose an optically pumped 496 μm CH3F laser is equipped with a cavity consisting of a diffraction grating and a resonant mirror. The observed resonances are interpreted with an approximative theory and related to distributed feedback.

Experimental study on miniature pulsed CH3OH far-infrared laser

Using a grating tuned TEA-CO2 laser with 9P(16) line to pump a 10cm or 20cm long miniature Fabry-Perot cavity CH3OH laser, pulsed far infrared(FIR) lines of 570.6um and 918um wavelengths were observed, the latter is a new line. Operation performance and spectral characteristics of the miniature CH3OH laser were studied.

The tuning characteristics of optically pumped fir cavity laser

Based on the quantum mechanics theory of density matrix and the principle of multiple-beam interference, the tuning characteristics of optically pumped NH3 FIR lasers were studied. A series of metallic mesh Fabry-Perot cavity lasers with sample tubes of 10cm, 20cm and 100cm in length were constructed and operated successfully, and the FIR laser spectra of the NH3 cavity lasers pumped by a TEA-CO2 laser were measured.

Study of miniature optically pumped NH3 fir cavity laser

A miniature NH3 molecule FIR cavity laser of 15cm in length pumped by a TEA CO2 laser was built. The spectral characteristics of the cavity laser and the optimum operating parameters were studied.

Further study on interaction enhancement of Raman processes in miniature OPFIRL

The interaction of Raman processes leads to the change of the properties of a miniature NH3-OPFIRL much, such as lasing efficiency, spectral characteristics and optimum operating gas pressure. The influences on FIR spectrum and optimum operating gas pressure of such system were studied experimentally and theoretically.

The Spectrum of Ground-State Reversed Transition of CH3OH Far-Infrared Laser

Using the CH3OH molecular energy levels data base management program, we deduced that when a CH3OH laser pumped by CO2-9P(16) line, there should be a FIR laser line of 918μm wavelength, which corresponding to a transition in ground-state reversed three-level energy system. For the first time, the spectra of ground-state reversed three-level system transitions were calculated by solving the density matrix equations, and the spectrum characteristics of 918μm line were studied. Experimentally, the CH3OH FIR laser line of 918μm wavelength was obtained by pumping with a TEA-CO2 laser. The experimental results were in good agreement with the theoretical calculations.