We present details of the fabrication, calculations, and transmission measurements for finite two-dimensional (2D) polymer photonic crystal (PC) slab waveguides, which were fabricated from a benzocyclobutene polymer on a low refractive index substrate from Teflon. A square air hole lattice (500 nm lattice constant, 300 nm hole diameter) was realized by electron beam lithography and reactive ion etching. Polarization and wavelength dependent transmission results show TE-like and TM-like stop gaps at 1.3 μm excitation wavelengths and are in good agreement with the calculated data obtained by 2D and three-dimensional finite difference time domain methods. Transmission was suppressed by 15 dB in the center of the TE-like stop gap for a PC length of ten lattice constants.

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We report on the feasibility and process parameters of nanoimprint lithography to fabricate low refractive index passive optical devices. Diffraction gratings printed in polymethylmethacrylate (PMMA) exhibit a sharp dispersion with a full width at half maximum of about 20 nm. Waveguides were printed in polystyrene (PS) on silicon oxide and had losses between 8-20 dB cm −1 at wavelengths between 650-400 nm, respectively. Finally, one-dimensional photonic structures were also printed in PS and their transmission and morphology characterized. The expected Bragg peak was observed in transmission and atomic force microscopy images have shown a good pattern transfer. A square lattice was printed in PMMA and more than 40 print cycles were obtained, i.e., potentially more than 1000 imprints from one master stamp.

Finite two-dimensional (2D)-photonic crystal slab waveguide structures from moderate refractive index materials have been investigated theoretically and results were compared with experimental data. 3D-finite difference time domain (3D-FDTD) simulations reveal a strong dependence of the transmission on the etching depth. For structures with etching depths less than the waveguide core thickness, both a substantial leakage of optical power to the substrate and a spatial mismatch of the transmitted field to the waveguide mode were found, leading to unsatisfactory transmissions. These losses occur mainly on the airband side of the spectrum where the optical field is concentrated in the holes. However, hole depths extending into the substrate by only 0.5 μm lead to an almost perfect mode match at transmission values exceeding 90%.

We have etched submicron holes into SiO2, Ta2O5, and Nb2O5. The etching process has produced walls with low roughness, less than <30 nm, for Ta2O5 and Nb2O5, and <10 nm for SiO2, which compares well to the NiCr mask hole edge roughness of 5–10 nm. Three-inch wafers with real photonic-crystal structures have been etched. The problems associated with the high sublimation temperatures of TaF5 and NbF5 have been solved by increasing the substrate surface temperature to above 120 °C. However, for the narrowest holes, about 250 nm across, a pulsed electron-cyclotron-resonance method has had to be used in addition, in order to see an etching effect.