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111.
Broadly Tunable SOA-Based Active Mode-Locked Fibre Ring aser by Forward Injection Optical Pulse
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We present a broadly tunable active mode-locked fibre ring laser based on a semiconductor optical amplifier (SOA), with forward injection optical pulses. The laser can generate pulse sequence with pulsewidth about 12ps and high output power up to 8.56 dBm at 2.5 GHz stably. Incorporated with a wavelength-tunable optical bandpass filter, the pulse laser can operate with a broad wavelength tunable span up to 37nm with almost constant pulsewidth. A detailed experimental analysis is also carried out to investigate the relationship between the power of the internal cavity and the pulsewidth of the output pulse sequence. The experimental configuration of the pulse laser is very simple and easy to setup with no polarization-sensitive components. 相似文献
112.
Modulation of Splitting Beam Angle with Metal--Nonlinear Optical Material--Metal (M-NL-M) Array Structure 总被引:1,自引:0,他引:1
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WANG Xiao-Lei WANG Pei MIN Chang-Jun CHEN Jun-Xue LU Yong-Hua MING Hai 《中国物理快报》2008,25(12):4375-4377
We demonstrate active manipulating plasmonic signals with metal--nonlinear optical material--metal (M-NL-M) arrays consisting of slits with variant widths. The parameters of the M-NL-M array structure are derived by theoretical analysis of dispersion relationship. The splitting angle can be modulated by the incident light intensity, and verified by a nonlinear two-dimensional finite difference time domain method. The physical principle of this phenomenon is analysed from the phase of surface plasmon polaritons and Fabry--Pérot (F-P) resonance in slits 相似文献
113.
H. Huhtinen R. Laiho L.S. Vlasenko M.P. Vlasenko V. Zakhvalinskii J. Leiro S. Mattila F. Sutara M. Vondracek 《Journal of magnetism and magnetic materials》2008
Light-induced changes of the hysteresis loops of magnetization and microwave absorption are investigated in low-doped La1−xCaxMnO3 (x<0.2) thin films. The width of the hysteresis loops decreases clearly under illumination with visible or near-infrared light at temperatures below 50 K. The microwave conductivity has a minimum value at magnetic fields corresponding to the magnetization reversal and is shifted towards weaker fields under illumination. These effects show complex nonexponential time evolution and dependence on strength of the magnetic field. The results can be explained by assuming that small ferromagnetic metallic regions exist within the insulating ferromagnetic phase of the sample, and that these regions are expanded by optically induced charge transfer between Jahn–Teller split eg states of neighboring Mn3+ ions. Decrease of the Mn3+ XPS core level spectrum is observed in the samples under illumination with a HeNe laser. 相似文献
114.
A new harmonic detection scheme for fully digital, fast-scanning wavelength-modulation spectroscopy (DFS-WMS) is presented. DFS-WMS is specially suited for in situ absorption measurements in combustion environments under fast fluctuating transmission conditions and is demonstrated for
the first time by open-path monitoring of ambient oxygen using a distributed-feedback diode laser, which is doubly modulated
with a fast linear 1 kHz-scan and a sinusoidal 300 kHz-modulation. After an analog high-pass filter, the detector signal is
digitized with a 5 megasample/s 12-bit AD-converter card plugged into a PC and subsequently – unlike standard lock-ins – filtered
further by co-adding 100 scans, to generate a narrowband comb filter. All further filtering and the demodulation are performed
completely digitally on a PC with the help of discrete Fourier transforms (DFT). Both 1f- and 2f-signals, are simultaneously
extracted from the detector signal using one ADC input channel. For the 2f-signal, a linearity of 2% and a minimum detectable
absorption of 10-4 could be verified experimentally, with the sensitivity to date being limited only by insufficient gain on the 2f-frequency
channel. Using the offset in the 1f signal as a transmission ‘probe’, we could show that the 2f-signal can be transmission-corrected
by a simple division by the 1f-background, proving that DFS-WMS provides the possibility of compensating for transmission
fluctuations. With the inherent suppression of additive noise, DFS-WMS seems well suited for quantitative in situ absorption spectroscopy in large combustion systems. This assumption is supported by the first measurements of oxygen in
a high-pressure combustor at 12 bar.
