• Journal of the Optical Society of Korea
• /
• 제9권3호
• /
• pp.119-122
• /
• 2005

Silica-based $2\times2$ thermo-optic (TO) switch using the MMI couplers which have a large fabrication tolerance of 110 (${\mu}m$ were fabricated and operated. Important features of the proposed switch are shown to be a polarization dependency loss of 0.1dB, an extinction ratio of 32.7dB, and a power consumption of 202.8mW.

• 한국광학회:학술대회논문집
• /
• 한국광학회 2003년도 하계학술발표회
• /
• pp.192-193
• /
• 2003

광센서로 이용되는 광섬유 브라고 격자(이하 FBG)는 주변 환경에 대한 반응을 공진파장의 이동으로 나타내기 때문에 이것을 측정하기 위해서는 광 스펙트럼 분석기(OSA)가 반드시 필요하다 그러나 상용화된 광 스펙트럼 분석기는 고가이며 부피가 커서 광섬유 격자가 광센서로 상용화되는데 걸림돌이 되어 왔다. 이런 단점을 보완하기 위해서 많은 연구가 진행되어 왔으며 그 중에서 가장 잘 알려진 기술로는 Mach-Zehnder Inteferometer(MZI) 같은 간섭계를 이용한 방법과 Fabry-Perot (FP) filter, acousto-optic filter, FBG-based filters 등과 같은 변조기를 사용하여 광신호를 전기 신호로 바꿔 실시간으로 측정하는 방법들이 있다. (중략)

• Journal of the Optical Society of Korea
• /
• 제18권6호
• /
• pp.739-745
• /
• 2014

We have demonstrated a $Ti:LiNbO_3$ electro-optic electric-field sensor utilizing a $1{\times}2$ Y-fed balanced-bridge Mach-Zehnder interferometric (YBB-MZI) modulator, which uses a 3-dB directional coupler at the output and has two complementary output waveguides. A dc switching voltage of ~25 V and an extinction ratio of ~12.5 dB are observed at a wavelength of $1.3{\mu}m$. For a 20 dBm rf input power, the minimum detectable electric fields are ~8.21, 7.24, and ~13.3 V/m, corresponding to dynamic ranges of ~10, ~12, and ~7 dB at frequencies of 10, 30, and 50 MHz respectively. The sensors exhibit almost linear response for an applied electric-field intensity from 0.29 V/m to 29.8 V/m.

• Journal of the Optical Society of Korea
• /
• 제18권6호
• /
• pp.639-645
• /
• 2014

In this paper, the scheme of a single module for simultaneous operation of all-optical computing circuits, namely half adder and half subtractor, are realized using semiconductor optical amplifier (SOA) based logic gates. Optical XOR gate by employing a SOA based Mach-Zehnder interferometer (MZI) configuration is used to get the sum and difference outputs. A carry signal is generated using a SOA-four wave mixing (FWM) based AND gate, whereas, the borrow is generated by employing the SOA-cross gain modulation (XGM) effect. The obtained results confirm the feasibility of our configuration by proving the good level of quality factor i.e. ~5.5, 9.95 and 12.51 for sum/difference, carry and borrow, respectively at 0 dBm of input power.

• ETRI Journal
• /
• 제28권6호
• /
• pp.826-829
• /
• 2006

A novel method for optical phase shaped binary transmission (PSBT) generation has been recently reported and experimentally evaluated. An amelioration of the optical signal-to-noise ratio (OSNR) sensitivity of the optical PSBT modulation format is proposed with the application of the concepts of enhanced electrical PSBT signal generation. Enhanced optical PSBT is proposed here as a modulation format producing a 0.7 dB gain in OSNR sensitivity compared to OPSBT, while maintaining a good robustness to group velocity dispersion: 100 ps/nm for enhanced optical PSBT and 120 ps/nm for optical PSBT, compared to 50 ps/nm for standard NRZ signals.

