Spectral Characteristics of Miniature Two-Longitudinal-Mode Optically Pumped FIR Laser

With the assumption that the pump source was two-longitudinal-mode, the semiclassical density matrix equation of a three-energy-level system was solved. By means of iteration method, the spectral characteristics of miniature two-longitudinal-mode optically pumped NH₃ far-infrared cavity laser, which was pumped by CO₂-9R(16) line, were calculated numerically. The influences of operating parameters on laser spectrum were studied intensively.     

Construction of a side pumped double-clad fiber using polished couplers

The paper presents a new way of side pumping double-clad fibers. Elaborated asymmetric polished couplers are presented. By using these couplers in pumping power set-ups of double-clad fiber very good pumping efficiency a very good efficiency was attained. The experimental and numerical optimizations of designed couplers are presented.     

An analytical and numerical study of peristaltic transport of a Johnson-Segalman fluid in an endoscope

In the present study, we discuss the peristaltic flow of a Johnson-Segalman fluid in an endoscope. Perturbation, homotopy, and numerical solutions are found for the non-linear differential equation. The comparative study is also made to check the validity of the solutions. The expressions for pressure rise frictional forces, pressure gradient, and stream lines are presented to interpret the behavior of various physical quantities of the Johnson-Segalman fluid.     

The strontium-vapor laser pumping efficiency under running-wave excitation

The effect of the design features of the gas-discharge tube on the processes proceeding in the discharge circuit of a metal-vapor laser has been investigated. The position of electrodes in the gas-discharge tube has been found to significantly affect the processes at work in the discharge circuit and the energy characteristics of the laser. For instance, gas-discharge tubes with electrodes placed in the hot region of the discharge channel are typified by high metastable-population rates at the leading edge of the excitation pulse, whereas with electrodes positioned in cold buffer regions, the leading edge of the voltage pulse across the resistive component of the tube impedance is seen to peak. Conditions for running-wave generation in the active media of lasers on self-terminated transitions of metal atoms and the running-wave use efficiency for laser pumping are discussed, considering a strontium-vapor laser as an illustration. It is shown that the running wave is generated as the result of the breakdown in the anode end of the gas-discharge tube and is maintained by the energy stored in the capacitive component of the impedance of the gas-discharge tube. The lasing pulse duration under running-wave excitation corresponds to the time it takes an ionization wave to propagate from the anode to the cathode of the gas-discharge tube, with pumping efficiency being ~6–8% for a strontium-vapor laser. The average lasing power varies within 10–15% depending on whether the totally reflecting cavity mirror is placed near the anode or the cathode of the tube. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 79–87, December, 2008.     

LD泵浦Cr4+∶YAG被动调Q锁模Nd∶Gd0.42Y0.58VO4激光器

理论和实验研究了LD泵浦Nd∶Gd0.42Y0.58VO4/Cr4+∶YAG被动调Q锁模激光器.在分析Cr4+∶YAG晶体能级结构和调Q锁模物理过程的基础上,通过数值模拟给出了Cr4+∶YAG调Q锁模的参量要求,然后进行了实验验证.实验中Cr4+∶YAG的初始透过率T0分别为86.3%、95%,输出镜的透过率T分别为10%、20%,在其他条件不变的情况下构成四种不同的组合,均实现了激光器的调Q锁模运转.实验结果表明,降低Cr4+∶YAG的初始透过率T0或提高输出镜透过率T有利于获得较好的锁模效果,与理论分析一致.     

Stability of a Laser-diode-pumped Cr~(4 )∶YAG Passively Q-switched Nd~(3 )∶YAG Laser

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The Effect of Incoherent Population Pumping on Squeezing in Resonance Fluorescence

1　ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｓｑｕｅｅｚｅｄｓｔａｔｅｓｏｆｒａｄｉａｔｉｏｎｆｉｅｌｄｈａｓｂｅｅｎｅｘｔｅｎｓｉｖｅｌｙｉｎｖｅｓｔｉｇａｔｅｄ[1].Ｂｏｔｈｔｈｅｏｒｅｔｉｃａｌａｎｄｅｘｐｅｒｉｍｅｎｔａｌｓｔｕｄｉｅｓｈａｖｅｓｈｏｗｎｔｈａｔｔｈｅｒｅｓｏｎａｎｃｅｆｌｕｏｒｅｓｃｅｎｃｅｏｆａｄｒｉｖｅｎａｔｏｍｃａｎｓｅｒｖｅａｓａｓｏｕｒｃｅｏｆｎｏｎｃｌａｓｓｉｃａｌｌｉｇｈｔ.Ｆｏｒｅｘａｍｐｌｅ,ＣａｒｍｉｃｈａｅｌａｎｄＷａｌｌｓ,ａｎｄＫｉｍｂｌｅａｎｄＭａｎｄｅｌ[2…     

Steady state Behaviour of a Three level Ladder Atomic System with Incoherent Population Pumping in a Squeezed Vacuum

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The Effect of Incoherent Population Pumping on Squeezing in Resonance Fluorescence

The effect of incoherent population pumping on the steady-state population inversion and the quadrature squeezing spectra produced in the resonance fluorescence of a two-level atom is investigated. In the presence of incoherent population pumping, the steady-state population inversion is increased for small frequency detuning but is not changed for large frequency detuning. For resonant excitation at low intensities, the weak incoherent pumping degrades the degree of the squeezing and shifts the position of the maximum squeezing; for off-resonant excitation at strong intensities, the weak incoherent pumping hardly changes the squeezing spectra. But when the incoherent pumping is strong the squeezing may be completely destroyed for both cases.     

An apparatus for NMR of laser polarized 129Xe on single crystal surfaces

Due to a lack of at least 2 orders of magnitude in the amount of sample nuclei, single crystal surfaces are out of reach for conventional NMR measurements. Our aim is to prove that highly polarized ¹²⁹Xe provides a technique to overcome this restriction. Therefore an apparatus for polarizing ¹²⁹Xe up to 0.7 by spin transfer from optically pumped Rb has been designed as well as an NMR spectrometer in combination with a UHV chamber with sample cleaning, cooling and characterization abilities and a special manifold of glass stopcocks with a liquid nitrogen cooled trap for dosing nitrogen free polarized Xe into the chamber onto the surface. This revised version was published online in August 2006 with corrections to the Cover Date.