We have demonstrated strong multimode photonic microresonator and nanoparticle interactions by using an integrated micro disk resonator from through port of the laser coupling bus waveguide. In addition to the fundamental resonance mode, disk resonator has higher order resonance modes. The excited higher order mode has a node at the position where the electromagnetic energy of the fundamental mode is close to a maximum. Here we report that a self referencing mechanism can be achieved by simultaneous excitation of both fundamental and 2nd order micro disk optical resonance modes. Additionally, we are able to measure the area around the maximum of the fundamental resonance mode and the node of the higher order mode, which have overlaps in the disk. In this work, we used on chip disk microresonator as the example, as a variety of types of optical microresonators have been investigated; we used nanoparticle to interact with the two optical resonance modes excited by the coupling bus waveguide, where the nanoparticle can be either dielectric materials or metallic materials. The strong photonic microresonator and nanoparticle interactions have variety of applications for optical switches, waveguides and detection. The self-referencing characteristics of the two optical resonance modes have potential to achieve photonic functions independent of external perturbation, such as temperature change.

Two dimensional Er3+-TeO2 thin film photonics crystals (PhCs) are fabricated. These PhCs demonstrate broadband enhancement of PL emission at near Infrared (NIR). The PhC structures are written by dual beam focused ion beam (FIB). Highly uniformed patterns with smooth surfaces are observed. A pattern resolution better than hundred nanometers is achieved. PhCs arrays with photonic lattice constants from 350 nm to 1700 nm are examined in order to optimize the PL extraction efficiency. Strong photoluminescence around 1530 nm is observed by 488-532 nm lasers pumping. A confocal microscopy with spectrometer is used to capture the broadband PL signals from individual PhC array.

The emission enhancement factor and spectral dependent extraction ratio are analyzed to find the interaction between PL lightwave and PhC structures. By optimize the PhC structures, 1500 um-1560 um broadband PL is successfully converted between the PL emission layer and the external cavity. A 60 % enhancement of surface extraction efficiency is achieved when PhC with periodicity a=800 nm is applied. When photonic lattice constants a are smaller than the critical periodicity 600 nm, the PL light becomes confined inside the thin film layer. Simulation is also performed by two dimensional finite difference time domain (FDTD) calculation in order to explain the experimental observed anisotropic PL enhancements.

The broadband PL enhancement enables Er3+-TeO2 PhCs thin film as a potential light source for three dimensional integrated photonic circuits.

The effects of high concentration on the photophysical properties of a nonlinear material have been of interest for some time in our group. It is well known in the literature that for a nonlinear absorbing dye to be the most effective, high concentrations are needed. The problem is that most photophysical studies in solution are done at low concentration. These low concentration studies are important for understanding inherent materials properties but it is also important to understand what happens in a material at high concentration. In addition to this, efforts have been made to study the effects of incorporating a dye into a solid matrix environment to better understand the constraints this environment has to a given material. Preliminary results for a PMMA system reveal the formation of excimers (excited state dimers) with an increase in concentration. Excimers are forming from the triplet excited state of the E1-BTF. A rate constant for this formation is 2.3 x 106 M-1 s-1. While rather slow, at high concentration the excimer is readily formed. This must be considered when making nonlinear absorption measurements since the excimer will certainly contribute to the overall nonlinearity.

It has been found that the blue light emission of LED is remarkably enhanced by using optical window of CaF2 disk doped with Eu2O3. The CaF2 crystals doped with Eu2O3 strongly absorb UV light with 330~420nm optical wavelength as a cutting filter. Instead, CaF2 crystals emit 420~425nm wavelength visible light. As a result, the UV light shifts to a light of around 420nm wavelength, and the LED light emission intensity markedly increases. In our experiments, the UV components were absorbed, while, around 420nm emitting light has been strengthened by more than 30%. The FWHM value is improved by around 30%.

Using a self-assembly process, we fabricated ordered chains of transparent polystyrene microspheres that have 30°- and 60°-branched structures and that act as coupled-resonator optical waveguides (CROWs). We then observed the optical properties of propagation light through the CROWs. The light spectra were directly measured by guide-collection-mode near-field scanning optical microscopy (NSOM) techniques. The spectrum of light propagating to the 60°-branch shows some sharp peaks, which seem to be associated with whispering gallery modes (WGMs). On the other hand, the spectrum of light propagating to the 30°-branch shows rather broad peaks. Moreover, we observed the detailed structures of the CROWs by high-resolution scanning electron microscopy (HR-SEM), and performed a finite-difference time-domain (FDTD) simulation to explain the NSOM spectra. The results suggest that the microspheres’ branching chains themselves have a light-splitting function, which is a kind of wavelength-selective filter.