Field-of-view expander for optical receivers exploiting the negative refractive behavior of photonic crystals

We present an unconventional approach to counteract the spreading of the illumination area in the focal plane of a lens due to an aberrated optical beam by exploiting the negative refractive behavior of photonic crystals. We design a photonic crystal structure and analyze its dispersion property with respect to its effective refraction index. This result is confirmed by electromagnetic analysis using the FDTD method. As an application of this device, we take a look at free-space optical communications and propose a field-of-view expander for optical receivers. A proof-of-principle calculation of our idea is performed by the ray trace method. Results show that the spreading is reduced by more than 90% without expansion of the propagation beam angles.