Defects in Photonic Crystals are of high interest because they can form microcavities with a modal volume down to the ultimate limit (lambda/2n)3, where lambda is the wavlength of the light and n the refractive index of the material. We have investigated Photonic Crystals made of macroporous silicon which contain point defects and linear defects [1]. A widely tunable continuous wave Optical Parametric Oscillator was used to perform transmission measurements. We recorded a resonance in the transmission spectrum due to a point defect [2] and found a good agreement with the theory for the resonance frequency [3]. We will discuss the influence of the fabrication parameters and geometry of the structure on the spectra. Beside the spectral investigations we have examined the spatial confinement of light in defect modes by local coupling and detection.
[1] Birner et al., Phys. Stat. Sol., 165, 111 (1998).
[2] P. Kramper, J. Mlynek, V. Sandoghdar, A. Birner, R. Wehrspohn, J. Schilling. U. Gösele, in preparation.
[3] Private Communication: M. Agio and C. Soukoulis.