Polymer lattices as mechanically tunable 3-dimensional photonic crystals operating in the infrared

Broadly tunable photonic crystals in the near-to mid-infrared region could find use in spectroscopy, non-invasive medical diagnosis, chemical and biological sensing, and military applications, but so far have not been widely realized. We report the fabrication and characterization of three-dimensional tunable photonic crystals composed of polymer nanolattices with an octahedron unit-cell geometry. These photonic crystals exhibit a strong peak in reflection in the mid-infrared that shifts substantially and reversibly with application of compressive uniaxial strain. A strain of similar to 40% results in a 2.2 mu m wavelength shift in the pseudo-stop band, from 7.3 mu m for the as- fabricated nanolattice to 5.1 mu m when strained. We found a linear relationship between the overall compressive strain in the photonic crystal and the resulting stopband shift, with a similar to 50 nm blueshift in the reflection peak position per percent increase in strain. These results suggest that architected nanolattices can serve as efficient three-dimensional mechanically tunable photonic crystals, providing a foundation for new opto-mechanical components and devices across infrared and possibly visible frequencies. (C) 2015 AIP Publishing LLC.