• Proceedings of the Optical Society of Korea Conference
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• 2006.02a
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• pp.137-138
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• 2006

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.9
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• pp.93-99
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• 1998

A novel four-channel narrowband wavelength demultiplexer using integrated four vertical directional coupler structures is proposed and theoretically investigated. Four ridge waveguide with different ridge width are vertically coupled to a strip-loaded waveguide which results four different wavelengths filtered out to each ridge waveguide. In order to reduce the side-lobes, the coupling coefficients are varied along the propagation direction. The spectral responses of channels were found to be quite uniform. An average channel spacing of 7 nm with power coupling efficiency of ~90%, 3-dB passband width of 2 nm, and 20 dB side-lobe suppression ratio was achieved.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.5
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• pp.9-14
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• 2004

Lightwave communication system for Wavelength division multiplexing(WDM) consists of multiplexer, demultiplexer and optical Inter. But, the existing multiplexer, demultiplexer and optical filter is difficult to minimize system and reduce weight because they are not integrated device type. In this paper, thus, we propose the OADM baed on a Mach-Zehnder interferometer(MZI) with FBG(fiber Bragg Slating) in the interferometer Ems. The OADM using FBG. and MZI is able to minimize system and reduce weight. We analyze output characteristics of OADM and present the optimum design data through the computer simulation and experimentation. Also unposed OADM fits for DWDM(Dense WDM) system because of wide bandwidth by tuning narrow linewidth.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.6
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• pp.79-86
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• 1999

We propose a new photorefractive demultiplexer(DMUX) for WDM communicaytion system using a wavelength selectivity and demultiplexing properties of a volume holographic grating filters formed in $LinbO_3$ crystal doped with 0.015wt.% Fe. The wavelength selectivity properties of the filter are analyzed and experimentally investigated as a function of the following parameters : the crossing angle of the two writing beams, the reading-beam angle and writing-beam size. In addition, applying these wavelength selectivity properties and the multiplexing technique for recording multiple-exposure filters with equal diffraction efficiency, some preliminary experimental results are presented for use as DMUX.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.1A
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• pp.47-53
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• 2003

This paper describes the design of a 155 Mb/s multiplexer-demultiplexer chip. This device for a 2.5 Gb/s SDH based transmission system is to interleave the parallel data of 51 Mb/s into 155 Mb/s serial data output, and is to deinterleave a serial input bit stream of 155 Mb/s into the parallel output of 51 Mb/s The input and output of the device are TTL compatible at the low-speed end, but 100K ECL compatible at the high-speed end The device has been fabricated with a 0.7${\mu}m$ BiCMOS gate array The fabricated chip shows the typical phase margin of 180 degrees and output data skew less than 470 ps at the high-speed end. And power dissipation is evaluated under 2.0W.

• Korean Journal of Optics and Photonics
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• v.16 no.3
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• pp.248-253
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• 2005

We designed and fabricated a compact multi-mode interference (MMI) wavelength demultiplexer using the concept of 'Improved Quasi-State' modes. The output power and extinction ratio were improved by utilizing modal phase error which is specially occurred in low-index contrast. For a designed demultiplexer, the mode propagation analysis with effective index approximation shows significant improvement of extinction ratio to -25 dB for both $1.31{\mu}m\;and\;1.51{\mu}m$ wavelength region and the split-length was reduced about 1/5 of other MMI devices. The fabricated device shows successful characteristics for both 1.31 and $1.55{\mu}m$ wavelengths. These results demonstrate the potential of low-index materials system and the embossing process for photonic integrated circuits.

• Korean Journal of Optics and Photonics
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• v.16 no.5
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• pp.446-449
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• 2005

In a directional coupler, the design process requires repeated calculation of the characteristics of every changed structure, because it is generally difficult to expect the extinction ratio to be optimized over the entire variation of design parameters. In this paper, we systematically simulated the extinction ratio as a function of the design parameters, and analyzed the general tendency of that characteristic. In other words, we could find the generalized extinction ratio curve if the separation distance is normalized by the waveguide width. Here, the extinction ratio is shown to be increased as the normalized frequency (v) and the ratio (d) of the separation distance over the waveguide width were increased. For various structures with same ratio d, all corresponding extinction ratio curves as a function of v coincide with each other. We showed the usefulness of the generalized extinction ratio curve by applying it to the design and the fabrication of 1310/l550 nm demultiplexer, as it was convenient to design a shorter directional coupler with targeted extinction ratio from this curve.

• Proceedings of the Optical Society of Korea Conference
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• 1990.02a
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• pp.232-236
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• 1990

Optical waveguide was fabricated in the soda lime glass substrate using rapid thermal method. A chirped grating having period variation of 0.41 - 0.51${\mu}{\textrm}{m}$ on this waveguide for WDM was made. And then, arranging input and output optical fiber, wavelength division multiplexer with 5 channels in short wavelength region was realized. Experiment result of this WDM showed that wavelength spacing, 3 dB bandwidth, insertion loss and crosstalk were 5nm, 4nm, 40dB and less than -10dB, respectively.

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.166-167
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• 2002

광자 크리스탈은 빛의 진행을 제어할 수 있는 잠재적인 능력과 Wavelength Division Multiplexing 통신 시스템에서 광소자의 구현 가능성 때문에 활발히 연구가 진행 중이다. (1-3) 본 논문에서는 광자 크리스탈의 채널 드롭 터널링 현상을 이용하여 1x4 Demultiplexer의 구현 가능성을 고찰하였다. 광자 크리스탈을 이용해서 공진 시스템을 구성하였고, 중앙에 위치한 2개의 작은 디펙트의 크기를 조절하여 채널 드롭 현상을 관찰하였다. (중략)

• Proceedings of the Optical Society of Korea Conference
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• 2007.02a
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• pp.167-168
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• 2007

A novel holographic demultiplexer with multi-group has been firstly proposed and experimentally demonstrated using optimized CGH by genetic algorithm. For experimental demonstrations, a LCOS with 8.1um pixel size and spatial resolution of 1920X1200 is used.