共查询到18条相似文献,搜索用时 109 毫秒
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本文提出一种不用缓冲气体而用涂层泡的Rb87激射器的试验方案。给出了满足激射振荡要求的特定的涂层泡的设计,同时,讨论了激射器的振荡条件及予期所能获得的短期频率稳定度。最后,指出该激射器可能发展为长、短稳兼优的频标。 相似文献
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研究了利用相干陷落方法在单原子微激射器中产生具有四阶压缩和振幅平方压缩性质的稳态腔场.结果表明,在目前微激射器实验的腔损条件下,如果注入腔中的原子初始处于相干态,只要原子束的通量适当大,当原子在腔中的飞行时间满足陷落条件时,腔场可进入相干陷落态,此时腔场呈现稳定的四阶压缩和振幅平方压缩性质
关键词: 相似文献
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报道了利用垂直外腔面发射激光器(Vertical external cavity surface emitting laser,VECSEL)的增益谱与腔模的大失配设计实现VECSEL双波长同时激射的方法,设计了稳定的振荡腔结构,理论预测了这种VECSEL的三种工作状态并进行了实验验证。随着VECSEL泵浦功率增加,增益芯片内部工作温度逐步升高,VECSEL依次出现带边波长激射、双波长激射及腔模波长激射三种工作状态。最初VECSEL的激射波长位于带边模式决定的激光波长(952.7 nm),随着泵浦功率增加,增益芯片热效应增强,腔模波长与带边波长出现模式竞争,此后出现双波长激射现象。双波长峰值强度接近时VECSEL激光输出功率达到359 mW,激光波长分别位于954.2 nm和1001.2 nm,在该位置附近VECSEL的输出功率曲线呈现明显的二次阈值现象。当泵浦功率持续增加,激光输出波长变为腔模波长激射,激光波长位于1002.4 nm。在单波长及双波长工作状态下VECSEL的光斑形貌均为高斯形貌的圆形对称激光光束,激光光束发散角半角由5.7°增加到7.9°。这种单芯片双波长输出VECSEL方案未来在抗干扰激光雷达以及频率转换太赫兹激光等方面有着很好的应用潜力。 相似文献
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垂直外腔面发射激光器(Vertical external cavity surface emitting laser,VECSEL)的侧向激射是制约其高性能工作的关键。我们设计了室温下量子阱增益峰与表面腔模大失配(30 nm)的增益芯片结构,并证实该结构可以有效抑制泵浦功率增加时VECSEL的侧向激射增强问题。增益芯片基底温度为20℃时,VECSEL正向激射波长位于980 nm,侧向激射波长位于950 nm,当泵浦功率逐步增加时,侧向激射强度随着正向激射的出现而迅速降低。这是因为激光正向激射时量子阱的受激辐射能级与正向激射激光模式匹配,正向激射的激光模式可以获取更高的模式增益,在与侧向模式的竞争中处于优势地位。当基底温度控制在0℃与10℃时,量子阱本征增益峰值与表面腔模失配度增大,此时VECSEL仍然表现出稳定的侧向激射抑制效果。 相似文献
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自由电子激光最初是一种量子理论,后来F.A.Hopf等证明可用经典理论加以描述。本文将从解Vlasov-Maxwell方程的不稳振荡出发来讨论自由电子激光,所得结果不仅可用于相对论电子来通过横向周期磁场产生激光,而且也适用于光波或微波与相对论电子束相互作用产生激光。比较了各种方案,对电子束单色性要求是高的,接着又讨论了电子回旋激射器的不稳振荡,求得波纹回旋激射器问题的解. 相似文献
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Harro G. Andresen 《Zeitschrift für Physik A Hadrons and Nuclei》1969,223(1):71-102
The conventional atomic beam preparation technique for hydrogen maser operation consists of a six pole magnetic field focussing in combination with adiabatically changing magnetic fields in the transition region between focusser and maser cavity, which results in a state selected, polarized ensemble of hydrogen atoms. Hydrogen maser operation with state selected, but unpolarized atoms has the advantage to reduce considerably the sensitivity of hydrogen maser frequency on coherently excited, low frequency,Δm F =±1 Zeeman transitions. The influence of the magnetic field pattern in the transition region on the energy level population probabilities for the focussed hydrogen beam has been analysed. Atomic beam preparation techniques using non-adiabatically changing magnetic field configurations in the transition region are described. The dependence of hydrogen maser oscillation on the energy level population within the atomic beam is theoretically investigated and the results are used for the analysis of the experimentally achieved atomic beam populations. It has been shown that a pulsed magnetic spin guidance field in the transition region, which switches between adiabatically changing magnetic field configurations and a sudden magnetic field reversal, results in an ensemble of hydrogen atoms with vanishing time averaged polarization, which does not deteriorate the conventionally achieved maser oscillation amplitude. 相似文献
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C. Mandache J. Nizet D. Leonard T. Bastin 《Applied physics. B, Lasers and optics》2012,107(3):675-677
In the construction and evaluation of the characteristics of a hydrogen maser, the oscillation parameter q remains an important parameter but somewhat difficult to determine precisely. Among the few techniques that exist to do such an evaluation we report on the technique using a variation of the quality factor of the microwave cavity. The results are compared to the standard theoretical model of operation of the maser accepted up to now. It is found that the technique described is extremely useful for determining the operational characteristics of such a maser. Furthermore, the experimental results and theoretical analysis are in reasonable agreement, which validates to a new level the hypothesis made in the development of the theory. 相似文献
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A magnetic field dependent phase shift between oscillation beat frequencies in a self-excited first and passive second cavity of a molecular beam Zeeman maser operated with two cavities in series is reported and interpreted. 相似文献
