• Journal of the Institute of Electronics and Information Engineers
• /
• v.51 no.2
• /
• pp.15-18
• /
• 2014

This work studies a variable optical attenuator using a reflective type liquid crystal cell for optical switches. The proposed architecture is capable of comprising a compact and low voltage driving variable optical attenuator. The usefulness of the proposed architecture is demonstrated by showing characterization of the liquid crystal cell, temperature effects, and response characteristics of the architecture.

• Proceedings of the KIEE Conference
• /
• 2001.07c
• /
• pp.1832-1834
• /
• 2001

A new method of all optical packet header recognition scheme using a photorefractive hologram filter is presented. Wavelength encoded packet that has the header of a specific wavelength is assumed and the photorefractive filter can detect the wavelength. Concatenated electronics drives the optical switch to route the $\lambda$-encoded optical packet. The delay time at the switched signals are measured and compared with the original data stream.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 1998.08a
• /
• pp.72.1-72
• /
• 1998

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

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.24 no.10B
• /
• pp.1832-1840
• /
• 1999

This paper proposed a network to implement all optical bidirectional BLSR/4 WDM/SHR allowing restoration in the event of a failure. The proposed network can provide a high degree of transparency using all-optical components with no electric implementation and effective failure restoration due to BLSR/4 WDM/SHR architecture. This paper also presented a genetic simulation model for the survivability analysis of the proposed BLSR/4 WDM/SHR under failure scenarios, the restoration performance of the proposed network is analyzed in terms of performance parameters such as propagation time, processing time, optical switch time.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.33A no.6
• /
• pp.197-205
• /
• 1996

Four types of three-waveguide optical switches are analyzed by measns of the coupled mode theory. Assuming that three proximate waveguides of an optical switch are identical and equally spaced, we examine the switching behavior for both cases where an incident beam is launched into 1) the outer waveguide, 2) the center waveguide. For each beam-launching case, switching voltage is applied so that three waveguides refractive indices be detuned 1) symmetric, 2) anti-symmetric. It is concluded that only three types of optical switches out of four an perform the switching operation. We derive the switching conditions for ach of three possible types and draw the corresponding switching diagrams.

• Proceedings of the Optical Society of Korea Conference
• /
• 2000.02a
• /
• pp.78-79
• /
• 2000

재구성이 가능한 광 크로스-커넥트(optical cross connect)는 전광 네트워크를 구성하기 위한 핵심소자 중의 하나이다. 일반적인 구조의 파장분배기는 공간분할 스위치(space division switch)를 두 쌍의 파장 다중화기(multiplexer)와 역다중화기(demultiplexer)의 가운데에 삽입하여 구현된다$^{(1)}$ . 최근에, 광섬유 브래그 격자와 광스위치 쌍을 직렬 연결하여 재구성이 가능한 광 크로스-커넥트가 제안되었다$^{(2)}$ . 그러나, 이 구조는 광신호에 따라 광섬유 브래그 격자에 반사되면서 겪는 광스위치에 의한 삽입손실이 다르다는 문제점이 있다. 이러한 문제를 해결하기 위하여 본 논문에서는 한 쌍의 파장 다중화기/역다중화기와 파장가변 광섬유 브래그 격자를 이용한 새로운 구조의 광 크로스-커넥트를 제안하고자 한다. 또한, 제안된 구조는 일반적인 구조의 파장분배기에 비해 파장 다중화기/역다중화기의 개수를 반으로 줄일 수 있는 장점이 있다. (중략)

• Current Optics and Photonics
• /
• v.1 no.3
• /
• pp.239-246
• /
• 2017

A compact plasmonic switching scheme, based on the phase change of a thin-film chalcogenide material ($Ge_2Sb_2Te_5$), is proposed and numerically investigated at optical-communication wavelengths. Surface plasmon polariton modal analysis is conducted for various thicknesses of dielectric and phase-change material layers, and the optimized condition is induced by finding the region of interest that shows a high extinction ratio of surface plasmon polariton modes before and after the phase transition. Full electromagnetic simulations show that multiple reflections inside the active region may conditionally increase the overall efficiency of the on/off ratio at a specific length of the active region. However, it is shown that the optimized geometrical condition, which shows generally large on/off ratio for any length of active region, can be distinguished by observing the multiple-reflection characteristic inside the active region. The proposed scheme shows an on/off switching ratio greater than 30 dB for a length of a few micrometers, which can be potentially applied to integrated active plasmonic systems.

• Proceedings of the IEEK Conference
• /
• 2001.06a
• /
• pp.375-378
• /
• 2001

A 640Gb/s very advanced ATM switching system using 0.25um CMOS VLSI, 40 layer ceramic MCM and 10Gb/s, 8 wavelength 8$\times$8 optical WDM interconnection has been fabricated. To break though the interconnection bottleneck, optical WDM interconnection is used. It has 20Gb/s 8 wavelength 8$\times$8 interconnection capability. It realizes 640Gb/s interconnections within a very small size. Preliminary tests show that 800b1s ATM switch MCM and optical WDM interconnection technologies can be applied to future high speed broadband networks

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.37 no.9
• /
• pp.23-30
• /
• 2000

The performance of two types of surface reflecting all-optical switches with InGaAs/InAlAs multiple quantum wells are investigated. The absorption spectra and the refractive index changes of the quantum well are calculated for various pump and probe beam intensities and device conditions. From theses results, on ON/OFF ratio and switching speed of the two switches are compared. It is shown that the switch using DBR has higher ON/OFF ratio and higher switching speed than the switch without DBR.