共查询到19条相似文献,搜索用时 475 毫秒
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理论分析了利用马赫-曾德干涉仪及平衡零拍探测技术测量相干介质色散特性的方法,实验测量了三能级铯原子分别在电磁诱导透明和电磁诱导吸收两种截然相反的相干效应下的色散特性.研究表明:在原子频率共振中心,对于透明介质,由于吸收减弱效应,信号光能穿出介质,保证了有效色散信息,即正常色散特性能被测量到;相反地,对于吸收介质,由于强吸收效应,只有在低粒子数密度条件下,即保证有信号光没有被完全吸收而穿出介质,才能测量到介质的反常色散特性;当提高铯泡温度时,介质对信号光吸收增强以至完全吸收,并且吸收频谱宽度变宽,导致色散信息不能被有效测量到. 相似文献
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本文设计了一种基于同心纳米圆环谐振腔的金属-介质-金属(MIM)表面等离子体光波导(SPW),其中外侧是一个完整的环形谐振腔,而内侧环形谐振腔带有一个微小缺口。利用数值和解析方法分析了不同几何参数下的传输特性。可以发现,当缺口宽度θ=5°,位置φ=45°时,会在波长674nm处产生明显的等离子体诱导吸收(Plasmonic Induced Absorption,PIA)现象。基于此,首先研究了该结构在折射率传感器方面的应用,研究结果表明,其灵敏度超过600nm/RIU,最大品质因子约为700。其次研究了其快光和慢光特性,在PIA传输谷处会产生约-0.081ps的光学延迟,意味着较大的异常色散和快光效应,而在PIA传输谷两侧的传输峰处会分别产生约为0.045ps和0.043ps的光学延迟,意味着较大的正常色散和慢光效应。这种表面等离子体光波导结构在折射率传感器、纳米滤波器、光开关和片上纳米光学器件集成等领域有一定的应用前景。 相似文献
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研究了单光子晶体界面介质波导中的慢光效应.芯层-空气层界面的全内反射效应以及光子晶体基底的禁带效应共同形成了对光场能量的横向约束.用基于超元胞的平面波展开法计算得到了导模色散曲线,并据此对其色散、群速以及群速色散性质做了详尽分析.由于利用了色散曲线慢光区域内拐点附近低群速色散的部分,该单光子晶体界面介质波导具有良好的慢光特性.对两个不同导模计算得到的平均群速分别为c/98和c/376,可用相对频带宽度分别达到2.1×10-3和4.1×10-4.另外,该慢光结构可以侧向耦合的方式克服光子晶体慢光波导耦合困难的缺点. 相似文献
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矩形孔光子晶体波导慢光特性 总被引:1,自引:0,他引:1
在线缺陷光子晶体波导中,利用矩形孔和椭圆孔分别替代临近线缺陷的第二行和第一、三行圆形孔,构成矩形孔光子晶体波导结构.利用平面波展开法对波导的慢光特性进行仿真分析,研究矩形孔的非对称性对慢光带宽和色散特性的影响.研究表明,在慢光区域平均群折射率变化为±10%的情况下,与圆形孔线缺陷波导相比,得到的导模能更好地限制在禁带中,而且当矩形孔宽度参量小于高度参量时,导模可以得到归一化延迟带宽积更大、带宽更宽、色散更小的慢光.通过对波导中矩形孔参量的优化,得到的慢光归一化延迟带宽积最大为0.402,此时带宽为44.4nm,群速度色散为8.0ps2/mm. 相似文献
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A slow light structure Mach-Zehnder fiber interferometer is theoretically demonstrated. The sensitivity of the interferometer is significantly enhanced by the dispersion of the slow light structure. The numerical results show that the sensitivity enhancement factor varies with the coupling coefficient and reaches its maximum under critical coupling conditions. 相似文献
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We demonstrate experimentally that the spectral sensitivity of an interferometer can be greatly enhanced by introducing a slow-light medium into it. The experimental results agree very well with theoretical predictions that the enhancement factor of the spectral sensitivity is equal to the group index n(g) of the slow-light medium. 相似文献
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We demonstrate theoretically and experimentally that the sensitivity of a fiber Mach-Zehnder (M-Z) interferometer can be enhanced by coupling fiber ring resonators with it. The experimental results agree well with theoretical predications that combining slow light with fast light will further increase the sensitivity of a fiber M-Z interferometer. 相似文献
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By performing optical two-wave mixing in a liquid crystal light valve, we are able to slow down optical pulses to group velocities
as slow as a few tenths of mm/s, corresponding to a very large group index. We present experiment and model of the slow light
process occurring in liquid crystal light valves. The large group index corresponds to having a large sensitivity for phase
variations, a property that can be used to increase the sensitivity of Fourier transform interferometer. We show that when
a liquid crystal light valve is inserted in a Mach–Zehnder interferometer, the effect of frequency perturbations at the input
of the system is amplified by a factor related to the group delay. 相似文献
