量子光学学报, 2010, 16 (4): 300, 网络出版: 2011-01-26
蝴蝶形中空表面等离子体波导的传输特性
Propagation Properties of a Surface PlasmonicWaveguide with a Butterfly Air Cores
摘要
本文设计了一种蝴蝶形中空表面等离子体波导,并对其传输特性进行了研究。采用频域有限差分法,对这种波导所支持的基模的能流密度分布、有效折射率、传播长度和模式面积随几何参数和工作波长的变化关系进行了分析。结果表明:沿纵向的能流主要分布在由四个圆洞所构成的上下两个尖角之间的区域,且越接近尖角,沿纵向的能流越大。对中空圆洞的半径、上下两排圆洞圆心间横向距离和左右两列圆洞圆心间的纵向距离进行调节,模式的有效折射率、传播长度和模式面积也随之变化。在工作波长确定的条件下,相对于b=r/4的情况来说,当b=r/2时,上下两个尖角之间的距离较大,场与金属的相互作用较弱,有效折射率就较大,传播长度也较大。在几何参数确定的条件下,相对于λ=705.0 nm的情形来说,在λ较大时,场的分布范围较大,场与金属表面的接触面积较大,场与金属的相互作用较弱,有效折射率较小,传播距离较长。与由两个和三个空心圆柱构成芯区的表面等离子体波导相比较,蝴蝶形中空表面等离子体波导具有良好的传输特性。如果在波导结构中心填充增益介质,可以克服较大的传播损耗,因此这种蝴蝶形中空表面等离子体波导可以用于光子器件集成领域和传感器领域。
Abstract
A kind of surface plasmonic waveguide (SPW) with a butterfly air core is introduced, and its transmission performance is analyzed using the finite-difference frequency-domain (FDFD) method. The dependence of distribution of longitudinal energy flux density, effective index, propagation length and mode area of the fundamental mode with longer propagation length supported by this waveguide on geometrical parameters and working wavelengths are discussed. Results show that the longitudinal energy flux density distributes mainly in the upper and lower two sharp corners which are formed by four air cores, and the closer to the sharp corner the stronger the longitudinal energy flux density. The effective index, propagation length and mode area of the fundamental mode can be changed with regulating the radius of circular air cores, the lateral distance of the two rows cores as well as the longitudinal distance of two columns cores. At the certain working wavelength, relative to the case of b=r/4, in the case of b=r/2, the distance of the two upper and lower sharp corners is large, then the interaction of field and silver is weak, and the effective index increases, so the propagation length becomes large. With the certain geometric parameters, relative to the case of 705.0 nm, in the case of larger working wavelength, the area of field distribution is large, and the size of the contact area of field and metallic surface is also large, then the interaction of field and silver is weak, and the effective index decreases, so the propagation length becomes large. Compared with the SPWs which are composed of two and three circular air cores, our proposed SPW has better transmission performance. Finally, the possibility to overcome the large propagation loss by using a gain medium as core material is investigated. This kind of surface plasmonic waveguide can be applied to the field of photonic device integration and sensors.
段欣, 贾智鑫, 薛文瑞. 蝴蝶形中空表面等离子体波导的传输特性[J]. 量子光学学报, 2010, 16(4): 300. DUAN Xin, JIA Zhi-xin, XUE Wen-rui. Propagation Properties of a Surface PlasmonicWaveguide with a Butterfly Air Cores[J]. Acta Sinica Quantum Optica, 2010, 16(4): 300.