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S. N. Spark A. D. R. Phelps P. R. Winning 《International Journal of Infrared and Millimeter Waves》1991,12(8):885-894
The extended frequency tuning range of the Strathclyde University gyrotron is demonstrated. The gyrotron consisted of a field-immersed, field emission cold cathode and a shaped anode cavity. The cavity was oversized with an ill-defined boundary at one end. This system could therefore support the oscillation of a very large number of TEpqs modes. The maser was thus highly tunable via differential mode excitation. A heterodyne technique was used to demonstrate the maser oscillation in the Ka-band (26.5–40GHz), with the maser oscillating at 35GHz in the TE01 mode. Previous to this a quasi-optical diffraction grating spectrometer was used to show the maser was oscillating under different conditions respectively, single and multi-mode in the W-band (75–110GHz) and multi-mode in the G-band (140–220GHz). To control the output beam a quasi-optical mode converter has been successfully developed. This converts various TEpq modes into a Gaussian beam. Studying the output of the maser, the mm-wave pulse has been shown to consist of a 100ns envelope containing 2ns pulses spaced 5ns apart. Although this behaviour may have several explanations, some of the most recent code simulations predict this behaviour as a result of mode beating in the complex transient start-up of the maser oscillation. Since this gyrotron not only supports many transverse modes, but also several longitudinal modes, such beating is a likely consequence. 相似文献
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单原子脉塞和单原子激光是腔量子电动力学研究的重要实验平台。本文综述关于几类单原子脉塞和单原子激光的研究工作,包括德国Walther小组的单原子脉塞、超冷原子注入的单原子脉塞,法国Haroche小组的腔量子电动力学系统、注入原子的单原子激光、以及囚禁原子和囚禁离子的单原子激光。我们介绍相关的理论工作、实验系统、以及主要结果。 相似文献
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A two-wavelength oscillation C02 laser was constructed for the differential absorption measurement of low concentrations of atmospheric trace molecules and pollution molecules. A diffraction grating was alternately angle-modulated for the two-branch oscillation using a single C02 laser. The output power of the two wavelengths was balanced to be equal. With these characteristics, the phase-sensitive detection technique can be applied to give highly sensitive detection of the received power difference, which is proportional to the absorption in the optical path of the transmitted beams. A differential absorption spectrometer was used to demonstrate the usefulness of this two-wavelength laser oscillation method incorporating the output power balancing technique. The concentration of ethylene molecules was detected in a calibration cell and was also measured in real time in the exhaust of a combustion engine. From these results it has been shown that this differential absorption scheme offers a minimum detectable absorption of approximately 0.8%. 相似文献
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N. S. Ginzburg V. Yu. Zaslavsky I. V. Zotova A. M. Malkin N. Yu. Peskov A. S. Sergeev A. K. Kaminsky é. A. Perel’shtein S. N. Sedykh 《Radiophysics and Quantum Electronics》2009,52(8):557-563
We consider the possibility of implementation of a free-electron maser with a two-mirror resonator composed of modified and
conventional Bragg mirrors, operated in the short-wave part of the millimeter-wave range. The use of a modified Bragg mirror
based on the traveling and quasicritical wave coupling at the input of the interaction space permits the transverse-index
selection of modes. Amplification of the synchronous co-propagating wave by an electron beam is reached mainly in the regular
part of the resonator. Even slight reflections from the conventional output Bragg cavity, which directly couples the co- and
counter-propagating traveling waves, turn out to be sufficient for generation of self-excited oscillations. It is shown that
the new scheme of a free electron maser ensures the oscillation frequency stabilization with respect to the electron-energy
variation. With the optimal choice of the parameters, the oscillation frequency is close to the cutoff frequency of a quasi-critical
wave excited in the modified Bragg structure. 相似文献