Crystalline Arrays of Nanoparticles for Controlling Flow of Light

Prof. B. V. R. Tata
Mon, 26th Nov, 2018 4:00 pmAdd to Calendar 2018-11-26 16:00:29 2018-11-26 16:00:29 Title Description Location IIT Palakkad UTC public
Mon, 26th Nov, 2018 5:00 pm

Advances in the synthesis of nearly monodisperse colloidal nanoparticles have made it possible
to fabricate crystalline arrays of nanoparticles (known popularly as Colloidal Nano Crystalline
Arrays (NCAs)) with lattice parameters close to the wavelength of light. Light travelling through
such crystals experiences a period variation of refractive index, analogous to periodic potential
energy of an electron in an atomic crystal. This variation in refractive index in three dimensions
with hundreds of nanometres periodicity is responsible for photonic band structure in these
crystals. Thus these crystals are also known as photonic crystals (PCs)/photonic band gap
(PBG) crystals and have several emerging applications such as Bragg diffraction devices,
optical filters and switches, photonic bio-sensors, non-bleachable display materials etc. Large
single crystalline domains are crucial for some of these applications and lithography based
approaches are unrealistic. Thus photonic band gap crystals have analogy with semiconductors
in band structure. The talk presents an overview of synthesis, characterization and self-
assembly methods employed in my group for fabricating NCAs of charged silica, polystyrene
and stimuli-responsive microgel particles. Issues involved in impregnating stimuli-responsive
microgel particles with semi-conductor quantum dots for fabricating photonic crystal alloys and
Holographic Optical Tweezers for fabricating seed photonic crystals of desired symmetry and
lattice constants will also be discussed

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