TOP Research Themes & Directions

1. Overview

Light fields are commonly viewed as purely deterministic, spatially and/or temporarily fully coherent entities. Realistic optical sources, however, comprise myriads of atoms emitting light more or less independently of one another. As a result, such sources are naturally noisy, imposing a fundamental limit to optical field coherence. Our group examines novel statistical (noisy) light sources within the framework of linear and nonlinear statistical optics and plasmonics.
Statistical optics. - Perhaps counterintuitively, the presence of noise can open up avenues for designing novel light sources with superior properties, tailored to specific applications. For instance, noisy or partially coherent sources are known to be stable to environment fluctuations such as medium turbulence or presence of impurities. More important, the noisy nature of light sources can lead to new physical phenomena such as random soliton or rogue wave (RW) formation in nonlinear optical systems. RWs, the waves of anomalously large amplitudes arising in noisy environments as diverse as stormy oceans and nonlinear optical fibers, are statistically rare but significant events that have been discovered in physics, engineering, oceanography, and stock market dynamics to mention but a few disciplines. The TOP aims to understand RW formation in optical systems and apply the lessons we can learn from optics to (a) elucidate the RW universal physical nature, (b) engineer RW properties and (c) explore their potential applications. We also design novel partially coherent light pulses and beams for a variety of applications, including free-space and fiber optical communications, energy/information transfer, optical computing as well as nano-particle trapping and transport.
Statistical plasmonics. - Plasmonics is concerned with the behaviour of surface electromagnetic waves, the so-called surface plasmon polaritons, that can be excited at metal- dielectric interfaces. Our group has recently advanced the concept of polychromatic, partially coherent surface plasmon polaritons. We are currently exploring salient physical characteristics of such waves as well as their experimental realization and useful applications in a variety of plasmonic settings. Finally, we explore surface nonlinear optical effects to design ultra-accurate sensors for bio-medical, environmental, or national security applications.

2. Recent research highlights

1. Rogue waves in stimulated Raman scattering. We have recently explored RW excitation in stimulated Raman scattering, triggered in gas-filled hollow core photonic crystal fibers (HCPCF) by noisy Stokes input pulses. As is exhibited in Fig. 1, non-Gaussian statistics of the peak Stokes pulse power-a signature of RW formation-is strongly affected by the input Stokes pulse coherence time Tc measured in the units of the pulse width T0.


2. Difference-frequency wave (DFW) excitation at metal-air interface and surface sensors. We have lately examined the DFW spectrum generated at a metal-air interface, concurrent with the surface plasmon polariton excitation, when the latter is illuminated with a polychromatic light source. The discovered giant spectral transformations of the excited DFWs, shown in Fig.2, can be utilized to design ultra-accurate surface sensors.