• Korean Journal of Optics and Photonics
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• v.26 no.6
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• pp.318-321
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• 2015

We demonstrate a frequency-resolved optical grating (FROG) device for measuring the intensity and phase versus time of several-tens-of-picoseconds laser pulses, using a thick nonlinear optical crystal. The huge pulse-front tilt generated by a holographic grating increases the temporal range of the device, which can make a single-shot measurement of laser pulses less than 100 ps in duration. To verify the measurement technique, we generate double pulses using a Michelson interferometer. The measured duration of a single pulse is about 300 fs and the measured maximum delay of two pulses is 60 ps, which implies that the proposed FROG device can measure laser pulses with maximum pulse width of about 120 ps.

• Korean Journal of Optics and Photonics
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• v.4 no.4
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• pp.397-402
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• 1993

This paper presents a new computational algorithm of phase-shifting interferometry which can effectively eliminate the uncertainty errors of the reference phases encountered in obtaining multiple interferograms. The algorithm treats the reference phases as additional unknowns and determines their exact values by analyzing interferograms using numerical least square technique. A series of simulations prove that this algorithm can improve measuring accuracy being unaffected by the nonlinear and random errors of phase-shifters.

• Korean Journal of Optics and Photonics
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• v.4 no.4
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• pp.457-463
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• 1993

We investigated that the CARS signals generated from resonant or nonresonant contributions can be selectively suppressed by phase-controlled nonlinear interferometry. To control the phase of the CARS signal over a broad spectral range, a home-made phase shifting unit was used, whose thickness was automatically controlled as the wavelength of Stokes beam scaned. Using this technique, we recovered the Q-branch resonance lines of carbon monoxide and HC1 which had been distorted and buried by the nonresonant and resonant signal of propane respectively. All the spectrum measured have been normalized by reference signal which had no resonance lines over the spectral range of interest.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.986-989
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• 2007

In this review, several aspects for improving the quality of materials parameters of Nematic Liquid Crystals (NLCs) and Ferroelectric Liquid Crystals (FLCs) will be discussed. In particular the decrease of the response time is a need. It will be demonstrated that the materials parameters of NLCs and FLCs can be improved among other ways due to optimization of chemical structures of the NLCs and /or FLCs mixtures, due to doping them with nanomaterials and by using fast elastic relaxation processes.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.10-11
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• 2006

The azobenzene dendrimer is one of the dendrimeric macromolecules that include the azo-group exhibiting a photochromic character. Due to the presence of the charge transfer element of the azo-group and its rod-shaped structure, these compounds are expected to have potential interest in electronics and photoelectronics, especially in nonlinear optics. In the present paper, we give pressure stimulation to organic thin films and detect the induced displacement current. Functional photoisometrization organic molecular the photo-stimulus to organic monomolecular L films and LB films of dendrimer and SASH were performed. The SASH organic monolayer in case of pressure stimulus occurred that positive course but in case of the photo-stimulus compared positive and negative. It is assumed that generation forms of displacement current were measured when photo-stimulus for impression.

• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.124-125
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• 2000

Since Nye and Berry$^{(1)}$ showed that in free space the electromagnetic field could contain stable, propagating phase singularities termed "dislocations", optical dislocations have been extensively investigated in nonlinear optics and laser physics. As the wave propagates, the lines of constant phase surrounding a dislocation trace out a spiral in space or in time. So these phase singularities are now usually referred to as optical vortices. Baranova and her co-workers$^{(2)}$ have shown that in fully developed speckle patterns, there is, one optical vortex accompanying each speckle spot on average. Among these vortices there are networks in phasemap because only one phase is to be assigned in one point except optical dislocations having zero amplitude. Freund et al.$^{(3)}$ have been studied optical dislocation networks and simulations are compared with experimental results. (omitted)

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.4
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• pp.153-156
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• 2003

Pure and Ethylenediaminetetraacetic acid (EDTA) doped L-arginine phosphate (LAP) single crystals were grown from the aqueous solution by temperature lowering method. The effect of EDTA additive on the solubility and metastable zone width of LAP solution has been investigated. Addition of EDTA has enhanced the metastable zone width of LAP and hence bulk crystals could be grown. The growth rate along the [100] direction increases with EDTA additive. Powder X-ray diffraction and FTIR studies reveal the absence of EDTA in the lattice of LAP, This reveals that the addition of EDTA to LAP doesn't influence the crystallinity. However, the transmittance and NLO properties significantly increase with EDTA additive and hence bulk LAP crystals are useful for laser fusion experiments.

• Korean Journal of Optics and Photonics
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• v.4 no.1
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• pp.66-72
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• 1993

Additive-pulse mode-locking (APM) was performed in a $1.053{\mu}m$ cw Nd:YLF laser by coupling a nonlinear external external cavity to the main cavity. The APM pulsewidth was 4.5 ps and the average output power was 1.5 W. This APM pulse was compressed by an optical fiber and a grating pair to be as short as 210 fs with a peak power of 17 kW.

• Journal of the Korean Ceramic Society
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• v.47 no.5
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• pp.430-432
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• 2010

We verified through a noncritical phase-matched second-harmonic generation experiment that the periodically-poled $LiNbO_3$ (PPLN) had a large effective nonlinear optical coefficient, demonstrating that the QPM grating was uniform throughout the entire length of PPLN. The quasi-phase matching temperature was $193.4^{\circ}C$. The maximum SHG output power at the fundamental power of 2.0 W was found to be 18.0 mW; generated second-harmonic beam was found to have no photorefractive effect.

• Korean Journal of Optics and Photonics
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• v.11 no.3
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• pp.187-192
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• 2000

We analyze the parametric amplification by the nonlinear characteristics in a semiconductor laser using a perturbation theory and discuss its result. The parametric gain increases with increase of the pump modulation current. It is due to shift of the resonance frequency as the pump modulation current increases. However, it decreases with increase of the bias current and damping constant. Also, it needs phase matching between the pump modulation current and signal modulation current to maximize the parametric gain. The gain decreases for a large signal modulation current due to the saturation of the amplified power. power.