Non-polarizing single layer inorganic and double layer organic-inorganic one-dimensional guided mode resonance filters

Guided mode resonance (GMRF) phenomena occurs when the evanescent orders of a diffraction grating are coupled to the waveguide modes and propagate out at given optical parameters such as wavelength, angle, and state of polarization of incident light. The outcoupling field from a waveguide is, in general, polarization sensitive. Polarization insensitive 1D subwavelength grating structures with high diffraction efficiency at normal and oblique incidence are required, for example, in optical communications where output light may possess any polarization state. This means that an s- or p-polarized input optical field, which generally couples TE- or TM-modes in the waveguide under different resonance conditions, can be tuned at one resonance by selecting suitable grating parameters, regardless of the input polarization state. All of the polarization insensitive devices fabricated to date either employing a method which is not cost-effective or simple enough to some extent. In this work, we report the design and fabrication of two types of non-polarizing binary-structured one-dimensional (1D) GMRF at normal incidence. A single layer binary-profile TiO2 resonant grating (grating-I) is fabricated by Atomic layer deposition (ALD), electron beam lithography (EBL) and reactive ion etching (RIE), which demonstrates almost perfect non-polarizing filtering effect with 1D grating under normal incidence. A double layer rectangular-profile polycarbonate-TiO2 1D GMR grating (grating-II) is fabricated by nanoimprint lithography (NIL) and ALD which also shows good non-polarizing property and the potential of cost-effective mass fabrication of such functional devices.