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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Korean Journal of Optics and Photonics
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Journal DOI :
Optical Society of Korea
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Volume & Issues
Volume 16, Issue 6 - Dec 2005
Volume 16, Issue 5 - Oct 2005
Volume 16, Issue 4 - Aug 2005
Volume 16, Issue 3 - Jun 2005
Volume 16, Issue 2 - Feb 2005
Volume 16, Issue 1 - Feb 2005
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Ghost Imaging With Classically Correlated Beams
Bae, Sam-Yong ; Youn, Sun-Hyun ;
Korean Journal of Optics and Photonics, volume 16, issue 6, 2005, Pages 481~484
DOI : 10.3807/KJOP.2005.16.6.481
Quantum ghost imaging uses quantum mechanically entangled photons to form an image of an object. The quantum ghost image is also obtained by means of classical coincidence measurements with a classically correlated light source[1,2]. In this work we performed classical coincidence imaging experiments with classically correlated beams in their direction of propagation. We observed the ghost interference patterns which were usually made by quantum mechanically entangled states and we also analyze in detail the mechanism of the ghost imaging with classically correlated lights. We made? the classically correlated source with an Ar laser and controlled the direction of the light by a mirror? mounted on a small speaker.
Suppression of Stimulated Brillouin Scattering in Optical Fiber using Sampled-Fiber Brags Grating
Lee, Ho-Joon ;
Korean Journal of Optics and Photonics, volume 16, issue 6, 2005, Pages 485~489
DOI : 10.3807/KJOP.2005.16.6.485
I have investigated a scheme for suppressing stimulated Brillouin scattering in optical fibers. The scheme makes use of a sampled Bragg grating fabricated within the fiber used for transmitting intense Q-switched pulses. The grating is designed such that the spectrum of the Stokes pulse generated through stimulated Brillouin scattering falls entirely within its stop band. I show numerically that the number of sampled fiber Bragg gratings in 1 m is applied directly to suppressing stimulated Brillouin scattering rather than the coupling coefficient. This prevents the build up of the backward-propagating Stokes wave and mitigates the deleterious effects of stimulated Brillouin scattering. The simulation shows that 15 ns pulses with 1 kW peak power can be transmitted though a 1 m-long fiber with little energy loss using this scheme.
Characterization of Supercontinuum Generation as a function of Pump Wavelength and Intensity in Photonic Crystal Fiber
Kim, Jong-Doo ; Yee, Ki-Ju ; Jeon, Min-Yong ; Ahn, Seong-Joon ; Choi, Yong-Gyu ;
Korean Journal of Optics and Photonics, volume 16, issue 6, 2005, Pages 490~493
DOI : 10.3807/KJOP.2005.16.6.490
We have experimentally studied supercontinuum generation in a photonic crystal fiber as a function of pump wavelength and intensity with 100 fs pulsewidth. A supercontinuum over 750 nm spectral width with amplitude variation less than 10 dB has been achieved. It was generated by coupling femtosecond pulses from a mode-locked Ti:Sapphire laser into a 2 m long photonic crystal fiber. Adjusting the parameters of the pump source, it was also possible to control different spectral features of the supercontinuum radiation.
A Short Wavelength Filter Based on Dissimilar Dispersive Property Between a Thermally Expanded Cored Fiber and an External Medium
Kim, Kwang-Taek ; Lee, Kyu-Hyo ; Shin, Eun-Soo ; Hwangbo, Seung ; Sohn, Kyung-Rak ; Kim, Jeong-Geun ; Lee, Dong-Ho ; Song, Jae-Won ;
Korean Journal of Optics and Photonics, volume 16, issue 6, 2005, Pages 494~499
DOI : 10.3807/KJOP.2005.16.6.494
We have demonstrated a fiber short-wavelength filter with a good cut-off property using dissimilar dispersive properties between? a thermally expanded cored fiber and an external medium. Side-polishing is applied to coupling between the fiber and the external medium. The experimental results revealed that the bend edge wavelength can be adjusted by controlling the degree of core expansion. Futhermore, the sharpness of wavelength response? was significantly? improved by employing expanded core fiber instead of a conventional single mode fiber. Tuning range of the band edge wavelength exceeded 400 m based on thermo-optic effect of the external medium.
