共查询到20条相似文献,搜索用时 15 毫秒
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Berden G Jamison SP MacLeod AM Gillespie WA Redlich B van der Meer AF 《Physical review letters》2004,93(11):114802
Electro-optic detection of the Coulomb field of a relativistic electron bunch combined with single-shot cross correlation of optical pulses is used to enable single-shot measurements of the shape and length of femtosecond electron bunches. This method overcomes a fundamental time-resolution limit of previous single-shot electro-optic measurements, which arises from the inseparability of time and frequency properties of the probing optical pulse. Using this new technique we have made real-time measurements of a 50 MeV electron bunch, observing the profile of 650 fs FWHM ( approximately 275 fs rms) long bunches. 相似文献
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We have realized a novel Mach-Zehnder interferometer (MZI) thermo-optic switch that can operate over a much wider wavelength range than a conventional MZI switch. We constructed the novel MZI switch by incorporating a phase-generating coupler (PGC) as an optical coupler. The PGC generates a nonlinear wavelength-dependent phase, which functions as a virtual wavelength-dependent delay part that cancels out the wavelength dependence of a MZI. We fabricated the novel MZI switch on a silica-based planar light-wave circuit and achieved a low insertion loss of less than 1.6 dB and a high extinction ratio of 30 dB over a wide wavelength range of 160 nm. 相似文献
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S. A. Aseev B. N. Mironov V. G. Minogin S. V. Chekalin 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(7):931-933
A combination of femtosecond laser techniques and nanomicroscopy creates promising new possibilities for studying both matter
and a whole number of ultrafast physical processes. The results obtained at the Institute for Spectroscopy as a result of
developing a new area of femtosecond nanomicroscopy are presented. 相似文献
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Improvement of femtosecond SPPs imaging by two-color laser photoemission electron microscopy 下载免费PDF全文
Chun-Lai Fu 《中国物理 B》2022,31(10):107103-107103
Clear imaging of surface plasmon polaritons (SPPs) is a prerequisite for SPPs-based applications. In this work, we demonstrate an improvement of near-field imaging of SPPs via directly comparing the visibility of the photoemission electron microscopy (PEEM) image of SPPs under one- and two-color laser excitation (also known as one- or two-color laser PEEM). By measuring the photoelectron yield and the contrast of the interference fringes of SPPs, we demonstrate that in addition to enhancing the photoemission yield, two-color laser PEEM can significantly improve the contrast between bright and dark fringes (nearly 4 times higher than that of one-color laser case). By recording the nonlinear order of the photoelectrons ejected from the bright and dark fringes, respectively, the underlying mechanism for the improved visibility is revealed. In addition, the influences of the polarization direction of 400-nm laser on the PEEM images of the SPPs with different wave vector directions are shown. These results can provide technical support for the development of SPPs-based communication devices and catalysis. 相似文献
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The main characteristic of this interferometric system is such that the systems can be used for DCN laser (=195m, 190m) and also for HCN laser (=337m) by changing the work medium, regulating the temperature of tube wall and adjusting the optic path, without changing any optic element. 相似文献
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D. Véron 《Optics Communications》1974,10(1):95-98
This paper describes a high sensitivity 337 μm HCN laser interferometer for plasma electron density measurements. The plasma phase shift is transferred to a low frequency signal obtained by slightly shifting the frequency of the 337 μm radiation in the reference beam of the interferometer. The frequency shift is produced by diffracting the radiation of a cylindrical rotating blazed grating. A phase shift is deduced from the time variation of the zero crossings of the low frequency signal, giving a result which is independent of amplitude fluctuations. Using pyroelectric detectors, the interferometer has a time resolution of 100 μsec and a sensitivity of 10-2 fringe. 相似文献
