1. Engineering Spontaneous Emission in Hybrid Nanoscale Materials for Optoelectronics and Bio-photonics Arup Neogi Department of Physics and Materials Engineering University of North Texas Email: arup@unt.edu

3. Ultrafast and Nanoscale Photonics Group Arup Neogi, Department of Physics Research Areas 1.Nanoscale Optoelectronic materials for efficient light emission 2.Biophotonic materials; for hybrid molecular electronics and photonics http://www.phys.unt.edu/research/photonic/website/ Funding: National Science Foundation US Department of Energy Japan Soc. for Promotion of Sciences

4. Using subwavelength corrugated surface grating: Momentum can be transferred to couple the light and plasmon modes Directional Emission can be improved by using corrugated surfaces Surface plasmons polariton coupling with directional emission

5. Change in radiative recombination lifetime in Qdots due to resonant exciton-surface plasmon coupling Radiative recombination rate in strained quantum dots emission - observed above the SP emission energy

6. Energy Transfer in Quantum Dots entrapped in Hydrogel Microspheres Arup Neogi, Zhibing Hu Department of Physics University of North Texas

7. Temperature induced changes in hydrogel The NIPAM sample in water: Effect of temperature 61 21 o C35 o C 1 cm The phase transition temperature (T c ) of PNIPAM is 34 °C. below T c, the hydrogel is hydrophilic and swells in water, while above T c it is hydrophobic and collapses into a small volume.

8. Change in scattering properties with particle size Variation of Particle size with chemistryChange in scattering properties with turbidity

9. Photoluminescence Spectrum of QDs embedded in GEL UV Sunlight The image of PNIPAM/CdTe microgel under sunlight The PL image of PNIPAM/CdTe microgel under UV lamp.

10. Electric Field Induced effects in PNIPA Gels *Wu, J. et. al. Phys. Rev. Lett., 90, 48304 (2003) + Hu, Z. et. al. Advan. Mater. 13, 1708 (2001) At room temperature No electric field 3.5V/cm electric field