Open AccessNear-field observation of anomalous optical propagation in photonic crystal coupled-cavity waveguides
Author(s) -
Haihua Tao,
Cheng Ren,
Ya-Zhao Liu,
Qingkang Wang,
Daozhong Zhang,
Zhiyuan Li
Publication year - 2010
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.18.023994
Subject(s) - optics , photonic crystal , near field scanning optical microscope , waveguide , wavelength , materials science , normal mode , eigenmode expansion , optoelectronics , physics , optical microscope , scanning electron microscope , vibration , quantum mechanics
An air-bridged silicon-based photonic crystal coupled-cavity waveguide (PCCCW) connected with an input and output W1 PC waveguide (PCW) was designed and fabricated. We mapped its intensity distributions with a near-field scanning optical microscope (NSOM) at near-infrared wavelengths around 1550 nm. Surprisingly, the intensity distributions demonstrate that the second odd eigenmode dominates in such a PCCCW, even though it possesses a much slower group velocity of light than that of the first even one. Further considering the measured transmission spectrum, we find that the modal profile and impedance matching between the eigenmodes in the PCW and PCCCW plays an important role in the optical propagation efficiency. Mode conversion between the first even and the second odd eigenmode was also detected at the interfaces between the W1 PCW and PCCCW.