A spatially-variant photonic crystal (SVPC) that can control the spatial propagation of electromagnetic waves in three
dimensions with high polarization sensitivity was fabricated and characterized. The geometric attributes of the SVPC
lattice were spatially varied to make use of the directional phenomena of self-collimation to tightly bend an unguided
beam coherently through a 90 degree angle. Both the lattice spacing and the fill factor of the SVPC were maintained to
be nearly constant throughout the structure. A finite-difference frequency-domain computational method confirms that
the SVPC can self-collimate and bend light without significant diffuse scatter caused by the bend. The SVPC was
fabricated using multi-photon direct laser writing in the photo-polymer SU-8. Mid-infrared light having a vacuum
wavelength of λ0 = 2.94 μm was used to experimentally characterize the SVPCs by scanning the sides of the structure
with optical fibers and measuring the intensity of light emanating from each face. Results show that the SVPC is
capable of directing power flow of one polarization through a 90-degree turn, confirming the self-collimating and
polarization selective light-guiding properties of the structures.
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Jennefir L. Digaum ; Javier Pazos ; Raymond Rumpf ; Jeff Chiles ; Sasan Fathpour, et al.
Polarization sensitive beam bending using a spatially variant photonic crystal
", Proc. SPIE 9371, Photonic and Phononic Properties of Engineered Nanostructures V, 93710I (February 27, 2015); doi:10.1117/12.2076829; http://dx.doi.org/10.1117/12.2076829