• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.995-997
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• 1998

The experimental optical cross-connect based on delivery and coupling switch features all-optical property. It consists of erbium-doped fiber amplifiers, arrayedwaveguide gratings, optical switches and optical combiners. In 4 channel wavelength division multiplexing with 1.6 nm spacing, the difference in power level among channels for output signals from the optical cross-connect was within 2 dB.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.386-386
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• 2006

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.223-223
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• 2009

In this paper, designed and simulated Power Splitter (PS) integrated Mach-Zehnder interferometer (MZI) based planar type optical waveguide devices (which is called here a PS-MZI). The PS-MZI optical waveguide sensor was preceded by a Y-junction, which splits the input power between the sensor, and a reference branch, to minimize the effect of optical power variations. The PS-MZI optical waveguide sensor induced changing phases of the incident beam, which had fallen upon the waveguide through computer simulation, according to the small changes in the index of refraction, thus beam intensity was changed. The waveguide were optimized at a wavelength of 1550 nm and fabricated according to the design rule of 0.45 delta%, which is the difference of refractive index between the core and clad. The fabrication of PS-MZI optical waveguide sensor was performed by a conventional planar lightwave circuit (PLC) fabrication process. The PS-MZI optical waveguide that was fabricated to be applied as a biosensor revealed a low insertion loss and a low polarization-dependent loss. After having etched the over-clad at the sensor part in the MZI optical waveguide that was fabricated, Ti deposition was made on the adhesion layer, and then Au thin-film deposition was carried out thereon. In addition, its optical properties were measured by having changed the index of refraction oil at the sensing part of the MZI. To apply the planar type PS-MZI optical waveguide as a biosensor, a detection test for Staphylococcus aureus was conducted according to changes in concentration, having adopted Ti-alkoxide as ligand. The detection result of the S. aureus by the PS-MZI optical waveguide sensor was possible to the level of $10^1$ CFU/ml.

• Journal of the Optical Society of Korea
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• v.16 no.2
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• pp.95-100
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• 2012

We show that the minimum EOP (eye-opening penalty) obtained by tunable dispersion compensation is a function of a figure of merit for a nonlinear process, $I_0L_{eff}$, where $I_0$ is the optical intensity and $L_{eff}$ is the effective length of the interaction region. Using this rule, we do not need to conduct nonlinear simulations in all the cases of signal power and transmission length to obtain the signal distortion in dispersion-managed optical transmission. Instead, we need to conduct a simulation in only one case of a signal power and find the functional relation, and then we can obtain the values of the signal distortion in other cases using the discovered functional relation. This technique can reduce the number of nonlinear simulations to less than 10%.

• Current Optics and Photonics
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• v.7 no.1
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• pp.28-32
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• 2023

Frequency characteristics of gain-saturated erbium-doped fiber amplifier (EDFA) are experimentally evaluated to mitigate the optical signal fluctuation induced by atmospheric turbulence in terrestrial freespace optical communication systems. Here, an acousto-optic modulator (AOM) is used to emulate optical signal fluctuations induced by atmospheric turbulence. The waveform which is generated in proportion to the refractive-index structural parameters is used to drive the AOM at various periodic frequencies. Thus, the dependence of the signal fluctuation suppression on the frequency is evaluated. The experiment is conducted using a periodic frequency sweep of the AOM driving voltage waveform and signal input power variation of the amplifier. It is observed that a low periodic frequency and high input signal power effectively suppress the optical signal fluctuation. This study evaluates the experimental results from the high-pass filter and gain-saturation characteristics of the EDFA.

• Korean Journal of Optics and Photonics
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• v.7 no.2
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• pp.136-141
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• 1996

We present a novel description of TE nonlinear guided waves in planar waveguides with two nonlinear bounding thin films. The nonlinear dispersion relations of the nonlinear waveguides are obtained by adopting the nonlinear transfer matrix. The optical properties obtained from these equations include: the power dependence of mode indices, the transition of the field maximum location, and the power distribution. The planar waveguide with self-focusing nonlinear layers shows the optical bistability of power-dependent mode indices, and the critical powers for the optical bistability increase with decreasing thickness of the nonlinear layers. The power distributions display the optical bistabilities, similar to those of nonlinear Fabry-Perot etalon.

• Korean Journal of Optics and Photonics
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• v.8 no.6
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• pp.492-499
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• 1997

We proposed and studied an all-optical switching device made of a bent nonlinear waveguide and an all-optical logic gate made of a bent nonlinear Y-junction. The proposed devices as switch and a logic function are based on the evolution of nonlinear guided wave along a bent nonlinear waveguide. Since the characteristics of beam propagation depens on the nonlinearity, input power and bent angle of waveguide, the characteristics of output power transmission is calculated by variation the such parameters. Furthermore, by calculating the output power through the nonlinear media with different positions of detector in nonlinear media, we could find the ideal digital switching performance at specific position of detector and implement several all-optical logic functions (AND, OR, XOR) by power contrast between waveguide end and nonlinear media.

• Korean Journal of Optics and Photonics
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• v.17 no.2
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• pp.120-126
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• 2006

A grating-assisted fiber coupler(GAFC), which consists of a thin-film waveguide with grating and circular optical fiber, is proposed and the optimized power coupling is evaluated by using a technique amenable to rigorous longitudinal modal transmission-line theory(L-MTLT). In addition, novel criteria to couple an optical signal incident through the grating waveguide to a single-mode optical fiber are proposed. The numerical result reveals that the optimized power coupling occurs at minimum-gap condition between rigorous modes rather than for the conventional phase-matching condition.

• Journal of the Optical Society of Korea
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• v.17 no.1
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• pp.33-37
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• 2013

In this study a new design concept of the Fabry-Perot filter, constructed with an anisotropic space layer and a couple of isotropic mirrors, was proposed based on the Maxwell equations and the characteristic matrix method. The single- and double-cavity Fabry-Perot filters were designed, and their optical properties were investigated with a developed software package. In addition, the dependence of the transmittance and phase shift for two orthogonal polarization states on the column angle of the anisotropic space layer and the incidence angle were discussed. We demonstrated that the polarization state of electromagnetic waves and phase shifts can be modulated by exploiting an anisotropic space layer in a polarization F-P filter. Birefringence of the anisotropic space layer provided a sophisticated phase modulation with varied incidence angles over a broad range, resulting in a wide-angle phase shift. This new concept would be useful for designing optical components with isotropic and anisotropic materials.

• Korean Journal of Optics and Photonics
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• v.13 no.6
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• pp.479-485
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• 2002

We propose a vector analysis for designing multimode-interference power splitters, which can show an arbitrary splitting ratio. Power splitting is a fundamental characteristic in integrated optical circuits and its value would be multiplied for many applications if the splitting ratio could be selected freely. Since the vector analysis utilizes a graphical method based on the previously-reported mathematical results of multimode interference, it shows an excellent advantage especially for designing power splitters with an arbitrary splitting ratio.