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S. Nemoto 《Optical and Quantum Electronics》1984,16(2):165-171
This paper presents an accurate method for observing fringe movement in a Mach-Zehnder type fibre interferometer. We place a photodetector in each of two interference patterns formed by a half-mirror and waves emitted from single-mode fibres. By applying the output voltages of the detectors to X- and Y-terminals of an oscilloscope, we can observe the fringe movement as a rotation of a bright spot along a Lissajous figure. 相似文献
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Electron density measurements are periormed on HT-6M tokamak using a 7 channel Far-Infrared HCN laser interferometer. From the measured line integrals--7 channel phase shifts the electron density profile is reconstructed by a fit procedure. Results were tested by comparison to Abel inverted. Some recent interesting experimental results were reported. 相似文献
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We present a fiber interferometer for the simultaneous measurement of phase at multiple wavelengths from a single broadband femtosecond laser. Narrow-bandwidth fiber Bragg gratings isolate a particular frequency from the broad-bandwidth laser pulse produced. The multiwavelength phase data permit the unambiguous measurement range to be significantly increased compared with the wavelengths used in the interferometer. Preliminary experimental results are presented for a two-frequency sensor with an absolute range of 0.13 mm and associated dynamic range of 43,000:1. 相似文献
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We show that the momentum flexibility of inelastic x-ray scattering may be exploited to invert its loss function, allowing real time imaging of density disturbances in a medium. We show the disturbance arising from a point source in liquid water, with a resolution of 41.3 attoseconds (4.13 x 10(-17) s) and 1.27 A (1.27 x 10(-8) cm). This result is used to determine the structure of the electron cloud around a photoexcited chromophore in solution, as well as the wake generated in water by a 9 MeV gold ion. We draw an analogy with pump-probe techniques and suggest that energy-loss scattering may be applied more generally to the study of attosecond phenomena. 相似文献
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We report a miniaturized inline Fabry-Perot interferometer directly fabricated on a single-mode optical fiber with a femtosecond laser. The device had a loss of 16 dB and an interference visibility exceeding 14 dB. The device was tested and survived in high temperatures up to 1100 degrees C. With an accessible cavity and all-glass structure, the new device is attractive for sensing applications in high-temperature harsh environments. 相似文献
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在星光Ⅱ铷玻璃激光装置上,采用两级喇曼压缩系统产生的波长为308 nm的紫外光作为探针束,配合Nomarski偏振干涉仪对金平面靶冕区激光等离子体进行诊断。308 nm光具有波长短、亮度高、脉冲时间短、相干性好的优点,作为探针束诊断冕区产生的等离子体电子密度,可以与高功率激光装置打靶激光同步,实现有效地脉冲压缩,同时避免等离子体中谐波分量的干扰。实验获得了308 nm紫外探针光偏振干涉条纹图,在研究Abel反演算法的基础上,利用自行研制的基于Windows操作系统的实验数据处理软件,对实验数据进行了处理和分析,得到了冕区等离子体电子密度的空间分布。结果表明:两级喇曼压缩系统配偏振干涉能有效抑制主束谐波影响,以更高时间分辨测量等离子体的更高密度区域。 相似文献
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在星光Ⅱ铷玻璃激光装置上,采用两级喇曼压缩系统产生的波长为308 nm的紫外光作为探针束,配合Nomarski偏振干涉仪对金平面靶冕区激光等离子体进行诊断。308 nm光具有波长短、亮度高、脉冲时间短、相干性好的优点,作为探针束诊断冕区产生的等离子体电子密度,可以与高功率激光装置打靶激光同步,实现有效地脉冲压缩,同时避免等离子体中谐波分量的干扰。实验获得了308 nm紫外探针光偏振干涉条纹图,在研究Abel反演算法的基础上,利用自行研制的基于Windows操作系统的实验数据处理软件,对实验数据进行了处理和分析,得到了冕区等离子体电子密度的空间分布。结果表明:两级喇曼压缩系统配偏振干涉能有效抑制主束谐波影响,以更高时间分辨测量等离子体的更高密度区域。 相似文献
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We present a simple method to measure the refractive index dispersion over a broad wavelength range (0.6-1.6 μm). In a first step, the optical group indices are obtained by measuring the time-retardation of tunable 150 fs laser pulses within a sample relative to air. The refractive index dispersion is then calculated using a Sellmeier equation that describes the measured group index dispersion. We show that our experimental data agree with previously published results to within 2 × 10−4 for a 3 mm thick sample of fused silica and to within 3 × 10−3 for the index n1 of a 2 mm thick crystal of the highly dispersive and anisotropic organic crystal 4-N,N-dimethylamino-4′-N′-methyl stilbazolium tosylate (DAST). 相似文献