Applications of light-matter interaction in nanosciences

Abstract

In this thesis, light matter interaction in nanoscale has been studied from various aspects. The interaction between surface plasmon polaritons (SPPs) and optically active organic molecules (Rhodamine 6G, Sulforhodamine 101 and Coumarine 30) and semiconducting nanocrystals (quantum dots) is studied in the weak coupling regime. In particular, a photon-SPP-photon conversion with spatially separated inand outcoupling was demonstrated by using molecules. Also, a frequency downconversion for propagating SPPs was presented by utilization of vibrational relaxation of organic molecules. A strong coupling regime was reached for Rhodamine 6G (R6G) and SPP despite the broad absorption linewidth of R6G. This implies that the regime is readily accessible for a wide variety of other molecule-SPP systems as well. In this context, two novel detection methods were introduced, which enable the studies of the system time evolution, information which has been inaccessible in previous studies. For the first time, a quantum mechanical hybridization of two molecular excitations and SPP was presented. Finally, in analogy to tunable-Q optical microcavities, it was shown that the strong coupling can be controlled by adjusting the interaction time between waveguided SPPs and R6G deposited on top of the SPP waveguide. The method allows studying extremely nonadiabatic phenomena in strongly coupled systems, since the interaction time can be controlled with sub-fs precision simply by adjusting the length of the R6G area by standard lithography methods. Also, a high throughput pattern transfer method for nanoscale objects was introduced, and the proof-of-principle experiment was done using quantum dots. The reported method is extremely robust due to the wealth of trapping force in the system. In addition to high precision and high throughput, the method enables dynamic control over the manipulation of objects and transferred pattern; one single universal master stamp can be used to generate any desired multicomponent pattern to the target plate. In addition, a method for fabricating ultra high vacuum compatible electrical feedthroughs for Bose-Einstein condensate (BEC) atom trapping chip was introduced. The method takes advantage of the electroplating technology together with the mass fabrication capabilities inherent in UV lithography, enabling the fabrication of on-chip ultra high vacuum sealable feedthroughs, small enough to have dozens of them on a single chip, but large enough to stand high currents necessary for the realization of BEC in such a configuration.