Improvement of Two-Dimensional Terahertz Image by Digital Image Processing
Shon, Chae-Hwa ; Jin, Yun-Sik ; Jeon, Seuk-Gy ; Kim, Keun-Ju ; Jung, Sun-Shin ; Yong, Chong-Won ;
Korean Journal of Optics and Photonics, volume 16, issue 6, 2005, Pages 500~507
DOI : 10.3807/KJOP.2005.16.6.500
Two-dimensional (2D) images that are produced by terahertz (THz) irradiation we presented. It is possible to obtain 2D image of various materials by observing the amplitude and the phase of the THz signals which go through them. Better images are produced by combining the amplitude and phase of the signal rather than using only one of these. Homomorphic filtering that is one elf the well-known technique of digital image signal processing is effective to reduce the noise signal and can provide better quality images. The results can be applied to real-time imaging afterwards.
Generation of Lens surface by moving mask lithography
Lee Joon-Sub ; Park Woo-Jae ; Song Seok-Ho ; Oh Cha-Hwan ; Kim Pill-Soo ;
Korean Journal of Optics and Photonics, volume 16, issue 6, 2005, Pages 508~515
DOI : 10.3807/KJOP.2005.16.6.508
We propose a fabrication method for refractive lens by variable velocity moving mask lithography and slit pattern. Distribution of exposure dose should be controlled for the curved photoresist surface that works as a refractive surface. We analyze theoretically the distribution of exposure dose by change of moving velocity, moving direction of mask and the shape of mask pattern, and confirm for the curved surface experimentally. The lens could have sag height of a few of hundreds
, by using thick photoresist or Deep RIE process.
Phase-Shifting System Using Zero-Crossing Detection for use in Fiber-Optic ESPI
Park, Hyoung-Jun ; Song, Min-Ho ; Lee, Jun-Ho ;
Korean Journal of Optics and Photonics, volume 16, issue 6, 2005, Pages 516~520
DOI : 10.3807/KJOP.2005.16.6.516
We proposed an efficient phase stepping method for the use in fiber-optic ESPI. To improve phase-stepping accuracy and efficiency, a fiber-optic Michelson interferometer was phase-modulated by a ramp-driven fiber stretcher, resulting in 4
phase excursion in the PD interference signal. The zero-crossing points of the signal, which have consecutive
phase difference, were carefully detected and used to generate trigger signals for the CCD camera. From the experimental results by using this algorithm,
/2 phase-stepping errors between the speckle patterns were measured to be less than 0.6 mrad with 100 Hz image capture speed. Also it has been shown that the error from the nonlinear phase modulation and environmental perturbations could be minimized without any feedback algorithm.
Assembly of diameter 300 mm optical beam director
Yang, Ho-Soon ; Lee, Yun-Woo ; Kim, Jeong-Ju ; Eum, Hae-Dong ; Lee, Soo-Sang ; Kim, Yeon-Soo ; Kim, Hyun-Sook ;
Korean Journal of Optics and Photonics, volume 16, issue 6, 2005, Pages 521~526
DOI : 10.3807/KJOP.2005.16.6.521
We assembled the optical beam director with diameter 300 mm. This consists of primary, secondary mirrors and 5 folding mirrors. Among them, the primary mirror is the most important component so that we measure any possible deformation on it at every step of assembly. Also, we developed the systematic alignment algorithm, which is essential because the number of mirrors is 7. The final wavefront error of the system is 1.9 wave rms (wave
Analysis of Self-Pulsation Characteristics in Multi-Section Complex-Coupled DFB Lasers With Amplifying Optical Feedback
Kim, Sang-Taek ; Kim, Tae-Young ; Kim, Boo-Gyoun ; Leem, Young-Ahn ; Park, Kyung-Hyun ;
Korean Journal of Optics and Photonics, volume 16, issue 6, 2005, Pages 527~534
DOI : 10.3807/KJOP.2005.16.6.527
We investigate the pulsation characteristics in a multi-section DFB laser which is composed of one DFB section, phase tuning section, and gain section. Multi-section DFB lasers with anti-phase (AP) complex-coupled (CC) DFB structure show wide current ranges of gain and phase tuning sections fer stable pulsations compared to those with in-phase CC DFB structure or index-coupled DFB structure. For multi-section DFB lasers with AP CC DFB structure, the current range of a gain section for stable pulsations increases and the tuning range of the pulsation frequency increases as a coupling strength or a gain coupling coefficient increases Also, the tuning range using the phase variation in a phase tuning section increases. For a fixed coupling strength, the current ranges of gain and phase tuning sections for stable pulsations increase and the tuning range of the pulsation frequency increases as the length of a DFB section increases.
