Analysis of Metal-clad Planar Waveguide with Corrugated Long-period Gratings
The polarization characteristics of metal-coated long-period waveguide gratings (LPWG) are analyzed based on the coupled-mode theory. We consider a five-layer slab waveguide structure as shown in Fig. 1, which consists of a core layer of refractive index n1, two cladding layers of refractive index n2, and two thin metal films of refractive index n3 as the external layers. A corrugated long-period grating (LPG) of corrugation depth 2h and pitch A is formed on the surface of the core layer. We assume that the waveguide supports only the fundamental TE0 and TM0 modes. The LPG allows light coupling between the fundamental modes and the cladding Tem and TMm (m=1; 2; 3;:::) modes at discrete wavelengths. Since metals are generally characterized by a dieffectric constant that has a large and negative real part and a small imaginary part 1, 2, the effective index difference between the TE and TM polarizations of a metal-coated waveguide is larger than that of a dieffectric-coated waveguide 3. Therefore, a metal coating of index n3 is considered for the external medium so that the TE and TM polarizations are spectrally well-separated, and thus, can be seffected effectively. Through appropriate design of waveguide parameters, such as layer thickness, pitch, corrugation depth, and the refractive indices, we can obtain a polarization-seffective broadband reffection filter. Long-period waveguide gratings should find potential applications as integrated-optical filters and sensors.
Florence Y. M. Chan K. Yasumoto
Department of Computer Science and Communication Engineering, Kyushu University Fukuoka 819-0395, Japan
国际会议
Progress in Electromagnetics Research Symposium 2007(2007年电磁学研究新进展学术研讨会)(PIERS 2007)
北京
英文
1699
2007-03-26（万方平台首次上网日期，不代表论文的发表时间）