We report a tunable nanophotonic device concept based on flexible photonic crystal, which is comprised of a periodic array of high index dielectric material and a low index flexible polymer. Tunability is achieved by applying mechanical force with nano-/micro-electron-mechanical system actuators. The mechanical stress induces changes in the periodicity of the photonic crystal and consequently modifies the photonic band structure. To demonstrate the concept, we theoretically investigated the effect of mechanical stress on the anomalous refraction behavior and observed a very wide tunability in the beam propagation direction. Extensive experimental studies on fabrication and characterizations of the flexible photonic crystal structures were also carried out. High quality nanostructures were fabricated by e-beam lithography. Efficient coupling of laser beam and negative refraction in the flexible PC structures have been demonstrated. The new concept of tunable nanophotonic device provides a means to achieve real-time, dynamic control of photonic band structure and will thus expand the utility of photonic crystal structures in advanced nanophotonic systems.
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