Frequency selective IR-filter produced by using EB-lithography

This paper reports on the fabrication of Jerusalem cross diplexer by direct write electron beam (EB) lithography followed by reactive ion etching (RIE) on a phosphorus doped polished silicon wafer substrate. Such structures can be used as frequency selective components in visible, microwave and near infra-red wavelength region. Replication of the patterns is accomplished by micron or sub-micron order mould fabricated from the silicon (Si) master. Fourier transform infra-red reflectance (FT-IR) measurements were performed to characterize the structured patterns. The spectral reflectance from these patterns clearly show a reflection dip due to surface plasmon excitation in the near infra-red wavelength at about 1.42 and 2.5 μm, respectively. Potential applications such as antireflection surface (ARS) can be realized.