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1.
Observation of Mode Patterns for High Purity Mode Operation in the Submillimeter Wave Gyrotron FU VA
T. Idehara I. Ogawa S. Maeda R. Pavlichenko S. Mitsudo D. Wagner M. Thumm 《International Journal of Infrared and Millimeter Waves》2002,23(9):1287-1295
Operation tests of a cavity designed for high purity mode operation of the submillimeter wave gyrotron FU VA has been carried out successfully. The observed emission patterns of several cavity modes appear very pure and are compared with calculated results. High purity mode operation has the advantage of making the conversion to Gaussian-like beams more efficient. 相似文献
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We design a single-ridged coaxial hybrid coupler which excites a TE011 mode of high mode content in a cylindrical cavity, resonating at 28.2GHz. The coupler consists of a WR-28 rectangular waveguide, a coaxial TEn11 cavity, and a cylindrical TE011 cavity. Both TE311 coaxial cavity and TE411 single-ridged coaxial cavity are analyzed to examine the TE011 mode purity in the central cavity. Mode purity analysis is performed by a field expansion method using Fourier-Bessel orthonormal basis functions. Numerical calculations predict that the TE411 single-ridged coaxial cavity excites the TE011 mode with mode purity of 98.6%, which is improved by 3% higher compared with the TE311 coaxial cavity. Measurements on the single-ridged coaxial coupler show a resonant frequency at 28.078GHz and ohmic and external Qs of 1560, 473 respectively, which are in good agreement with the simulated results of a 3-D finite element electromagnetic code. 相似文献
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N. R. Heckenberg B. J. Renton S. T. Shanahan W. Wright 《Applied physics. B, Lasers and optics》1982,29(2):67-72
The effect of injecting radiation from a cw waveguide CO2 laser into a TEA laser through a hole in one mirror of its unstable resonator has been studied experimentally. High-power single longitudinal mode operation of the TEA laser is achieved over a wide but finite range of injection frequencies, the frequency of the single-mode pulse being that of the TEA laser cavity mode lying closest to the injected frequency. Although a simple theoretical model shows good qualitative agreement with observations it underestimates the range of injection frequencies which result in single-mode pulses unless a fast chirping of the cavity mode frequency is postulated. 相似文献
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We have designed and realized a compact external cavity semiconductor laser operating around 850 nm. The main characteristics are the following: a 32 nm tuning range, a stable single mode operation always attainable in this range and a linewidth of a few hundred kilohertz. This spectral purity improvement is the result of an increased photon lifetime in the external cavity. The potentiality of this solid state laser source is finally underlined. 相似文献
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复合腔全光纤环形激光器单纵模双向同时激射的实验研究 总被引:5,自引:0,他引:5
提出并实验证实了三能级掺杂光纤复合腔环形激光器共振选模振荡原理和腔内自建可饱和吸收机制对双向行波共振谱的去耦作用,并实现复合腔掺Er^3+全光纤环形激光器单纵蓦以向同时激射。 相似文献
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The single longitudinal mode (SLM) characteristics of narrow linewidth long-external-cavity semiconductor lasers has been improved significantly by using a multisegment composite-cavity configuration. In this paper, the mode selectivities of two-segment, three-segment and four-segment cavity semiconductor lasers have been analysed and compared. In experiments, a four-segment composite cavity laser exhibits SLM oscillation with side-mode suppression ratio of 30 dB even for total external cavity length of 75 cm. The oscillation linewidth is less than 200 kHz. 相似文献
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针对Danilov (2007) 提出的高阶模式激励器纯度未知和设计思路模糊的不足, 介绍了一种改进型螺旋分布孔高阶旋转模式激励器, 以实现同轴TE1, 1模式到圆波导TE5, 3模式的高纯度转换。根据不均匀弦方程, 编制了数值计算程序对同轴腔体结构参数进行了优化计算, 使工作模式能够有效谐振。基于小孔衍射理论以及PEC表面的电场边界条件, 详细研究了螺旋分布孔的排列方式和模式抑制器的工作原理。数值计算和仿真结果表明: 在中心频率30GHz附近, TE5, 3模式激励器的模式纯度高达97.4%, 转换效率为96.1%。设计的高阶模式激励器相对于Danilov的结构具有纯度高和紧凑的性能。 相似文献
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We propose a scheme for generation of SU(2) coherent states for an atomic ensemble and a cavity mode. In the scheme a collection of two-level atoms resonantly interact with a single-mode quantized field. Under certain conditions, the system can evolve from a Fock state to a highly entangled SU(2) coherent state. The operation speed increases as the number of atoms increases, which is important in view of deeoherence. 相似文献
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X. Yang O. Drumm A. Arnold E. Borie G. Dammertz K. Koppenburg B. Piosczyk D. Wagner M. Thumm 《International Journal of Infrared and Millimeter Waves》2003,24(10):1599-1608
The quasi-optical mode converter for a frequency step-tunable gyrotron which consists of a dimpled-wall antenna (Denisov-type launcher) and a beam-forming mirror system has been optimized for 9 modes from TE17,6 at 105 GHz to TE23,8 at 143 GHz. The first mirror is a large quasi-elliptical focusing one; the second and third are phase-correcting mirrors with a non-quadratic shape of the surface. The results of calculations show that for these modes the Denisov-type launcher has a well-focused beam with low diffraction losses, and the radiation pattern presents an almost identical field shape for all modes considered. A multi-mode optimization of the phase-correcting mirrors with two different methods has been tested. The simulations show that the phase-correcting mirrors can be used for broadband operation in the frequency range from 105 GHz up to 143 GHz in the various design modes. This quasi-optical mode converter can achieve efficiencies of 94%-98% for converting the rotating high-order cylindrical cavity modes into the usable fundamental Gaussian mode. 相似文献
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X. Yang A. Arnold E. Borie G. Dammertz O. Drumm K. Koppenburg B. Piosczyk D. Wagner M. Thumm 《International Journal of Infrared and Millimeter Waves》2004,25(11):1557-1566
A broadband quasi-optical (QO) mode converter for a multi-frequency gyrotron has been designed and tested at Forschungszentrum Karlsruhe (FZK). The launcher is optimized for the TE22,8 mode at 140 GHz, but the radiated beams present an almost identically focused pattern for all 9 considered modes between 105 GHz (TE17,6) and 143 GHz (TE23,8). Combining with a beam-forming mirror system, which consists of a quasi-elliptical mirror and two phase-correcting mirrors with non-quadratic surface contour, further calculations show that efficiencies of more than 94% have been achieved for converting the rotating high-order cylindrical cavity modes into the usable fundamental Gaussian mode. Low power (cold) measurements show a good agreement with theoretical predictions. This QO mode converter can be used for the broadband operation of a multi-frequency 1 MW gyrotron. 相似文献
14.
