Nonlinear optical microscopy has enabled the possibility to explore inside the living organisms. It utilizes ultrashort laser pulse with long wavelength (greater than 800nm). Ultrashort pulse produces high peak power to induce nonlinear optical phenomenon such as two-photon excitation fluorescence (TPEF) and harmonic generations in the medium while maintaining relatively low average energy pre area. In plant developmental biology, confocal microscopy is widely used in plant cell imaging after the development of biological fluorescence labels in mid-1990s. However, fluorescence labeling itself affects the sample and the sample deviates from intact condition especially when labelling the entire cell. In this work, we report the dynamic images of Arabidopsis thaliana root cells. This demonstrates the multimodal nonlinear optical microscopy is an effective tool for long-term plant cell imaging.
Unlike those of other ordinary laser scanning microscopies in the past, nonlinear optical laser scanning microscopy (SHG, THG microscopy) applied ultrafast laser technology which has high peak powers with relatively inexpensive, low-average-power. It short pulse nature reduces the ionization damage in organic molecules. And it enables us to take bright label-free images. In this study, we measured cell division of zebrafish egg with ultrafast video images using multimodal nonlinear optical microscope. The result shows in-vivo cell division label-free imaging with sub-cellular resolution.
Nonlinear optical microcopy has become an important tool in investigating biomaterials due to its various advantages such as label-free imaging capabilities. In particular, it has been shown that third-harmonic generation (THG) signals can be produced at interfaces between an aqueous medium (e.g. cytoplasm, interstitial fluid) and a mineralized lipidic surface. In this work, we have demonstrated that label-free high-contrast THG images of the mycobacterium tuberculosis can be obtained using THG microscopy.
Nature of light is a fascinating subject of education and training for children. However, it is not easy to demonstrate and explain fundamental properties of the light to the primary & secondary school students. In this paper, we will present a new technique to teach concept of refraction, reflection, and total internal reflection of light in glasses by utilizing deviation angles of a prism for various surrounding index-matching oils.
We have investigated the intensity distribution through metallic nano double slit and nano double box by two dimensional finite-difference time-domain (FDTD) method based on Drude model. In particular, we find that there is an 'intermediate region' between near-field and far-field regions which varies with thickness and width of double slit. We will present the local fields propagating along and perpendicular to metal surface and their spatial distributions to verify the existence of the intermediate region.
Proc. SPIE. 7214, Ultrafast Phenomena in Semiconductors and Nanostructure Materials XIII
KEYWORDS: Ferroelectric materials, Quantum wells, Luminescence, Gallium arsenide, Single photon, Near field scanning optical microscopy, Near field, Tapered optical fibers, Temperature metrology, Absorption
We demonstrate an experimental setup combining the near-field scanning optical microscope (NSOM) and timecorrelated
single photon counting (TCSPC) system for high-resolution temporal and spatial spectroscopic measurements.
In particular, a multiple-quantum-well (MQW) structure was excited with a tapered optical fiber with 100 nm opening
aperture in near-field region and their temporal photoluminescence spectra were obtained by TCSPC system. We are
able to measure fluorescence decay time of a GaAs/AlGaAs MQW structure with well width of 75Å in the near-field
region at room temperature.
Field-induced Stark effects in Ag-coated CdS quantum dot structures are presented. We observe clear exciton peaks due to the quantum confinement effect and the surface plasmon effect in Ag-coated CdS quantum dot fabricated by gamma ray irradiation method. In addition, we observed also a dominant red-shift of the CdS exciton absorption peak as the Wannier Stark effect, implying the strong local field effect in the metal-coated semiconductor composite quantum dot system. The Stark shift of the exciton peak is investigated as a function of the local field for different silver thickness and various sizes of quantum dots based on the effective-mass Hamiltonian using the numerical-matrix-diagonalization method.
We calculate the bound-to-continuum transition amplitude in a biased GaAs/AlGaAs multiple quantum well structure. The continuum wave functions above the barrier bound on one side and free on the other extreme were normalized using the Dirac (delta) -function. The normalization renders that the amplitude of sinusoidal functions corresponding to different energies should be same in the far flat region. Calculated transition peak agrees well with the experimental results reported. Possibility of using complex energy representation to find the excited states is also discussed.
High speed single frame camera using proximity focused MCP was designed and manufactured by V TEK with help of Yonsei University. The gating time of this camera is adjusted by specially designed control board and S/W easily and this camera has high repetition rate up to 250 KHz. In this paper, we are introducing the newly designed Single Frame Camera and its applications.
The Prototype of Image Converter Streak Camera as single shot mode was developed by the joint research project between V TEK/Yonsei Univ. in Korea and GPI in Russia. The sweeping speed over (phi) 25 mm output screen area is selectable from 1 ns to 500 ns and the time resolution is better than 10 ps. This paper is showing the characteristics of streak camera and its simple applications.
As a part of the joint research projects between General Physics Institute and Yonsei University/V.TEK Company, an experimental prototype of an image converter camera is designed and manufactured. The camera operates both in single frame and single shot streak modes. Single frame exposures are varied in the 250 - 1000 ns range, while recording intervals in streak mode are adjusted within the 2 - 1000 ns range over a 25 mm-wide output screen area. Temporal resolution at maximum streak speed is better than 10 ps. Total camera gain is 5 (DOT) 104. The camera is equipped with a specially designed PIF-V.1 image converter tube. Available are choices among S1, S20, or S25 photocathodes fabricated onto Molibden glass/UV glass, or MgF2 substrate.