Generation of Femtosecond Pulses in a Passively Mode-Locked 100 MHz Cr
Cho, Won-Bae ; Rotermund Fabian ; Kim, Jong-Doo ; Jeon, Min-Yong ; Suh, Ho-Suhng ;
Korean Journal of Optics and Photonics, volume 16, issue 6, 2005, Pages 535~541
DOI : 10.3807/KJOP.2005.16.6.535
We report on the development of a passively mode-locked near-infrared femtosecond laser with Cr:YAG crystal that operates near room temperature. The laser wavelength could easily be tuned by using only the internal prism pair over 110 nm from 1400 nm to 1510 nm in cw and over about 30 nm in mode-locked operation, respectively Maximum cw output powers of 810 mW were obtained with
output coupler for absorbed pump powers of 7.6 W. For compensation of the internal group velocity dispersion, an IR graded prism pair was used. The Cr:YAG laser delivered nearly Fourier-transform limited pulses with a pulse duration as short as 64 fs at 100 MHz repetition rate. In the mode-locked regime, the laser was operating at 1510 nm with a spectral bandwidth of 44 nm. In order to avoid unstable mode-locking and power instabilities, self-built tubes were inserted into the beam path in the resonator and purged with N2 gas. Finally, output powers of the Cr:YAG laser were optimized to 250 mW fer long time stable mode-locked operation.
Compensations of Polarization Mode Dispersion and Thermal Drift in Optical Coherence Tomography with PZT Optical Delay Lines
Kim, Young-Kwan ; Park, Sung-Jin ; Kim, Yong-Pyung ;
Korean Journal of Optics and Photonics, volume 16, issue 6, 2005, Pages 547~552
DOI : 10.3807/KJOP.2005.16.6.547
We have fabricated and characterized optical delay lines for optical coherence tomography, which is composed of cylindrical PZT(piezoelectric transducer) and single mode optical fiber. The polarization mode dispersion from the optical delay lines was compensated by the polarization controllers. By applying the duplex optical delay line, we minimized the thermal drift due to optical delay lines and obtained the scan range of 2 times that of a single optical delay line. The OCT system showed resolution of
, scanning range of 1.68mm, and scanning speed of 360.4mm/s.
Pulsed Terahertz Emission and Detection Properties from ZnTe Crystal
Jin, Yun-Sik ; Jeon, Seuk-Gy ; Kim, Keun-Ju ; Sohn, Chae-Hwa ; Jung, Sun-Shin ;
Korean Journal of Optics and Photonics, volume 16, issue 6, 2005, Pages 553~559
DOI : 10.3807/KJOP.2005.16.6.553
Pulsed terahertz (THz) radiation was generated by optical rectification and detected by a fee space electro-optic sampling (FS-EOS) method. We used ZnTe (110) crystals for both generation and detection. By coating dielectric anti-reflection film on the ZnTe crystal surface, we can reduce the reflectance of a pump laser beam from
, and the terahertz pulse amplitude increased
compared with an uncoated crystal. A wider bandwidth of THz radiation was obtained by using a thinner crystal but the signal intensity was decreased in this case. And variations of THz radiation by changing orientation of the ZnTe crystal with respect to the pump (or probe) laser polarization, and by changing the power of the pump laser have also been investigated and discussed.
Polarized Light Scattering Spectroscopy for Particle Size Measurement on Surface
Cho, Hyoung-Jun ; Choi, Chi-Kyu ; Kim, Doo-Chol ; Yu, Young-Hun ;
Korean Journal of Optics and Photonics, volume 16, issue 6, 2005, Pages 560~564
DOI : 10.3807/KJOP.2005.16.6.560
We used the polarized light scattering spectroscopy(PLSS) to get selectively the particle size information on a surface in optically diffuse material, and we analyzed the experimental results by Mie scattering theory. We found that the PLSS was the proper method fer getting the surface information in optically diffuse material. This method is able to be used in biotechlology area for diagnostics.