• Journal of the Optical Society of Korea
• /
• 제12권3호
• /
• pp.162-165
• /
• 2008

A novel planar lightwave circuit(PLC) triplexer using a three-waveguide interferometer(TWI) is proposed and examined using the transfer matrix and the beam propagation methods. The proposed triplexer consists of two three-waveguide couplers and three waveguides connecting the couplers. Simulation for the TWI triplexer shows the excess losses of 0.03 dB and 0.94 dB with the crosstalks of -22.3 dB and -14.5 dB in reception, respectively, for the wavelength of 1490- and 1550-nm, while showing the excess loss of 1.75 dB in transmission for the wavelength of 1310 nm. The proposed design shows compact feature as short as 11.5 mm for the refractive-index contrast of 0.45%.

• Journal of the Optical Society of Korea
• /
• 제18권1호
• /
• pp.65-70
• /
• 2014

This paper presents the simulation and design of an all-optical subtractor using a quantum-dot semiconductor optical amplifier Mach-Zehnder interferometer (QD-SOA MZI) structure consisting of two cascaded switches, the first of which produces the differential bit. Then the second switch produces the borrow bit by using the output of the first switch and the subtrahend data stream. Simulation results were obtained by solving the rate equations of the QD-SOA. The effects of QD-SOA length, peak power and current density have been investigated. The designed gate can operate at speeds of over 250 Gb/s. The simulation results demonstrate a high extinction ratio and a clear and wide-opening eye diagram.

• 한국정보통신학회논문지
• /
• 제12권5호
• /
• pp.956-962
• /
• 2008

바닷속과 같은 수중에서 1개의 광섬유에 다량의 배열형 광센서를 접속하여 광범위한 영역에서의 원격 측정도 가능한 광 CDMA 기반 광섬유 센서를 이용한 음파탐지 시스템을 제안한다. 그리고 제안 시스템에서 잡음특성을 이론적으로 분석하고 컴퓨터 시뮬레이션에 의하여 그 결과를 분석한다. 광 CDMA 기반 광섬유 센서를 이용한 음파탐지 시스템에서 센서의 측정 시간을 증가시키면 종래의 WDMA 방식을 적용할 경우 보다 많은 광센서가 접속 가능한 것을 알 수 있다.

• 한국광학회:학술대회논문집
• /
• 한국광학회 2003년도 하계학술발표회
• /
• pp.16-17
• /
• 2003

지난 수년간 인터넷 보급에 따른 급격한 통신량 증가에 따른 요구는 차세대 통신 기술인 WDM을 구축하게 되었고 이에 따라 WDM 라우팅 기술과 스위칭 기술이 절실히 필요로 하게 되었다. WDM에 있어서 다른 경로나 목적지로 신호를 보내기 위해서는 신호의 파장이 변환 되어야 하므로 신호의 파장변환은 라우팅에 있어 핵심적인 기술 중 하나로 인식되어지고 있다 현재 사용되어지고 있는 전광 파장 변환기는 주로 SOA (Semiconductor Optical Amplifier)의 비선형 특성인 XGM, XPM, FWM등을 이용한 것으로서 편광 민감성, ASE에 의한 SNR 감소, 신호크기 변형과 높은 가격으로 인해 안정적인 파장변환기로 쓰기에는 다소 무리가 있다. (중략)

• Journal of the Optical Society of Korea
• /
• 제18권3호
• /
• pp.230-235
• /
• 2014

Two-step quadrature phase-shifting digital holography based on the calculated intensity of a reference wave is proposed. In the Mach-Zehnder interferometer (MZI) architecture, the method only records two quadrature-phase holograms, without reference-wave intensity or object-wave intensity measurement, to perform object recoding and reconstruction. When the reference-wave intensity is calculated from the 2D correlation coefficient (CC) method that we presented, the clear reconstruction image can be obtained by some specific algorithm. Its feasibility and validity were verified by a series of experiments with 2D objects and 3D objects. The presented method will be widely used in real-time or dynamic digital holography applications.