• Korean Journal of Optics and Photonics
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• v.18 no.2
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• pp.162-166
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• 2007

In this paper, we propose a WDM optical true time-delay (OTTD) beam former for phased way antenna (PAA) systems. It is composed of a delay lines matrix and a multiwavelength source with discrete DFB laser diodes. The building block of a delay lines matrix is a $2\times2$ optical MEMS switch with proper fiber-optic delay line connected between cross ports. A $4\times3$ matrix using four DFB lasers has been fabricated with unit time-delay difference of 12 ps. Maximum time-delay error was measured to be -1.74 ps and +1.14 ps at a radiation angle of $46.05^{\circ}$, corresponding to error range of $-2.87^{\circ}\sim+1.88^{\circ}$. By measuring time-delays at six different RF frequencies from 5- to 10-GHz, we verified the true time-delay characteristic of our OTTD.

• Korean Journal of Optics and Photonics
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• v.21 no.5
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• pp.206-213
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• 2010

We fabricated and characterized a compact endoscopic catheter for optical coherence tomography. The optical delay line (ODL), composed of a cylindrical piezoelectric transducer (PZT) and an optical fiber, was operated with a 1 kHz sinusoidal driving wave in the time-domain. When the ODL was driven with a sinusoidal wave function, the axial scanning speed was 6 m/s and the axial acquisition rate was 2000 line/s at a depth of about 3 mm. Endoscopic OCT images of a human finger and earhole were successfully obtained with an image rate of ten frames per second.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.5
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• pp.1580-1584
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• 2010

In this paper, we made an analysis of the effective optical pulse stream generation. This is different from conventional approaches, which use fiber or waveguide delay line circuits. The optical pulse multiplication phenomenon occurs when the optical pulse's spectral width is greater than the transfer bandwidth of the coupler used. Therefore, the effective optical pulse stream generation can be controlled by using fiber couplers with different equivalent transfer bandwidths. The pulse separation spacing is controlled by number of cascaded coupler in optical loop mirror coupler scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.3A
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• pp.153-159
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• 2005

In this paper, we propose All-Optical WDM Buffer System for resolving the contention of Packets in Optical Packet Switching System. The proposed system consists of tunable wavelength converters based on SOA, N×N AWG, and fiber delay lines. This structure can reduce ASE and cross-talk noise because the contending packets are sent and buffered through each different path determined by a wavelength routing. We also performed buffering experiment for two contending WDM optical pulses with each 50ns width, and found that the contending problem is resolved well.

• Korean Journal of Optics and Photonics
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• v.5 no.4
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• pp.493-498
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• 1994

A fiber-optic matched filter with Cr/ Au film-deposited fiber-optic delay lines is fabricated for a possible application as photonic packet address detectors for an all-optical slotted ring network. Correlation waveforms for a set of 6-bit address codes with 2.5 Gb/s are produced by simulation. It is shown that the measured correlation outputs agree well with the calculated ones.d ones.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.5B
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• pp.529-536
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• 2001

광섬유 지연선로 정합 여파기를 광 패킷 어드레스 처리기로 사용한 완전 광 패킷 교환 노드들로 구성된 슬러티드 링 통신망에서 가우시언, 2차 초가우시언, 그리고 RZ 구형파 형태의 입력 광 펄스에 대한 노드의 패킷 오율 변화에 관하여 고찰하였다. 전송속도의 증가에 따라 모든 입력 펄스 형태에 대해 패킷오율이 증가하였고, 산탄 잡음의 영향이 크게 나타났다. 패킷 오율 $10^{-9}$에서 전송속도가 같은 경우에는 가우시언 펄스, 2차 초가우시언 펄스, RZ 구형파 순으로 첨두 파워가 증가한 반면, 펄스 에너지는 모든 펄스 형태에서 거의 같게 나타났다. 넓은 펄스폭을 갖는 가우시언 펄스는 대역폭 감소로 인해 잡음 전력이 감소하는 효과보다, ISI로 인한 각 어드레스 코드의 상관 출력레벨 변동으로 발생하는 파워 패널티 효과가 더 크게 나타났다. 따라서, ISI에 의한 영향을 최소화하기 위해서는 가우시언 펄스의 rms 폭을 1/(4B)이하로 유지해야 함을 알 수 있었다.

• Journal of KIISE:Information Networking
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• v.29 no.4
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• pp.405-411
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• 2002

Open interfaces in the optica] Internet have been progressed by OIF's ISI, ITU-T ASTN's CCI and IETF's GSMP extensions with optical switching. These open interfaces enable the separation between the control plane and the optical transport plane. This separation allows flexibility in the network, but it suffers more setup delay than the traditional switch-by-switch connection setup. We propose the parallel interworking model, which will reduce the connection setup delay in the open interface of optical Internet. Based on the switch controller's caching capability about networks states, the parallel interworking procedures between signaling protocol and GSMP protocol are performed in the switch controller. We simulated and evaluated our proposed parallel interworking model and the existing sequential interworking model in terms of a connection setup delay and a completion ratio. We observed that the completion ratios of the two interworking models were quite close. However the connection setup delay of parallel interworking model is improved by about 30% compared with that of the sequential interworking model.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.12
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• pp.1484-1493
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• 1992

In this paper, we propose the polarization coding of optical logic gates using filters and LCTV's, and represent the real-time system of an optical parallel adder to improve a carry propagation delay time. We fabricated a polarization filter for the polarization coding of a cell and an electrical system instead of an optical flip-flop which was necessary to an optical parallel adder. We used an optical fiber to play a part of decoding mask and interconnections in an optical parallel adder. The experimental results show that the polarization coding of a cell can represent 16 optical logic functions and that the implemented optical parallel adder can operate in real-time.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.11 s.353
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• pp.14-18
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• 2006

Optical interferometer is used for various optical measurement fields in optical metrology and biomedical measurements. In an optical interferometer, optical delay line has to change the optical path length of a reference arm to match with that of a sample in and it's speed was limited by reference arm movement speed. In this paper, we proposed an all-fibered RSODRapid Scanning-speed Optical Delay) without any mechanical movement, and we applied this system to optical interferometer. Experimental setup is consist of pulse laser source (center wavelength 1304nm, pulse width 30ps, repetition rate 10GHz), two phase modulators and dispersive shifted fiber. As experimental results, we obtain the maximum time delay of 11ps at 10MHz repetition rate, and it is easily tuneable the time delay by modulation frequency and modulation voltage.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.5
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• pp.1117-1122
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• 2005

This paper is studied the high-repetition rate optical-pulse stream generation using optical loop mirror coupler. With the recent development of the ultrahigh-speed optical time division multiplexed system, hish-repetition rate optical-pulse stream generation is necessary. This is different from conventional approaches, which use fiber or integrated waveguide delay line circuits. The high-repetition-rate optical-pulse multiplication phenomenon occurs when the optical pulse's spectral width is greater than the transfer bandwidth of the coupler used. From the analysis, the output repetition rate can be controlled by using fiber couplers with different equivalent transfer bandwidths. The pulse separation spacing is controlled by number of cascaded coupler in optical loop mirror coupler scheme.