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NANO LASER. Lavinia P. Rajahram 18 th April 2014. Shrinking the laser!. A brief overview. An oscillator comprises: Amplifier with gain-saturation mechanism A feedback system A frequency-selection mechanism Output coupling scheme. SUB-WAVELENGTH DIMENSIONS!. Nano Laser - Background.
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NANO LASER Lavinia P. Rajahram 18th April 2014
A brief overview • An oscillator comprises: • Amplifier with gain-saturation mechanism • A feedback system • A frequency-selection mechanism • Output coupling scheme SUB-WAVELENGTH DIMENSIONS!
Nano Laser - Background • Concept developed by Mark Stockman in 2003 at Georgia State University. Theory is based on electron vibration rather than the traditional electron excitation • These vibrating electrons (called nanopendulums or plasmons) were not seen as of 2003. • In 2009, after almost 50 years of laser invention, Surface Plasmon Amplification by Stimulated Emission of Radiation(SPASER) was achieved. • To act like lasers a feedback system was required for the Surface Plasmon to oscillate back and forth so that they gain power and can be emitted as light
SPASER (2009) • Photons replaced by Surface Plasmon • Resonant cavity replaced by Nanoparticles • Energy source active gain medium excited externally
Photon Surface Plasmon • 44nm nanoparticle with gold core and dye doped silica shell • Surface plasmon resonance capable of squeezing optical frequency
SpASer Based nanolaser Nature, 27 August 2009
LASING IN METAMATERIAL NANOSTRUCTURES • Gain described by generic 4 level atomic system • Critical pumping rate to compensate losses in nanostructure Induced Radiation Rate or Excitation Rate depending on its sign! • Journal of Optic, Jan 2010
My current research • To understand fundamental properties of spontaneous emission altered by metamaterial • To understand the coupled nanostructure gain system (dealing with time dependent wave equations in metamaterial) • Coupling Maxwell’s equation with the Rate equation of electron populations • Starting with a 3 level atomic system code with FDTD formalization • Understanding parallel simulations
3 Level system • Maxwell + Rate Equation • Atomic transition dipole • Forth order Runge - Kutta Method • Finite – Difference Time Domain Method (FDTD)
PARALLEL Computation R2 = R1 + 10.25nm R1 = 20.25nm NY = 321 • Each rank has 20 grid • No of processor 16 • Scattered field zone at Rank 12 NX = 231