• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.1097-1100
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• 2003

Tunable thermo-optic filter for WDM system was designed and fabricated. The basic structure of the filter was a Fabry-Perot resonator and the center cavity layer was poly-Si. Quardraple layers of low and high refractive index materials were used as DBR mirrors. Tuning and transmission efficiencies was measured and compared with the simulation results. Tuning range of 9.4 nm can be obtained by 64.7$^{\circ}C$ temperature changes and tuning efficiency was 0.144nm/K. The filter is to be assembled onto the micro optical bench with fiber optical path.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.238-239
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• 2000

The optical fibers are an interesting medium for effective tunable optical frequency conversion in the spectral range of UV, Visible, and near-IR through the nonlinear processes. A number of papers for developing the wideband and flat-gain amplifier for the WDM system applications through the combination of EDFA or thulium-doped fluoride fiber amplifier and Raman amplifier, are reported$^{(1)}$ . Even though a variety of papers related to Raman amplifications are published, the amplification with the feedback of the residual pump is not investigated yet. Accordingly, in this paper, we report the characteristics of forward Raman amplification by the simple and double-pass fiber Raman configuration through the feedback of residual pump beam. (omitted)

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.8B
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• pp.1048-1056
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• 2001

파장분할 다중 광전송 시스템으로의 적용을 위한 홀로그래픽 다채널 역다중화기를 제안하고, 소자 특성에 대한 이론적 예측 및 실험결과를 제시하였다. LiNbO3:Fe 결정에 다중 홀로그래픽 부피 격자채널을 기록하기 위해 각도 다중 기록 및 노출시간 계획을 적용하였으며, 노출시간 계획에 recycling 기법을 적용해 각 채널의 균일도를 향상시켰다. 본 논문에서 제안한 방식을 실험적으로 입증하기 위해 1590nm 파장영역에서 0.8nm 채널 간격을 갖는 8채널 역다중화기를 설계하고 해석하였으며, 실험결과 각 채널은 0.8∼0.92%의 회절효율, 0.38∼0.45nm의 3dB 통과대역, 0.7∼0.89nm의 채널간격 및 -26.98dB 이상의 채널 누화 억제 특성을 관찰하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.232-232
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• 2004

최근 초고속 광통신 시스템이 발달함에 따라, 광통신 시스템 및 초고속 광통신 시스템의 핵심 부품인 평면도파로형 분배기(Splitter) 및 결합기(Coupler), 파장분할 다중화소자(WDM), AWG(Arrayed Wave Guide) 필터와 같은 소자부품 수요가 급격히 늘고 있다. 그러나 이러한 소자를 생산하는 공정은 수공적인 방법에 의존하여 생산성 향상을 위한 자동화에 대한 요구가 시급하다 특히 소자(Devices)와 광섬유(Optical fiber) 사이의 광학적인 정렬(Alignment)과 접속(Attachment) 공정은 부품 성능 및 생산성 향상, 그리고 비용절감을 위한 가장 핵심적인 문제로 대두되고 있다.(중략)

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2431-2433
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• 1999

Phase errors of arrayed waveguide degrade the performance of AWG router, especially for dense WDM system. So it is necessary to measure the phase error and to compensate. The analysis method of the interference signal from the low coherence interferometer to measure the path length difference phase error is studied. The interference signal generated assuming the intentional path length difference errors of 0.1$\sim$0.4${\mu}m$ are analyzed and the results show that the path length difference phase error of ${\Delta}L$ within ${\pm}14^{\circ}$ of sampling phase error can be accurately measured.

• Journal of the Optical Society of Korea
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• v.18 no.5
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• pp.589-593
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• 2014

Terahertz (THz) communication has important applications in high-speed and ultra broadband wireless access networks. The THz modulator is one of the key devices in a THz communications system. Wavelength division multiplexing (WDM) can expand the capacity of THz communications systems, so research on multi wavelength THz modulators has significant value. By combining photonic-crystal and THz technology, a novel type of multi wavelength THz modulator based on a triple-lattice photonic crystal is proposed in this paper. Compared to a compound-lattice photonic crystal, a triple-lattice photonic crystal has a larger gap width of 0.196. Simulation results show that six beams of THz waves can be modulated simultaneously with high performance. This modulator's extinction ratio is as large as 34.25 dB, its insertion loss is as low as 0.147 dB, and its modulation rate is 2.35 GHz.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.3
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• pp.56-62
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• 1998

One of the key components to accomplish WDM all-optical network is an arrayed waveguide grating router. The spectral characterisitc of the ypeical arrayed waveguide grating rouger has parabolic shape, hence the bandwidth is limited. The spectral response of an optical filter should be as flat as possible for the reliable operation of the syste, because the center frequency of the optical source could be deviated in the actual system. In order to acquire these characteristics, we propose and design a new type of the arrayed waveguide grating router with a flat passband using the Fourier optics concept. The BPM simulation results of the new arrayed waveguide grating router with the flat passband show that the bandwideth is 0.8 nm at -1 dB, instertion loss about 6 dB, and the crosstalk less than -23 dB fro each cnannel, which is 1.6 nm(200 GHz) separated from the adjacent channel around 1550 nm wavelength range.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.293-297
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• 2002

본 연구는 파장 분할 다중화(WDM： Wavelength Division Multiplexing) 방식 전송 시스템 (Transmission System)에 사용되는 어븀 첨가 광섬유 증폭기(EDFA： Erbium-Doped Fiber Amplifier)의 이득 제어(Cain Control) 방법에 관한 것으로 어븀 첨가 광섬유에서 상호 이득 포화 (Cross Cain Saturation) 현상, 이득 비동질(Cain In-homogeneity) 특성, 그리고 어븀 이온의 밀도. 반전(Population Inversion)의 변화에 의해 출력되는 다 파장 광 신호들의 광세기가 각기 다르게 출력되는 현상을 고출력을 내도록 구성된 어븀 첨가 광섬유 증폭기와 고속 제어기를 구성하여 위 현상들을 억제하며 이득을 제어하기 위한 레이저 다이오드(Laser Diode : LD)의 제어전압 조사하고, 얻어 진 결과들을 토대로 이득 제어에 적합한 방법을 제시하고 제어기를 설계한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.6A
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• pp.511-518
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• 2007

One of the major issues that has to be carefully considered when upgrading current transport network capacity, is network scalability. A novel full-meshed connected ring expansion methodology and planning tool have been proposed. A 3 to 15 node expansion ring has been studied by demonstrating a dramatic system SNR improvement when the proposed planning tool was used. The results are that node output signal and optical SNR have been improved from -16dBm/10dB to +005dBm/21dB by NPOT.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.12
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• pp.2828-2833
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• 1997

In this paepr, we have proposed an enhanced TDM with WDM hybrid photonic switching architecture, which has much simpler configuration and requires less hard ware. the basic module consists of arrayed waveguide grating (AWG) for wavelength division, compressor and fiber delay lines for time division. When compared with other systems, we proved that the proposed switch is suitable for large capacity photonic switching system due to less complexity and lower cost in implementation than the previous ones.