Authors: C.M. Greiner, D. Iazikov, T.W. Mossberg, A. Ticknor and B. McGinnis
Affilation: LightSmyth Technologies, United States
Pages: 104 - 106
Keywords: nanophotonic filter, Bragg grating, apodization, DUV photolithography, planar lightwave circuit, waveguide, silica-on-silicon
Recent advances in deep ultra-violet (DUV) photolithographic patterning tools have enabled the scribing of essentially arbitrary diffractive structures with feature sizes even below 100 nm that can be precision-placed to within a few nanometers in a spatially coherent manner over several centimeters. For the fabrication of integrated nanophotonic filters based on etched waveguide Bragg gratings, this capability is especially empowering since it makes possible the control of reflective amplitude and phase of grating elements on a truly line-by-line basis thus providing unprecedented freedom in terms of engineering the filter’s spectral response. Here, we present results on spectrally engineered (apodized) grating filters that uniquely leverage the line-by-line control afforded by modern nanolithography. A variety of apodized channel waveguide gratings, relevant to filtering applications in coarse wavelength division multiplexing and fiber-to-the-premise, were fabricated in the silica-on-silicon platform. Excellent spectral transfer function characteristics such as very flat passbands, steep roll-off and adjacent channel isolation are demonstrated showcasing the powerful new apodization methods and high-fidelity fabrication based on DUV nanolithography.