Microwave modeling of photonic crystals

• Applicant: Professor Dr.-Ing. Wolfgang Freude
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2001 to 2009
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5318328

Integrated optical filters are key components for high-capacity photonic networks with wavelength division multiplexing (WDM) near a wavelength of lambda_o = 1.55 µm (frequency f_o=193 THz). Integrateable optical filters, e.g., ring resonators in a silicon-on-silica technique, require a structural precision in the 10-nm range, while electron beam lithography has a practical resolution of only 30...50nm. Model experiments near f_m=10GHz need a much lower dimensional accuracy in the order of 10nm x f_o/f_x=0.2 mm, which can be easily achieved even with numerically controlled milling machines. We propose to investigate various periodic two-dimensional photonic crystal model structures at microwave frequencies for checking our design procedure. As a further benefit, we can measure the fields using electric or magnetic probes. The optical silica substrate is modeled by micro-fibre filled PTFE (teflon) with n²_PTFE = (1,48)²= 2.2 in the microwave case, the optical silicon waveguides are replaced with ceramic-filled PTFE having n²_cer= (3.3)²=10.8. Besides the modeling of periodic structures intended to be realized at optical frequencies, we plan to design photonic crystals for direct microwave use. We are especially interested in two-dimensional photonic bandgap structures for suppressing parasitic parallel plate modes which limit the bandwidth of planar microwave antenna arrays with optical feeder networks.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1113: Photonic Crystals
• Participating Person: Professor Dr. Kurt Busch