共查询到20条相似文献,搜索用时 28 毫秒
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研究了由一维光子晶体构成的Bragg微腔(AB)^N(D)^2(BA)^N中三阶非线性光学介质(NLM)产生的相位共轭波的增强效应。当入射光波与Bragg腔模满足共振条件时,推导了其相位共轭波的增强因子。Bragg微腔中的三阶NLM产生的相位共轭波相对于该介质裸露时产生的相位共轭波具有明显增强,这主要是Bragg微腔对入射泵浦光产生了较大的共轭增强作用。理论分析和数值计算结果还表明,当入射光波与Bragg腔模满足共振条件且周期数N较大时,该结构可等效于由Bragg反射镜组成的Fabry-Perot(F-P)腔。 相似文献
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Based on the nonlinear medium transfer theory, optical bistability of nonlinear microcavity is investigated at oblique incidence. It is found that the critical frequency of incident light inducing bistability phenomenon is related to the polarization and incident angle. The critical frequency increases with the incident angle. Increasing the incident angle can make bistability happen easier for focusing Kerr medium, but will hinder bistability for defocusing Kerr medium. The bistability switch threshold of TE mode is significantly lower than that of TM mode at a large incident angle. 相似文献
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报导对一组[Ru(bpy)2L]2+络合物的光谱特性和非线性光学性质的研究。其中bpy=2,2-bipirdine,l=imidazo[f]1.10-phenanthroline(IP),or2-pheny-limidazo[f]1,10-phenanthline (PIP)or PIP的衍生物。采用时间分辨的ns激光对这组Ru络合物在含水溶液中和与DNA结合的发光特性进行研究。实验结果表明,当在L上结合不同电子施主或受主基时,对[Ru(bpy)2L]2+的MLCT的发光强度和寿命都有很大的影响,同样DNA的插入也对此有影响。采用四波混频方法对其非线性光学特性进行了测量,由此推算出三阶极化系数和分子的三阶超极化系数。并讨论了不同配体对三阶非线性光学系数的影响。 相似文献
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The generation of optical phase-conjugate waves and the application of optical phase conjugation (OPC) to optical communication systems is described. The method of pulse shape distortion compensation by OPC is outlined including distortion due to both fiber dispersion and the optical Kerr effect. The generation of a forward-going phase-conjugate wave in a third-order nonlinear medium is discussed and that by a nondegenerate forward four-wave mixing in a zero-dispersion single-mode fiber (SMF) is investigated. Suppressing the stimulated Brillouin scattering (SBS) of a pump wave in the fiber prevents saturation of the generation efficiency of the phase-conjugate wave even when the pump power exceeds the SBS threshold. In transmission experiments through a 200-km standard SMF with a 16-Gb/s intensity-modulated signal and a 5-Gb/s continuous-phase FSK (CPFSK) modulated signal, it is shown the applicability of OPC is modulation independent and that OPC effectively compensates for both chromatic dispersion and the optical Kerr effect 相似文献
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Ulmer T.G. Hanna M. Washburn B.R. Ralph S.E. SpringThorpe A.J. 《Quantum Electronics, IEEE Journal of》2002,38(1):19-30
By incorporating an integrated microcavity into an optical waveguide structure with vertical quasi-phase-matching, we have realized surface-emitted second-harmonic generation devices that significantly enhance the conversion efficiency for optical pulses in the picosecond and sub-picosecond regimes. We demonstrate both theoretically and experimentally that nonlinear interactions involving short optical pulses can be enhanced by a microcavity, even when the resonance width is substantially narrower than the spectral content of the pulse. The resulting enhancement enables practical signal processing functions such as ultrafast optical time-division demultiplexing at 1.55 μm in multilayer AlGaAs structures 相似文献
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Inouye H. Arakawa M. Jing Yong Ye Hattori T. Nakatsuka H. Hirao K. 《Quantum Electronics, IEEE Journal of》2002,38(7):867-871
We produced an asymmetric Fabry-Perot microcavity using total reflection, and its optical properties were investigated. The structure is considered to be a total-reflection-type 1-D photonic crystal. An electric-field enhancement of incident light in a defect layer installed inside the photonic crystal was observed by fluorescence emission from dye molecules doped into the defect layer division. We confirmed that the incident light intensity was strengthened by about 63 times in the defect layer 相似文献
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Z. Yang L. Mutter M. Stillhart B. Ruiz S. Aravazhi M. Jazbinsek A. Schneider V. Gramlich P. Günter 《Advanced functional materials》2007,17(13):2018-2023
We present new stilbazolium salt DSTMS (4‐N,N‐dimethylamino‐4′‐N′‐methyl‐stilbazolium 2,4,6‐trimethylbenzenesulfonate) with both high second‐order nonlinear optical properties and very favorable crystal growth characteristics. We are able to obtain very large area bulk single crystals of more than 3 × 3 × 0.2 cm3 with a high optical quality without using seed crystals by using low‐temperature solution growth. We also demonstrate the growth of single crystalline thin films of DSTMS with an area of up to 6 × 5 mm2 and a thickness between 5–30 μm. Nonlinear optical measurements reveal that DSTMS possesses large nonlinear optical susceptibilities with χ111(2) = (430 ± 40) pm V–1 at 1.9 μm. Highly efficient generation of broadband THz waves with THz electric field strengths of more than 4 kV cm–1 using 160 fs laser pump pulses at a wavelength λ = 1.45 μm and DSTMS crystals has been demonstrated. 相似文献
