• Proceedings of the Optical Society of Korea Conference
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• 2004.07a
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• pp.256-257
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• 2004

• Proceedings of the Optical Society of Korea Conference
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• 2007.02a
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• pp.285-286
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• 2007

• Proceedings of the Optical Society of Korea Conference
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• 2006.02a
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• pp.321-322
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• 2006

• Korean Journal of Optics and Photonics
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• v.16 no.4
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• pp.376-383
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• 2005

We designed and fabricated integrated-optic tunable polarization controllers based on $LiNbO_3$ with the Ti-indiffused waveguide along the y-axis utilizing the electro-optic effect. The device consists of $TE↔TM$ mode converters and TE/TM phase shifters. We analyzed the operation principles of each device utilizing transfer matrices based on a Jones matrix and simulated shifting of the center wavelength by inducing voltage. We confirmed experimentally that the fabricated devices control the tunability of the center wavelength and the input SOP.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.3
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• pp.124-127
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• 2005

It is demonstrated that the annealing process for Ti in-diffusion to z-cut $LiNbO_3$ at temperature lower than the curie temperature in a platinum (Pt) box can cause a ferroelectric micro-domain inversion at the +z surface and Li out-diffusion, therefore which should be avoided or suppressed for waveguide type periodically poled lithium niobate (PPLN) devices. The depth of the inversion layer depends on the Ti-diffusion conditions such as temperature, atmosphere, the sealing method of $LiNbO_3$ in the Pt box and crystal orientation is experimentally examined. The result shows that the polarization-inverted domain boundary appears at the only +z surface and its thickness is about $1.6{\mu}m$. Also, for the etched $LiNbO_3$, surface the domain shape was observed by the optical microscope and atomic force microscopy (AEM), and distribution of the cation concentrations in the $LiNbO_3$ crystal by the secondary ion mass spectrometry (SIMS).

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.5
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• pp.69-79
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• 1999

In this paper, we proposed a diffuion model of Ti diffused lithium niobate optical waveguide for fabricating waveguides with high refractive index and compared with conventional one. The achivement of low optical insertion loss between waveguide interface and single mode fibers was discussed as a function of Ti thickness for $\lambda$=1.55$\mu\textrm{m}$ The proposed diffusion method exhibited higher refractive index waveguide than conventional one for $\lambda$=0.6328$\mu\textrm{m}$ We have achieved the total fiber-waveguide-fiber insertion loss as low as 0.5dB/cm in z-cut and 1$\pm$0.5dB/cm in x-cut for both TM and TE mode of Mach-Zehnder interferometric waveguide in the range of Ti thickness 1000-1400$\AA$ for $\lambda$=1.55$\mu\textrm{m}$ From these results, this diffusion model for making a low loss waveguide can be used for low-power-modulators and switches.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.4
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• pp.371-378
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• 1992

In this paper we report the fabrication of a planar optical wavehuide lens on a Y-cut LiNbO3 substrate by Ti_indiffusion and Ti-indiffused proton-exchange(TIPE). LiNbo3 planar waveguides are fabricated and refractive indices of the waveguides are fabricated and refractive indices of the waveguides are measured. Based on the measured indices, palanr waveguide lenses are designed and fabricated. The measured focal point and spot size of the fabricated lens are in good agreement with those of the designed lens.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.6
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• pp.61-70
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• 1999

An optical switch composed of three-identical, equally-spaced $Ti:LinbO_3$ waveguides and overlaid Al electrodes of CPW structure was designed and fabricated. Patterned Ti was diffused into z-cut $LinbO_3$ substrates at $1025^{\circ}C$ for 6 hours to make a three-waveguide directional coupler. $SiO_2$ buffer layer of $1.2{\mu}m$ was grown by the PECVD to reduce the propagation loss of TM mode, and Al electrodes were built on the layer for switching the guided beam. For an incident beam of ${\lambda}=1.3{\mu}m$, almost perfect optical coupling between two outer waveguides was observed. When an electric field was applied to detune the three waveguides anti-symmetrically, the optical switching phenomenon was successfully confirmed.

• Journal of the Optical Society of Korea
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• v.7 no.4
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• pp.253-257
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• 2003

We propose and demonstrate a novel polarization- and wavelength-independent digital electrooptic switch in $Ti:LiNbO_3$ with switching voltage of ${\pm}$32V at $1.55{\mu}m$ wavelength. This $2{\times}2$ integrated optic switch is characterized by a step-like response to the applied voltage. Switching is achieved through adiabatic mode evolution in an asymmetric waveguide junction. An average insertion loss of ∼4.5dB and polarization independent switching with average crosstalk of -12dB are achieved.

• Korean Journal of Optics and Photonics
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• v.15 no.5
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• pp.475-482
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• 2004

We have fabricated a LiNbO$_3$ travelling-wave optical modulator. The travelling-wave modulator consisted of M-Z(Mach-Zehnder) interferometer and CPW(Coplanar Waveguide) travelling-wave electrodes. Design of CPW electrodes were performed by SOR(Successive Over Relaxation) to obtain the conditions of Microwave effective index and impedance matching. The fabricated modulator had -3.2 dB insertion loss, and S$_{11}$ below -15 dB up to 12 GHz, S$_{21}$ better than -3 dB upto 7 GHz. It turned out that the optical response showed the 3 dB bandwidth of above 12 GHz.