IMR: Acquisition of Optical Instrumentation for Determination of the Band Structure of Photonic and Phononic Crystals and Education of Students

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This project is aimed at constructing two optical instruments in order to measure novel optical and acoustic properties of periodic polymeric materials. Specifically scientists at the MIT are interested in measuring both photonic and phononic dispersion relationships in self assembled block copolymers and photopolymers created by 3d interference lithography using high resolution magnetooptical rotation measurements and Brillouin light scattering. These two complementary types of measurement jointly rely on common physics (wave propagation in periodic media). Specifically the researchers will construct a high resolution Faraday polarization rotation apparatus comprised of an electromagnet system and a photoelastic modulator for the magnetooptical measurements and purchase a Brillouin light scattering apparatus, consisting of a Fabry-Perot interferometer and avalanche photodetector to enable the phononic dispersion curves to be measured. The realization of such experimental setups will enable scientists to test very exciting predictions of recent modeling studies conducted concerning 1D chiral photonic crystals containing magnetooptical nanoparticles being performed under NSF grant DMR#0308133 and to further recent work on phonon dispersion in 1D lamellar block copolymer crystals and 3d bicontinuous cubic network crystals made via interference lithography. The scientists have found a nondispersive optic-like mode related to the periodic variations in the mechanical properties, a clear indication of the behavior of a phononic crystal. Photonic crystals (materials that can guide the propagation of light, and in particular reflect certain colors) and phononic crystals (materials that can guide the propagation of sound, and in particular, reflect certain frequencies) both present basic scientific and potentially very technologically interesting materials. In this project scientsists at MIT will develop two related instruments to make new measurements of these interesting phenomena. Interactions between electromagnetic waves (light) or elastic waves (sound) in periodic materials can be surprising and useful. The researchers will make appropriate patterned polymeric crystals, model/simulate their properties using well developed theories and use the newly acquired instruments to access never before measured data for critical comparison to theory and for fundamental insight into to potentially revolutionary new devices: super thin prisms to spread out the colors of white light and open structures that one can see through but not hear through.