Received: 29 April 2002 / Revised version: 31 May 2002 / Published online: 12 September 2002
RID="*"
ID="*"Corresponding author. Fax: +49-6221/545-050, E-mail:volker.ebert@pci.uni-heidelberg.de 相似文献
115.
116.
U. M. Heller 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):769-772
The MILC Collaboration has been performing realistic simulations of full QCD with 2 + 1 flavors of improved staggered quarks.
Our simulations allow for controlled continuum and chiral extrapolations. I present results for the light pseudoscalar sector:
masses and decay constants, quark masses and Gasser-Leutwyler low-energy constants. In addition I will present some results
for heavy-light mesons, decay constants and semileptonic form factors, obtained in collaboration with the HPQCD and Fermilab
lattice Collaborations. Such calculations will help in the extraction of CKM matrix elements from experimental measurements. 相似文献
117.
Cyril Drag 《Optics Communications》2007,275(1):190-195
A two-colour laser technique is developed for photodetachment microscopy, by means of microwave modulation of a CW single-mode dye laser. A phase modulation regime is achieved through an electro-optical LiNbO3 crystal excited at the frequency 1.95 GHz. The two first sidebands created are selected by rejection of the other orders through a plane Fabry-Perot interferometer. With the resulting two-colour radiation, the photodetachment microscopy technique is applied to a beam of 32S− ions. It is shown that the superposition of the two resulting interference patterns can be used as a ‘spectral vernier’ to remove the uncertainty on the electric field and absolute energy scale. Without any initial assumption on the value F of the electric field in the laser-ion interaction region, a measure of F and of the electron affinity eA of Sulfur can be obtained. Putting 16 recordings of two-colour photodetachment interferograms together, with the only condition that F be the same for all experiments, one gets eA(32S) = 16752.978(11) cm−1, which is quite compatible, even though not as accurate, with the most recently recommended value eA(32S) = 16752.9760(42) cm−1. A proposal is made for going from an incoherent to a coherent two-colour photodetachment scheme, which would make photodetachment interferograms sensitive to a new degree of freedom. 相似文献
118.
We show numerically that when a soliton circulating in the laser cavity experiences dynamical bifurcations, extra sets of sidebands appear in the soliton spectrum. The new sidebands have clearly different characteristics to those of the conventional soliton sidebands, indicating that there exists a new mechanism of sideband generation in the lasers. 相似文献
119.
A Laser-Diode-Pumped Widely Tunable Single-Longitude-Mode Tm:YAP Laser at Room Temperature 总被引:1,自引:0,他引:1
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A laser-diode-pumped widely tunable single-longitude-mode TIn:YAP laser in 2μm eye-safe region is built. Con- tinuous tanable range from 1899nm to 2025nm is achieved with the maximum laser output power of 225mW at 1989 am. In addition, the TIn:YAP laser operating under multimode and slngle-mode conditions is discussed. 相似文献
120.
KITAZAWA Tazuko MIYANISHI Shintaro MURAKAMI Yoshiteru KOJIMA Kunio TAKAHASHI Akira 《中国物理快报》2007,24(10):2827-2829
We observe surface plasmon polariton (SPP) refraction on a metal heterostructured sample with a scattered-type scanning near-field optical microscope (SNOM). The sample consists of AI and Au in-plane whose boundary is smooth enough with proper etching time. SPPs excited on the AI film travel to the boundary and a portion of SPPs propagates into the Au film. In addition, interference fringes appear in the SNOM image bent at the boundary. The result is analysed with effective index method and the refracted angle is explained by Shell's law. 相似文献