Mode Suppression Phenomenon in a Mode Splitting He-Ne Laser 总被引:1,自引:0,他引:1
The mode competition is significant in laser physics and applications. A priority frequency will suppress, in competition, a potential frequency within gain profile, and this becomes more obvious with greatly decreasing the spacing of the two frequencies. The small spacing is produced by splitting one mode into two orthogonally polarized frequencies in a 0. 6328 μm He-Ne laser with a short cavity length (150 mm long). By tuning the cavity length, the intensities of the two frequencies (e-mode and o-mode) under a ariety of frequency spacings is measured. The suppression bandwidth for the potential mode is up to several hundreds of MHz and changes with the frequency spacing of the pair of frequencies. The intensities for the two frequencies are vary oppositely. 相似文献
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T. Idehara N. Nishida K. Yoshida I. Ogawa T. Tatsukawa D. Wagner G. Gantenbein W. Kasparek M. Thumm 《International Journal of Infrared and Millimeter Waves》1998,19(7):919-930
The cavity of the newest gyrotron, Gyrotron FU IVA in the high frequency series of Fukui University gyrotrons (the Gyrotron FU series) is designed to minimize the mode conversion from the main cavity mode to the higher modes. In this paper, the experimental results are compared with simulations for the complete gyrotron oscillator. The gyrotron has an additional advantage to cover the wide frequency range in submillimeter wave region. 相似文献
16.
The mode competition is significant in laser physics and applications. A priority frequency will suppress, in competition, a potential frequency within gain profile, and this becomes more obvious with greatly decreasing the spacing of the two frequencies. The small spacing is produced by splitting one mode into two orthogonally polarized frequencies in a 0. 6328 μm He-Ne laser with a short cavity length (150 mm long). By tuning the cavity length, the intensities of the two frequencies (e-mode and o-mode) under a ariety of frequency spacings is measured. The suppression bandwidth for the potential mode is up to several hundreds of MHz and changes with the frequency spacing of the pair of frequencies. The intensities for the two frequencies are vary oppositely. 相似文献
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Generally, dipole mode is a doubly degenerate mode. Theoretical calculations have indicated that the single dipole mode of two-dimensional photonic crystal single point defect cavity shows high polarization property. We present a structure with elongated lattice, which only supports a single y-dipole mode. With this structure we can eliminate the degeneracy, control the lasing action of the cavity and demonstrate the high polarization property of the single dipole mode. In our experiment, the polarization extinction ratio of the y-dipole mode is as high as 51:1. 相似文献
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对Ka波段工作模式为TE01模和TE02模的两种回旋速调管的输入耦合器进行了详细研究,利用模式匹配理论和HFSS建模仿真计算了内圆柱腔和外同轴腔的尺寸;提出了一种与软件计算相结合的模式纯度计算方法,对内腔工作模式纯度、内外腔能量分数进行了计算。内腔侧面上的耦合缝的大小、角向位置都直接决定外同轴腔内的TEm11模向内圆柱腔的TE0n1模的耦合情况。针对耦合缝与输入波导成45°和0°分布两种情况,研究了耦合缝长、宽和角向偏移,以及内外腔频差对频率、Q值及内腔能量分数的影响。分别设计了Ka波段内腔工作模式为TE011、外腔为TE411和内腔TE021、外腔TE811的两种输入耦合器,并利用矢量网络分析仪对内腔工作模式为TE011的耦合器进行了冷高频测量,测得频率为34.257 GHz,与计算结果34.300 GHz仅相差43 MHz。 相似文献
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The frequency stability of He-Ne-Lasers was investigated by heterodyning two free running laser oscillators. Measurements were performed in a laser device of high mechanical stability protected against acoustical noise. For single mode operation the stability and spectral purity of the laserfrequency was found to be well defined by the constancy and bandwidth of the beat frequencies. In multimode operation beat frequencies were found which were nearly independent from the oscillator cavity length. They were produced by inevitable nonlinearities in the electronic equipment. For pointing out this effect more clearly, an additional nonlinear element was introduced into the electronic circuit. The additional nonlinearity was found to produce the same beatfrequencies as observed before, but with higher amplitudes. Presence of these second order beats may lead to misinterpretation of the frequency stability. From the minimum obtained beat frequency of 200 c/s in single mode operation it was concluded that a minimum laser bandwidth of smaller than 200 c/s was realized. 相似文献