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The stationarity region, i.e., the area in which the statistics of a propagation channel remain constant, is an important measure of the propagation channel, and essential for efficient system design. This paper presents what is to our knowledge the first extensive measurement campaign for measuring the stationarity region of MIMO mm-wave channels. Using a novel 28 GHz phased-array sounder with high...
Numerical and experimental demonstrations are presented to reduce the distortion induced by intense terahertz field in a cross-polarized terahertz time-domain spectroscopy system. A quarter-wave plate is used to increase the initial birefringence of the probe beam. With an optimized angle, the distortion can be removed effectively, while the signal-to-noise ratio of the system is also improved.
Metal film materials have been widely used in optical devices, green energy field, biosensor technologies, and so on. In these applications, the properties of metal surface play the significant role. However, propagation characteristics of light in metal-based materials are still confusing. Wavelength-dependent refraction going from negative to positive at air/metal interface was reported in previous...
The European XFEL is an extremely brilliant Free Electron Laser Source with a very demanding pulse structure: trains of 2700 X-Ray pulses are repeated at 10 Hz. The pulses inside the train are spaced by 220 ns and each one contains up to 1012 photons of 12.4 keV, while being ≤ 100 fs in length. AGIPD (Adaptive Gain Integrating Pixel Detector) is a hybrid 1M-pixel detector developed by DESY, PSI, and...
913 nm tapered diode lasers with 23th order laterally coupled grating is fabricated. Power of over 560 mW/facet and lateral divergence angle of 2.1° are achieved. Measured side mode suppression ratio is about 27 dB.
Stimulated Raman scattering (SRS) is one of most efficient methods for generating new laser lines. In recent years, SRS in crystalline Raman media have attracted much attention for the advantages of high Raman scattering gain, favorable thermal conductivity and good mechanical and chemical stability [1-3]. So far most crystalline Raman lasers focus on Stokes generation. In contrast to Stokes generation,...
With recent developments in Heat Assisted Magnetic Recording (HAMR), there is growing intense interest in the thermal-optical properties of the HAMR media. We detect the phase change of the optical beam as it reflects from a FePt thin film under strong thermal gradient by carrying out Close-Aperture reflection Z-scan experiments. It was found that the far field spatial distribution of the reflected...
We experimentally demonstrate a new coherent absorption phenomenon, through which a planar photonic metamaterial may resonantly absorb 100% of incident light. The effect is a time-reversed analogue ‘Lasing Spaser’ action.
We have demonstrated an intense plasma-based THz source using ~5 TW femtosecond laser pulses to irradiate solid targets. The energy of a single THz pulse emitted in the laser specular direction increases with the laser energy. The maximum THz energy can be as high as tens μJ/sr. The polarization of the THz pulse is measured to be linear.
We have demonstrated an intense plasma-based THz source using ~5 TW femtosecond laser pulses to irradiate solid targets. The energy of a single THz pulse emitted in the laser specular direction increases with the laser energy. The maximum THz energy can be as high as tens μJ/sr. The polarization of the THz pulse is measured to be linear.
Experiments of photoionized plasmas and shock wave generation, which are related to laboratory astrophysics, have been performed with the Shengguang II laser facility. Some preliminary results are presented in this paper.
We report high precision refractive indices measurement of air and its constitute gases using an unbalanced Mach-Zehnder interferometer with frequency combs. Our experiments demonstrate sensitivities in levels of 10-9.
E-SPART analyzer is an instrument capable of measuring aerodynamic diameter and electrostatic charge distributions on a single particle basis in real time. A frequency biased laser Doppler velocimeter (LDV) is used to make non- contact in-situ analysis of the particles under ambient conditions, with respect to the temperature, pressure, and composition of the gaseous medium in which the particles...
We report improved high precision refractive index measurement of air and CO2 using a Michelson interferometer setup with frequency combs as the light source. Our experiment has a sensitivity of 9.6 x 10-9.
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