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J. J. CHOI R. M. GILGENBACH T. A. SPENCER 《International Journal of Electronics》2013,100(5-6):1045-1066
We report an experimental study on mode competition in a high-g Bragg resonator cyclotron resonance maser (CRM) employing a microsecond, relativistic electron beam. The high quality annular electron beam of 20-80 A was produced through an apertured mask-anode. The high-Q Bragg resonator was designed to excite the TE31, mode CARM oscillation at 18-9GHz. Two configurations of Bragg resonators were used; with ripples half inward and with ripples fully outward with respect to a smooth tubular centre section. Bragg resonator microwave emission was compared to radiation emitted when the electron beam interacted with smooth tubes with the same diameter as the Bragg resonator centre sections. In the present Bragg resonator CRM experiments, three parasitic oscillations were the most serious competing modes, apparently suppressing the TE31 CARM oscillation: TE21, absolute instability, TE11 gyro-BWO, second and third harmonic TE51, mode. When a high current annular beam of 150-200 A was injected into the Bragg resonator, we observed the TE21 absolute instability at B≥6-9kG, and a TE11 gyro-BWO interaction at B≤5-2kG. Experimental evidence on the modes of the absolute instabilities were provided by gas breakdown patterns in fluorescent light tubes and frequency measurements. 相似文献
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Photoluminescence and optical-reflection spectra of a periodic structure consisting of 60 tunneling-isolated GaAs quantum
wells separated by AlGaAs barriers are studied. The structure is designed so that, for a certain angle of incidence (∼23°),
the Bragg resonance condition is satisfied for light with a photon energy equal to the energy of heavy-hole excitons at the
second quantum-confinement level in the wells. It is established experimentally that, under the conditions of double exciton-polariton
and Bragg resonance, a superradiant optical mode is formed. Dependences of Bragg and exciton-polariton reflection on the angle
of incidence and polarization of light and the temperature are investigated. 相似文献
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提出了一种新型基于法布里 -珀罗 (F- P)微腔的发光器件结构 .它采用 PECVD方法制备的非晶硅 /二氧化硅结构作为微腔中的布拉格反射腔 ,非晶碳化硅薄膜作为中间光发射层 ,通过对一维方向光子的限制 ,使发光层荧光强度增强 ,谱线变窄 .通过调节发光层和反射腔膜厚及折射率 ,可以精确控制发光峰位 .实验结果证明该结构可望实现全硅基材料的强室温可见光发射 . 相似文献
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Omar A. M. Abdelraouf Aravind P. Anthur Zhaogang Dong Hailong Liu Qian Wang Leonid Krivitsky Xiao Renshaw Wang Qi Jie Wang Hong Liu 《Advanced functional materials》2021,31(48):2104627
Hybrid dielectric metasurfaces have emerged as a promising approach to enhancing near field confinement and thus high optical nonlinearity by utilizing low loss dielectric rather than relatively high loss metallic resonators. A wider range of applications can be realized if more design dimensions can be provided from material and fabrication perspectives to allow dynamic control of light. Here, tunable third harmonic generation (THG) via hybrid metasurfaces with phase change material Ge2Sb2Te5 (GST) deposited on top of amorphous silicon metasurfaces is demonstrated. Fano resonance is excited to confine the incident light inside the hybrid metasurfaces, and an experimental quality factor (Q-factor ≈ 125) is achieved at the fundamental pump wavelength around 1210 nm. Not only the switching between a turn-on state of Fano resonance in the amorphous state of GST and a turn-off state in its crystalline state are demonstrated, but also gradual multistate tuning of THG emission at its intermediate states. A high THG conversion efficiency of η = 2.9 × 10−6% is achieved, which is 32 times more than that of a GST-based Fabry–Pèrot cavity under a similar pump laser power. Experimental results show the potential of exploring GST-based hybrid dielectric metasurfaces for tunable nonlinear optical devices. 相似文献
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Kunizo Ohkubo Teruo Saito Yuusuke Yamaguchi Yoshinori Tatematsu Jun Kasa Shin Kubo Takashi Shimozuma Kenji Tanaka Masaki Nishiura 《Journal of Infrared, Millimeter and Terahertz Waves》2017,38(7):853-873