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P. G. Eliseev 《Opto-Electronics Review》2008,16(2):118-123
A nonlinear wave interaction is considered as a technique to increase the rotation sensitivity of the ring laser. The gyroscopic
scale factor K is calculated in an active laser gyro with a dispersive medium. K is in reverse proportion to the group index
n* = n + vdn/dv of the medium. In a monolithically-integrated GaAs ring laser, the value K ∼5000 is obtainable (radius ∼1
cm) in a linear case. In the presence of a strong wave, the dynamic nonlinear anomalous dispersion can provide an increase
of K by 10–100 times in the vicinity of critical points where n* passes zero. An expression of K is derived for the nonlinear
Sagnac effect. The nonlinear dispersion is discussed in terms of “slow/fast” light. 相似文献
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A micro-scale Fabry–Perot interferometer with high spectral resolution and tunable transmission frequency is proposed. In this scheme, two partially reflecting mirrors with a separation of several wavelengths is fabricated in a waveguide, and a two-level emitter is located between the mirrors and coupled to the waveguide with chiral interaction. We analytically show that the single emitter plays the role of a strongly dispersive medium and the full width at half maximum (FWHM) of the transmission fringes around the resonance frequency of the emitter can be narrowed by 5 orders of magnitude. The proposed micro-scale interferometer can have the same spectral resolution as meter-scale traditional interferometers. We also show that the central frequency of the narrowed transmission fringe can be tuned by adjusting the asymmetry of the emitter-waveguide coupling. Our scheme has potential applications in the fields of integrated optical circuit and quantum information processing. 相似文献
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Slow and fast light: basic concepts and recent advancements based on nonlinear wave‐mixing processes
U. Bortolozzo S. Residori J.‐P. Pierre Huignard 《Laser \u0026amp; Photonics Reviews》2010,4(4):483-498
After a review of the basic concepts of slow and fast light, recent advancements based on nonlinear wave‐mixing processes are described. As a nonlinear medium, the authors focus on a liquid crystal light valve showing that it allows obtaining a large control of the group delay, with a maximum fractional delay of 1, and a deceleration of light pulses down to group velocities as small as 0.2 mm/s. A theoretical model accompanies the observations and accounts for them in the general framework of two‐wave mixing in the light valve. At the end, a high‐sensitivity interferometer is presented as an example of slow light applications. 相似文献
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Dispersive Properties of tunnelling—induced transparency in an asymmetric double quantum well 下载免费PDF全文
We have investigated the dispersive properties of tunnelling-induced transparency in asymmetric double quantum well structures where two excited states are coupled by resonant tunnelling through a thin barrier in a three-level system of electronic subbands. The intersubband transitions exhibit high dispersion at zero absorption, which leads to the slow light velocity in this medium as compared with that in vacuum (c=3×108). The group velocity in a specific GaAs/AlGaAs sample is calculated to be vg=c/4.30. This structure can be used to compensate for the dispersion and energy loss in fibre optical communications. 相似文献