• Title/Summary/Keyword: Grating interferometer

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High resolution linear scale using collimated LASER (레이저를 이용한 광학식 리니어 스케일의 분해능 향상에 관한 연구)

  • 박윤창;정경민
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 1999.05a
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    • pp.170-174
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    • 1999
  • The main scale of linear scale greatly affects on the precision of displacement measurement. Especially when needing the long range measurement, the length of main scale should be increased accordingly. In this paper, we propose a linear scale that uses laser interference pattern as main scale for long range measurement. The linear scale is similar to Michelson interferometer excepting that the reference mirror is tilted so as to obtain interference fringe pattern and a grating panel is attached on a quadratic photo diodes. Four kinds of grating having phase differences of 0, $\pi$ /4, $\pi$ /2, 3 $\pi$ /4 are arranged on the panel. The experimental results show that signals of - quadratic photo diode, A, B,$\overline{A}$ and $\overline{B}$ are cosine wavelike and successive signals have phase difference of $\pi$/4 each other. So the proposed method can achieve improved measurement resolution.

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Pitch Measurement of 150 nm 1D-grating Standards Using an Nano-metrological Atomic Force Microscope

  • Jonghan Jin;Ichiko Misumi;Satoshi Gonda;Tomizo Kurosawa
    • International Journal of Precision Engineering and Manufacturing
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    • v.5 no.3
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    • pp.19-25
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    • 2004
  • Pitch measurements of 150 nm one-dimensional grating standards were carried out using a contact mode atomic force microscopy with a high resolution three-axis laser interferometer. This measurement technique was named as the 'nano-metrological AFM'. In the nano-metrological AFM, three laser interferometers were aligned precisely to the end of an AFM tip. Laser sources of the three-axis laser interferometer in the nano-metrological AFM were calibrated with an I$_2$ stabilized He-Ne laser at a wavelength of 633 nm. Therefore, the Abbe error was minimized and the result of the pitch measurement using the nano-metrological AFM could be used to directly measure the length standard. The uncertainty in the pitch measurement was estimated in accordance with the Guide to the Expression of Uncertainty in Measurement (GUM). The primary source of uncertainty in the pitch-measurements was derived from the repeatability of the pitch-measurements, and its value was about 0.186 nm. The average pitch value was 146.65 nm and the combined standard uncertainty was less than 0.262 nm. It is suggested that the metrological AFM is a useful tool for the nano-metrological standard calibration.

Wavelength Separation Add/drop Mu Multiplexer with the Various Network Topology (다양한 망구현이 가능한 파장분리형 광 애드/드롭 다중화기)

  • 강현서;이동열
    • Proceedings of the IEEK Conference
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    • 2001.06a
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    • pp.209-212
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    • 2001
  • We Propose a novel structure add/drop multiplexer based on an all-fiber Mach-Zehnder interferometer and fiber Bragg grating. In this structure, wavelength separation is achieved by adjusting the amount of the phase shift in the Mach-Zehnder interferometer. The proposed add/drop multiplexer drops a part of signal at a specific wavelength and transmit the remnant of the signal to the different node separated wavelength in WDM network.

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Implementation of the OADM Using FBG (FBG를 이용한 OADM의 구현)

  • 김기중;신희성;손용환;장우순;정진호
    • Proceedings of the IEEK Conference
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    • 2002.06a
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    • pp.219-222
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    • 2002
  • In this paper, we propose the OADM based on a Mach-Zehnder interferometer(MZI) with FBG(fiber Bra-gg grating) in the interferometer arms. The OADM us ing FBG and MZI is able to minimize system and red uce weight. We analyze output\ulcorner characteristics of OAD-M, and present the optimum design data through the computer simulation, and obtain the good experimental results. Also, the proposed OADM is suitable to DWD-M(Dense WDM) system because it has the narrow 1-inewidth.

