• Korean Journal of Optics and Photonics
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• v.24 no.2
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• pp.71-76
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• 2013

Using fluorescence correlation spectroscopy, we analyzed the change of effective focal volume of a confocal system with light intensity. The fluorescence correlation spectroscopy system was home-built in accordance with the He-Ne laser with a wavelength of 632.8 nm, and two kinds of samples (AlexaFluor657 and Quantum dot655) suitable for the wavelength of the laser beam were used. For each sample, we analyzed and compared the correlation functions obtained while changing the intensity of the light source in a range of 1~50 ${\mu}W$. The result shows that the radius of the focal area increases linearly through the increase of particle number and diffusion time in response to an intensity change in weak light below 10 ${\mu}W$. In the higher intensity region (>10~15 ${\mu}W$), the increasing rate of particle number and diffusion time keep increasing but at a much slower rate. Through this result, it was also found that the radius increasing rate of the focal area was reduced however, the radius still increased slightly.

• Korean Journal of Optics and Photonics
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• v.3 no.3
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• pp.183-190
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• 1992

Luminescence properties of asymmetric double quantum well structure composed of $Al_x/Ga_{1-x}$ /As AIAs/GaAs have been studied by steady state and time-resolved photoluminescence and phtoluminescence excitation spectroscopy at low temperature. Two quantum well samples with different barrier thickness (15$\AA$ and 150$\AA$) were prepared to investigate the dependence of tunneling characteristics on barrier thickness. The abscence of excitonic recombination peak from $Al_x/Ga_{1-x}$As well for the 15$\AA$ barrier sample indicates a very fast electron tunneling to GaAs well. Meanwhile, T-X transition between well and barrier is supposed to be a major route for the fast decay of luminescence from $Al_x/Ga_{1-x}$As well in the 150$\AA$ barrier sample. Time-resolved photduminescence from GaAs well of 15$\AA$ sample shows the exsitence of the rise with 100 ps which is attributed to the hole tunneling.

• Current Optics and Photonics
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• v.6 no.5
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• pp.497-505
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• 2022

Topological photonic nanocavities are considered to possess outstanding optical performance, and provide new platforms for realizing strong interaction between light and matter, due to their robustness to impurities and defects. Here hybrid plasmonic topological photonic nanocavities are proposed, by embedding various plasmon nanoantennas such as gold nanospheres, cylinders, and rectangles in a topological photonic crystal corner-state nanocavity. The maximum quality factor Q and minimum effective mode volume V_eff of these hybrid nanocavities can reach the order of 10⁴ and 10^-4 (𝜆/n)³ respectively, and the high figures of merit Q/V_eff for all of these hybrid nanocavites are stable and on the order of 10⁵ (𝜆/n)^-3. The relative positions of the plasmon nanoantennas will influence the coupling strength between the plasmon structures and the topological nanocavity. The hybrid nanocavity with gold nanospheres possesses much higher Q, but relatively large V_eff. The presence of a gold rectangular structure can confine more electromagnetic energy within a smaller space, since its V_eff is smallest, although Q is lowest among these structures. This work provides an outstanding platform for cavity quantum electrodynamics and has a wide range of applications in topological quantum light sources, such as single-photon sources and nanolasers.

• Korean Journal of Optics and Photonics
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• v.35 no.4
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• pp.135-142
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• 2024

Biomedical imaging technologies refer to imaging techniques used in biological research and medical technology that are essential for exploring biological processes, structures, and conditions. They also play a crucial role in the early diagnosis of diseases and the development of treatments. Optical imaging technologies, in particular, are the most widely used and actively researched in biological studies. The major obstacles to technological advancement are the limitations in resolution and light penetration depth. Recently, many technologies have been studied to overcome these limitations using metamaterials. These are materials that can freely manipulate the properties of light through the regular arrangement of nanostructures and have established themselves as innovative tools in the imaging field. This article aims to provide a detailed introduction to the working principles and key applications of these technologies.

• Korean Journal of Optics and Photonics
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• v.11 no.6
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• pp.441-446
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• 2000

Wigner functions and density matrices are computer simulated for various quantum mechanical states of light. Wigner function and density matrices are evaluated by filtered back projection which includes inverse Radon transform from the distribution function of the photocurrents, which are calculated in the balanced homodyne detection scheme. The density matrix is also directly obtained by using the pattern function from the simulated phase independent photocurrent distribution function. ction.

• Korean Journal of Optics and Photonics
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• v.7 no.3
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• pp.272-279
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• 1996

A simple transfer matrix algorithm to analyze the properties of 2 dimensional waveguides is introduced. We applied this algorithm to strained InGaAs/InGaAsP GINSCH MQW laser structures. We studied how optical confinement factor and effective refractive index, which are important in calculating the modal gain, depend on the structure parameters such as waveguide width, shape of GRIN, and number of quantum wells. Especially we suggested that the concept of effective waveguide width is very useful in understanding the GRINSCH waveguide.

• Korean Journal of Optics and Photonics
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• v.8 no.4
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• pp.353-355
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• 1997

A single molecule detection system, which consists of confocal fluorescence microscope and single photon counter, has been used to observe the dye concentration dependence of photon counting rate. With increasing concentration, a saturation effect of counting is observed and demonstrated on the basis of the dead time of photon detector. The equations presented here show the relations between the counting rate and some parameters such as probe volume, quantum efficiency of detector, and fluorescence photon number entered onto detector. The signal-to-noise ratio is also discussed briefly.

• Proceedings of the Korean Vacuum Society Conference
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• 2007.02a
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• pp.104-104
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• 2007

• Proceedings of the Korean Vacuum Society Conference
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• 2009.08a
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• pp.165-165
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• 2009

• Proceedings of the Korean Vacuum Society Conference
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• 2009.08a
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• pp.162-162
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• 2009