We studied the transmission characteristics of hybrid modes in a corrugated circular waveguide above the Bragg frequency to develop a broad-band transmission line for millimeter waves. Millimeter waves at 294 GHz were transmitted into a straight waveguide. From observed power profiles in waveguide cross-sections, a high attenuation rate of 0.13 dB/m was obtained. To match a theoretical attenuation constant with the experimental one, we introduced an ad hoc coefficient of conventional surface reactance in the waveguide wall. This was necessary because the wall began to look like the surface with a decreasing anisotropic reactance owing to the frequency above the Bragg frequency. Using nonlinear optimization for mode content analysis, the observed power profiles in the waveguide cross-section were matched with theoretical profiles. There was good agreement between the calculated and observed centers of power profiles and attenuation rate along the waveguide. The theoretical analysis showed that the magnetic field at the waveguide wall increases and the substantial attenuation takes place. Above the Bragg frequency coupling to backwards propagating modes is a point of consideration. A combination of the backwards propagating EH1,26 and the forward propagating HE11 modes satisfied the Bragg condition at 294.7 GHz which was the nearest frequency of operating frequency. A strong attenuation of the incoming HE11 mode by Bragg resonance was not expected due to large difference of 0.7 GHz. It becomes clear that the observed high transmission loss outside of the Bragg resonance can be explained by a decrease in anisotropic surface reactance at the wall. 相似文献
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In this paper, a new 2-D frequency converter based on second harmonic generation (SHG) in GaAs photonic crystal waveguides is proposed. The input waveguide, where the second order nonlinear process takes place, is coupled to a secondary waveguide that is designed to allow only SH propagation. A row of photonic crystal microcavity resonators is then placed parallel to the waveguides in order to assist the field coupling. By tuning the resonance of the microcavities at second harmonic wave, the waveguides-microcavities arrangement showed good enhancement of conversion efficiency and selectivity. The performance of the proposed frequency converter has been analyzed by using multiresolution time domain (MRTD) scheme developed for nonlinear problems in conjunction with uniaxial perfectly matched layer (UPML) boundary conditions that rigorously truncate the computational window. 相似文献
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Experimental study on an all-optical switching based on MF-NOLM 总被引:1,自引:0,他引:1
Microstructure fiber ( MF) hasin recent years attrac-ted much scientific and technical interest . MF has arange of unique optical characteristics[1-3],such as singlemode guidance at all wavelengths ,fibers withanomalousdispersioninthe visible spectrum,and… 相似文献
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In conventional semiconductor lasers, the dimensions of the optical cavity greatly exceed the photon wavelength, and the photon density of states forms a continuum since it is essentially that of a bulk system. On the other hand, in an ideal laser, one would like to have a single optical mode coincident with the maximum in the gain spectrum of the active medium. We show that substantial density-of-states quantization and enhancement of the fraction of photons spontaneously emitted into the lasing mode can be obtained by reducing the lateral width of the surface-emitting laser. For emission at λ=0.954 μm, the threshold current density can be drastically reduced by increasing the coupling factor to a few percent. For a cavity structure width of 0.3 μm, the threshold current density is 50 A/cm2, compared with 250 A/cm2 for the 0.6-μm cavity. At lower still lateral widths, the cavity loses its vertical character, and confinement of the lateral optical mode rapidly deteriorates. The large-signal response of microcavity lasers is slightly improved primarily due to elimination of mode competition in intrinsically single-mode microcavities, with relaxation times close to 1 ns. The enhancement of the spontaneous emission coupling factor results in an increase of the relaxation oscillation frequency and improvement in the standard small-signal response of microcavity lasers. For J=10Jth, the -3 dB modulation frequency exceeds 40 GHz. Since low threshold current densities may be achieved in microcavity lasers, the gains in small-signal performance are primarily extrinsic, i.e., higher modulation bandwidths ace accessible for the same injection 相似文献