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The Optical Add-Drop Multiplexer for DWDM Using Fiber Bragg Grating (FBG를 이용한 DWDM용 광 Add-Drop 다중화기에 관한 연구)

  • 손용환;신희성;허주옥;장우순;정진호
    • Proceedings of the IEEK Conference
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    • 2001.06a
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    • pp.237-240
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    • 2001
  • Dense Wavelength division multiplexing(DWDM) lightwave system requires multiplexer, demultiplexer and optical filter. In this paper, thus, we propose the Add-Drop Mux/Demux based on a Mach-Zehnder interferometer(MZI) with fiber Bragg grating(FBG). The Add-Drop Mux/Demux using FBG and MZI is able to minimize system and reduce weight. We also analyze output characteristics of Add-Drop Mux/Demux and present the optimum design data through the computer simulation.

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Mechanically induced Mach-Zehnder interferometers based on long-period fiber grating pair (기계적으로 구현된 장주기 광섬유 격자 Mach-Zehnder 간섭계)

  • 장현수;조준용;이경식
    • Korean Journal of Optics and Photonics
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    • v.14 no.4
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    • pp.365-368
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    • 2003
  • We have demonstrated mechanically induced Mach-Zehnder interferometers (MZI) based on a long-period fiber grating pair. The transmission spectra, the interference fringes, and the fringe spacing of the long-period fiber grating pairs have also been investigated experimently and analytically. The fringe spacings of the fabricated LPG pairs agree well with the theoretical results.

Grating fabrication for DFB laser diode using holographic interferometer system (DFB 레이저 다이오드를 위한 홀로그래픽 시스템을 이용한 회절격자 제작)

  • 강명구;오환술
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.33A no.6
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    • pp.108-113
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    • 1996
  • Periodic gratings for 1.55$\mu$m distributed feedback laser diode (DFB LD) have been fabricated by a holographic interference exposure system using an etalon stabilized Ar ion laser. We obtain a good development condition at developer concentration of 65% and obtain etching rate of 1000$\AA$/min at 20.deg. C by the mixed solution HBr:HNO$_{3}$:H$_{2}$O(1:1:10 in volume ratio). We obtain good first order grating with period of 2400${\AA}[\pm}2{\AA}$ at etching time of 45 sec from grating period and diffraction efficiency measurement, and SEM observation of grating fabricated on InP substrate.

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A study on tunable Add/Drop filter using Fiber Bragg Gratings (광섬유 bragg grating을 이용한 가변형 add/drop 필터에 관한 연구)

  • 박무윤;박광노;이경식;원용협;이상배
    • Journal of the Korean Institute of Telematics and Electronics S
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    • v.34S no.5
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    • pp.15-24
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    • 1997
  • We propose a tunable add/drop filter in a form of an all-fiber mach-zehnder interferometer iwth one bragg grating at each arm. This device can be tuned by inducing a strain in the bragg grating. We also theoretically analyze the outut characteristics of the tunable add/drop filter. As a result of simulation, we know that the proposed tunable add/drop filter works well. When 2*10$^{-3}$ of strain is induced, the reflected spectrum shifts about 3nm. And its reflected spectral width is about 0.3nm. In this case roughly 5 channels can be tuned, assuming the channel spacing is 0.3nm. When the pathlengths of the both arms are not the same, the transmissivities at the add and output ports and the reflectivity at the tap port varies sinusoidally with the pthlength difference. To maintain the transmissivities above 90% in the wavelength tuning range of 20nm the pathlength difference less than 16.mu.m is required.

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Using Pulse-Front Tilt to Measure Laser Pulses Less Than 100 Picoseconds in Duration

  • Jeong, Hoon
    • Korean Journal of Optics and Photonics
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    • v.26 no.6
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    • pp.318-321
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    • 2015
  • We demonstrate a frequency-resolved optical grating (FROG) device for measuring the intensity and phase versus time of several-tens-of-picoseconds laser pulses, using a thick nonlinear optical crystal. The huge pulse-front tilt generated by a holographic grating increases the temporal range of the device, which can make a single-shot measurement of laser pulses less than 100 ps in duration. To verify the measurement technique, we generate double pulses using a Michelson interferometer. The measured duration of a single pulse is about 300 fs and the measured maximum delay of two pulses is 60 ps, which implies that the proposed FROG device can measure laser pulses with maximum pulse width of about 120 ps.