10 likes | 131 Views
Penn State MRSEC: Center for Molecular Nanofabrication and Devices Mallouk T.E. DMR-0213623 Novel Electroactive Materials and Tunable Photonic Crystals.
E N D
Penn State MRSEC: Center for Molecular Nanofabrication and DevicesMallouk T.E. DMR-0213623Novel Electroactive Materials and Tunable Photonic Crystals Photonic crystals with large tunability are attractive for many important operations in optic communications including programmable filters, dynamic gain equalization and chromatic dispersion compensation. Among various methods, electric filed induced tuning offers many advantages. One challenge in achieving large tuning range by external fields in photonic crystals is the small strain (<0.1%) or refractive index change (<0.1%) in the currently available electroactive materials. Recently, based on first principles calculations, we predicted that there is a large electro-optic (E-O) effect in a P(VDF-TrFE) based polymer when undergoing a conformational change between the polar and nonpolar forms (refractive index change ~ 10%). Indeed, we show that in P(VDF-TrFE-CFE) terpolymer in which a small amount of chlorinated termonomer is copolymerized with P(VDF-TrFE) to modify the phase stability between different conformations and create nano-polar phases, a large E-O effect can be realized. Furthermore, the terpolymer also exhibits large electrostrictive strain (Figure 1). Utilizing the P(VDF-TrFE-CFE) terpolymer, a 1.5D photonic crystal – a long period fiber grating (LPFG) is under investigation in which a refractive index change in the cladding can result in a large tuning. Photonic crystals with defects modes will be investigated in which the large tuning available can produce switching in the guided modes. Figure 1. (a) FT-IR data under different electric field, showing large refractive index change (the shift of the inference pattern with field); (b) Electrostrictive strain; (c) Long period fiber grating and simulated tuning due to index change; (d) Defect mode tuning in 2-D photonic crystals. D. Jeong, Q. Chen, Y. Wang, Q. M. Zhang, V. Gopalan, S. Yin (PSU) G. Kavarnos (URI and NUWC)