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81.
Ultrafast Third-Order Nonlinear Optical Response of Organic-Inorganic Hybrid Materials (C19H25N2)7Hn [P2Mo18-n Vn O62] 下载免费PDF全文
We have measured the third-order optical nonlinearity of the organic-inorganic hybrid materials of supermolecules (C19H25N2)7Hn [P2Mo18-n Vn O62] (n = 1, 2, 4, 5) and their reactants (C19H25N2) Br and Hn 6[P2Mo18-n Vn O62] by using the ultrafast optical Kerr effect at 830 nm wavelength, with time resolution of 115fs. By comparing the γ values of the supermolecules and their reactants, it is concluded that the charge-transfer eahanced remarkably the third-order optical nonlinearity of the compounds. With the increment of the number of the vanadium atoms,the electron distribution changed strongly and the γ value decreased dramatically. 相似文献
82.
Measuring Carrier-Envelope Phase of Few-Cycle Laser Pulses Using High-Order Above-Threshold Ionization Photoelectrons 下载免费PDF全文
We experimentally demonstrate the measurement of carrier-envelope phase of few-cycle laser pulses. We have built a stereo above-threshold ionization setup. The photoelectron energy spectra of high-order above-threshold ionization are measured in both the left and right directions in the linearly polarized laser fields. It is shown that the left-right asymmetry of the spectra is dependent on carrier-envelope phase of few-cycle laser pulses. Two asymmetry parameters from the low-energy and high-energy regions at the above-threshold ionization plateau map a phase ellipse, in which the points indicate the absolute value of carrier-envelope phase. We have calibrated the phase ellipse by comparison with the semiclassical calculation. This setup allows us to determine the value of the absolute phase of few-cycle laser pulses. 相似文献
83.
84.
降低阈值是随机激光实用化的前提, 随机光纤激光器是将随机增益介质填充到空芯光子晶体光纤中利 用其光子禁带来降低阈值的一种随机激光器. 理论分析表明: 在光子晶体光纤光子禁带的约束下, 随机光纤激光器中的大部分能量被集中在芯区传播, 这使局域在芯区的光与随机介质相互作用得到增强, 激发效率得以提高. 然而, 光纤填充介质后, 纤芯等效折射率发生了改变, 光子带隙也会随之移动, 因此当选用带隙光纤来降低阈值时, 只考虑光纤本身的带隙是不够的, 应考虑到介质的增益频率和填充后的光子带隙之间的匹配问题, 合理选择光纤或介质的材料, 如果匹配得当, 光子禁带对激光的调控能力会更强, 激光阈值有望得到更大程度的降低.
关键词:
随机激光
光子晶体光纤
光子禁带
阈值 相似文献
85.
Enhancing light–matter interaction in cavity quantum electrodynamics has aroused widespread interests in on-chip quantum information processing. Here, we propose a hybrid nanotoroid–nanowire system to enhance photon–exciton interaction. A nanoscale gap is formed by placing a dielectric nanowire close to a dielectric nanotoroid, where the coupling coefficient between photon and emitter can achieve 5.55 times of that without nanogap. Meanwhile, the cavity loss and spontaneous emission of the emitter will remain at a small value to guarantee the realization of strong coupling. The method might hold promise for the research of nanophotonics,quantum optics, and novel optical devices. 相似文献
86.
We present an experimental investigation of a
filamentation-assisted fourth-order nonlinear optical process in KTP
crystals pumped by intense 1.53~eV (807~nm) femtosecond laser
pulses. Femtosecond light pulses at 2.58~eV (480~nm) are generated
by the fourth-order nonlinear polarization (P4(ω 2 ) =
χ 4(ω 2 ,ω ,ω ,ω ,- ω 1
)E3(ω )E* (ω 1 ), where E(ω ) corresponds to
the pump frequency and E(ω 1 ) to the supercontinuum
generated through filamentation). If the system is seeded by a laser
beam at ω 1 or ω 2 and there are spatial and
temporal overlaps with the pump beam, E(ω 1 ) and E(ω
2 ) are simultaneously amplified. When the intensity of the seed
laser beam exceeds a certain intensity threshold, the contribution
of P4(ω ) = χ 4(ω ,ω 1 ,ω 2 ,-ω, - ω )E(ω 1 )E(ω 2 )(E* (ω))2 becomes non-negligible, and the amplification weakens. The
conversion efficiency from the pump to the signal at 2.58~eV
(480~nm) attains to 0.1%. 相似文献
87.
We use two parallel nano-slits in a silver film to form a surface plasmon Mach Zehnder interferometer (MZI), based on the interference of two surface plasmon waves propagating along the two surfaces of the silver film. Coating the silver film with a photoinduced birefringence polymer film, we achieve optical modulation of the MZI output by changing the refractive index of the polymer film with a pump beam. An on/off ratio 0f 2. 7 is obtained for a probe wavelength of 865 nm. 相似文献
88.
Static and transient spectroscopic characters of newly synthesized start-like molecules, 1,3,5-tri(10-butyl-3-propenyl-10H-phenothiazine)-benzene (TP3B) and 2,4,6-tri(10-butyl-3-propenyl -10H-phenothiazine)-[1,3,5]triazine (TP3T), are studied using static, picosecond fluorescence and femtosecond transient absorption spectroscopy. The results show that when the benzene group is in the center, a large conjugation system is formed, while a fast electron-transfer process happens when the center group is triazine. 相似文献
89.
We propose a triple encrypted holographic memory containing a digital holographic system. The original image is encrypted using double random phase encryption and stored in a LiNbO3:Fe crystal with shift-multiplexing. Both the reference beams of the memory and the digital holographic system are random phase encoded. We theoretically and experimentally demonstrate the encryption and decryption of multiple images and the results show high quality and good fault tolerance. The total key length of this system is larger than 4.7×10^33. 相似文献
90.
SOLVATION DYNAMICS OF METHANOL INVESTIGATED BY FEMTOSECOND TIME-RESOLVED FLUORESCENCE UP-CONVERSION TECHNIQUE 下载免费PDF全文
The solvation dynamics of methanol has been investigated using a femtosecond time-resolved fluorescence up-conversion technique. Transient fluorescence spectra of Coumarin 152A dissolved in methanol at different time were reconstructed from the measured fluorescence decays. The Stokes shift was obtained and the solvent response function Sv(t) was fitted using a bimodal function with a fast Gaussian component and a slow bi-exponential component. The Gaussian component was attributed to the effect of free streaming motion of the solvent molecules, whereas the bi-exponential component was caused by the rotational diffusion motion of the solvent molecules. A comparison of our results with reported data was made. 相似文献