• Proceedings of the Korean Ceranic Society Conference
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• 2004.10a
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• pp.95.4-95.4
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• 2004

• Korean Journal of Optics and Photonics
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• v.15 no.1
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• pp.28-33
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• 2004

An in-line fiber coupler, based on side-polished single-mode fibers covered with an intermediate coupling layer and a planar waveguide, is analyzed by modeling the interaction region as an equivalent multi-layered planar waveguide. The reflectance for the multi-layered structure with and without buffer layer is illustrated as a function of the refractive index and thickness of the overlay waveguides. When the refractive index of the overlay waveguides is greater than that of the fiber core, the conditions for the intermediate coupling layer to increase the power coupling from the fiber to the overlays is also explained. Through the experimental results using a LiNbO$_3$planar waveguide, we show that the theoretical analysis is reasonable and in good agreement with the measured values.

• Electrical & Electronic Materials
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• v.9 no.3
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• pp.298-303
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• 1996

A double diffusion technique is developed to enhance the effective mode index of optical waveguides in $LiTaO_3$. It consists of Zn diffusion from the vapor phase at relatively low temperatures (750->$800^{\circ}C$), into waveguides initially produced by Ti indiffusion at higher temperature (1150->$1200^{\circ}C$). Both X- and Z-cut substrates are investigated. A model that combines profiles of both diffusion is formulated to calculate the expected effective index values for planar waveguides. Good agreement is found between experimental results and model predictions which assume that the initial Ti profile is not affected by the lower temperature Zn diffusion. Effective index enhancements as high as 0.005 and 0.003 are obtained by this method for the fundamental extraordinary and ordinary modes, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.390-390
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• 2008

In this paper, we have designed and fabricated optical waveguides based on the Mach-Zehnder Interferometer (MZI) for application to sensor. The evanecent-wave sensor based on the MZI principle has sufficiently high sensitivity to measure the change of the refractive index on surface of a waveguide. The waveguides 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 MZI optical waveguides was performed by a conventional Planar Lightwave Circuit (PLC) fabrication process. The fabricated MZI optical waveguide device was measured. According to the measurement result, the insertion loss of MZI optical waveguide device was below 3.5 dB and the polarization dependent loss (PDL) was within 0.1dB. In addition, we analyzed optical properties of MZI sensor according to the refractive index change of the sensor arm.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.1
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• pp.146-158
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• 1996

The WKB method has been widely used in evaluating of the propagation characteristics of planar waveguides with graded-index profiles. This method, however, yields large errors when a turning point is near or at the discontinuity in the presence of the index discontinuity or index slope discontinuity. Especially, in the case of a truncated-index profile, this phenomenon appears more clearly in the low-order modes and near the cutoff regions. The MWKB method is introduced to reduce these inherent errors of the conventional WKB method. The MWKB method is based on both the linearization of the index profile from an index discontinuity and the introduction of a virtual turning point. It is noticed that the b-v curves obtained by the MWKB method agree well with those of the finite-difference method, and that the phase shift at a turning point depends on both the index profile and its propagation constant. (author). refs., figs.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.11a
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• pp.37-39
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• 1994

We have investigated the characteristics of planar optical waveguides formed by silver ion-exchange. Experimental values of the effective indices of guided modes were obtained by measuring the synchronous angles of strongest coupling. Definition of an effective diffusion constant leads to the mode-dispersion curves applicable over a wide range of fabrication conditions. In order to compare experimental and theoretical results, We have plotted each mode index of a wide range of fabrication conditions.

• Proceedings of the Optical Society of Korea Conference
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• 1996.09a
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• pp.62-62
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• 1996

• Journal of electromagnetic engineering and science
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• v.11 no.2
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• pp.97-104
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• 2011

A planar slotted waveguide array antenna has been designed at 9.37 GHz for X-band radar applications. The antenna consists of multiple branchline waveguides with broadwall radiating shunt slots and a main waveguide to feed the branch waveguides through a series of inclined coupling slots. The antenna feed point is located at the center of the main waveguide. Element weights in the array have been calculated bysampling a continuous circular Taylor aperture distribution at the 25 dB sidelobe level in both the E and Hplanes. A commercially available electromagnetic (EM) simulation tool has been used to characterize the individual isolated slot and that data hassubsequently been used to design the planar array. The array is finally analyzed in a CST Microwave studio and the measured and simulated results have been found to be in good agreement.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.3
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• pp.343-351
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• 1988

Planar optical waveguides are fabricated on a Y-cut LiNbO3 single crystal substrate by Ti indiffusion method. From data measured by the bright M-line spectroscopy, refractive index profiles are reconstructed by WKB approximation method. Then, single strip, X-crossing strip, and Y-brinch strip optical waveguides are fabricated on X-cut LiNbO3 single crystal substrate, with waveguide patterns made by the laser beam direct writing method. And their near-field intensity profiles are observed after coupling the light to the waveguide edges.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.4
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• pp.297-301
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• 2000

Planar optical waveguides which have a higher refractive index than that of substrate were fabricated by proton exchange between $Li^+$ and $H^+$. Benzoic acid was used as proton source and process was carried out under the various reaction time and temperature. The depth of waveguide layer and the generated mode number were investigated by standard prism coupler. The cut-off depth for the fabrication of single mode optical waveguides was obtained by the function which was expressed on refractive index profile. Finally the experimental conditions for cut-of depth of single mode could be confirmed. Channel waveguides were manufactured from these confirmed conditions and the effective confinement of the induced light into waveguides was observed.