TM-Mode selective filter using leaky waveguide structure.

In this paper, a structure using the optical leakage phenomenon is proposed as a relatively simple TM mode selective filter for optical circuits. The filter characteristics are discussed. In the TM mode selective filter discussed herein, a layer with refractive index higher than that of the waveguide layer (guided layer) is used as a cladding together with a thin buffer layer with a lower refractive index (ultralow-refractive-index layer). The cladding material used to realize a TM mode selective filter need not be a lossy material such as a metal with a so-called complex index of refraction. A layer with a refractive index equal to or higher than that of the guiding layer suffices. In this paper, it is shown with specific configuration examples (partly numerical examples) that an optical leakage structure with an ultralow-refractive-index buffer layer can exhibit excellent TM mode selective filter characteristics. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 85(8): 9–15, 2002; Published online in Wiley InterScience (<URL>www.interscience.wiley.com</URL>). DOI 10.1002/ecjb.10037 [ABSTRACT FROM AUTHOR]