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电磁波在周期介质中的传播及二维光子晶体的光子带结构 总被引:5,自引:4,他引:1
光子晶体是光学与凝聚态物理交叉的新领域,也是近年来应用物理学的一个重要研究领域,它是一种由介电常数高的(低的)介质在另一种介电常数低的(高的)背景介质中周期排列所组成的人造多维周期结构材料,能够产生光子带隙。频率落在带隙内的光在晶体里沿任何方向都不能传播,因而具有能够抑制原子、分子的自发辐射等诱人的光电子学特性,在基础研究和实际应用上都有着巨大的潜力。本文在这一领域里进行了富有成效的研究,获得了很好的结果。主要有:(1)利用平面波展开方法来计算二维光子晶体的带隙结构。首先,我们设计正方晶胞的二维光子晶体模型。设x3方向为介质柱的轴方向,二维周期结构在x1-x2平面上。晶胞的晶格常数为a,半径为r,介质柱和空气柱的介电常数分别为εa=17和εb=1,a>2r。设计的核心思想是通过降低光子晶体结构的对称性,消除光子能带在晶体的布里渊区高对称点上的本征简并。(2)对于二维光子晶体的电磁波理论及周期介质中的Bloch波解做了详细的推导,给出了光子晶体中禁带存在的理论依据。同时以正方格子晶格的二维光子晶体为例,验证了电介质在空气圆孔中的排列存在E偏振和H偏振的光子带隙重叠区,称为绝对光子带隙。对于二维的光子晶体,两种本征偏振模式的光子能带结构可以独立地调节,以实现两者的光子带隙的最优重叠, 从而大大提高了二维光子晶体的完全带隙宽度。 相似文献
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Nilesh J. Vasa Kouki Morishita Husayin Parhat Tatsuo Okada Mitsuo Maeda Osamu Uchino 《Optical Review》1997,4(1):A176-A179
Spectrally pure high-power tunable single-mode operation of a pulsed Ti3+:sapphire laser by a tunable injection-seeding is reported. The injection laser was a cw diode laser pumped, spectrally narrowed
tunable Cr3+:LiSrAlF6 (Cr3+:LiSAF) laser with a grating in the auxiliary cavity. Single-mode tunable operation of a pulsed Ti3+: sapphire ring oscillator was obtained at different wavelengths in the range between 818 nm and 848 nm with a typical linewidth
of 0.006 cm-1. To extend the applicability of this operation to a differential absorption lidar system, the single-mode Ti3+:sapphire oscillator output was amplified and a high energy output of 38 mJ was obtained with the same linewidth. 相似文献
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H. Parhat N.J. Vasa M. Kidosaki T. Okada M. Maeda T. Mizunami O. Uchino 《Applied physics. B, Lasers and optics》2000,70(3):361-366
We describe a comparative study related to an influence of a feedback coupling on operating characteristics of a cw Cr3+:LiSrAlF6 (Cr3+:LiSAF) laser using an end-coupled fiber grating with different coupling configurations. To achieve a compact construction,
a direct butt-coupling of the fiber grating at the pump end of the Cr3+:LiSAF laser and pumping through the same fiber was considered. The feedback provided by the coupled fiber grating through
an end mirror was responsible for a spectrally narrowed output with a slope efficiency of 11%. However, the performance critically
depended on an amount of the feedback coupling. The feedback-coupling condition was improved considerably by using a lens-coupled
fiber grating at the pump end of the Cr3+:LiSAF crystal. A spectrally narrowed output of ≈0.15 cm-1 was obtained, and the output slope efficiency was measured as 27%. Theoretical modeling was also performed to understand
the effect of the feedback coupling and the results agreed well with the experimental observations.
Received: 23 April 1999 / Revised version: 3 August 1999 / Published online: 30 November 1999 相似文献
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