• Title/Summary/Keyword: Wave Optics

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Selective Extraction of a Single Optical Frequency Component from an Optical Frequency Comb (광 주파수 빗으로부터 단일 광 주파수 성분의 선택적 추출)

  • Han Seb Moon
    • Korean Journal of Optics and Photonics
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    • v.34 no.6
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    • pp.225-234
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    • 2023
  • Mode-locked pulse lasers have a temporal periodicity up over a short period of time. However, in the time-frequency domain, a pulsed laser with temporal periodicity is described as an optical frequency comb with constant frequency spacing. Each frequency component of the optical frequency comb in the frequency domain is then a continuous-wave (CW) laser with hundreds of thousands of single-frequency-component CW lasers in the time domain. This optical frequency comb was developed approximately 20 years ago, enabling the development of the world's most precise atomic clocks and precise transmission of highly stable optical frequency references. In this review, research on the selective extraction of the single-frequency components of optical frequency combs and the control of the frequency components of optical combs is introduced. By presenting the concepts and principles of these optical frequency combs in a tutorial format, we hope to help readers understand the properties of light in the time-frequency domain and develop various applications using optical frequency combs.

Quasi Phase-Matched Second Harmonic-Wave Generation based on Nonlinear-Optic Effect Utilizing Ti:PPLN Optical Waveguides (Ti:PPLN 광도파로를 이용한 비선형광학 기반의 의사 위상정합 2차 조화파 발생)

  • Jung, Hong-Sik;Jung, Young-Sik
    • Korean Journal of Optics and Photonics
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    • v.19 no.6
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    • pp.408-415
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    • 2008
  • The characteristics of a ferroelectric-domain inverted grating fabricated by applying a high-voltage pulse at room temperature in Ti-diffused channel waveguides in z-cut $LiNbO_3$ (Ti:PPLN) were examined for channel waveguide quasi phase-matched secondharmonic generation devices. The fabrication conditions of uniform periodic domain-inversion were examined. Ti:PPLN with period ${\Lambda}=16.6{\mu}m$ for SHG were fabricated and the performances were measured. A normalized SHG efficiency as high as 473 (%/W) was obtained with 49 mm interaction length.

Output characteristics and measurement of the gain coefficient of a pulsed Nd:YAG laser (펄스형 Nd:YAG 레이저의 출력특성과 이득계수 측정)

  • 박대윤
    • Korean Journal of Optics and Photonics
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    • v.10 no.1
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    • pp.53-57
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    • 1999
  • We established the laser oscillator using Nd:YAG crystal grown at Ssang Yong company in Korea and investigated the characteristics of oscillation, Q-switching and wave front of output beam. We measured the single pass gain by controlling the threshold input energy with two output couplers of different output reflectances. Moreover, we compared the gain measured by different output couplers with the gain directly measured by the laser amplifier. The peak power of Q-switching, the pulse width, and the single pass gain coefficient at the threshold energy were 1.5 MW, 30ns, and 0.0958 cm-$^1$ respectively and they were compared with those of the commercial Nd:YAG crystal. Our crystal was proved to be as good as the commercial crystal.

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Polarization property of dichromated gelatin hologram and it's application to holographic polarization separation element (Dichromated Gelatin 홀로그램의 편광 특성과 편광분리 소자 응용)

  • 이영락;임용석;곽종훈;최옥식;박진원;이윤우
    • Korean Journal of Optics and Photonics
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    • v.8 no.4
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    • pp.260-266
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    • 1997
  • Holographic optical elements for polarization separation (HPS) are fabricated in a dichromated gelatin(DCG) thin film of 7${\mu}{\textrm}{m}$ thickness. The polarization properties of HPS is characterized by measuring diffraction efficiency with several physical parameters like exposure time, incident angle and read-out polarization angles. The experimental data are compared with theoretical results based on Kogelnik's coupled wave theory, which shows good agreement. It is also found that the HPS element has a very high extinction ratio of polarization over 500:1 for S and P polarizations, respectively, with He-Ne laser wavelength. We also propose an optical switch optical interconnects by using HPS elements.

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A Study on a Hartmann Test of Optical Mirror for On-Machine Measurement of Polishing machine (광학면 연마기의 OMM을 위한 Hartmann Test 방법 연구)

  • 김옥현;이응석;오창진;김용관
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.1
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    • pp.40-45
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    • 2004
  • Recently, aspheric optical lenses and mirrors, which are harder to manufacture and measure than the conventional spherical ones, are widely used, particularly in electronic fabrication process. Generally, interferometric optical method is used for the measurement of spherical optical surface. However, the interferometric method for aspheric surface measurement is difficult because it needs a precise null corrector and strict environmental conditions such as constant temperature, humidity and vibrations. We have been studied on the manufacturing of aspheric optics to improve the surface profile accuracy and productivity using a corrective polishing process. For the corrective polishing, a practical method of On-Machine Measurement (OMM) is required. For this purpose, an optical OMM system has been studied using the Shach-Hartmann test, which is very robust to the practical polishing environment. The wavefront has been reconstructed from the measured data using the primary aberration polynomial function by the least squares fitting. The measured result of the OMM system shows that the maximum deviation is less than 200 nm for the one of commercial Fizeau interferometer Wyko 6000.

Development of an FMCW Radar Altimeter Simulator Using Optical Delay Lines (광 지연선을 이용한 FMCW 전파고도계 시뮬레이터 개발)

  • Lee, Jae-Hwan
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.28 no.3
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    • pp.208-216
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    • 2017
  • This paper presents the design method of an FMCW(frequency-modulated continuous-wave) altitude simulator which generates propagation delay signals according to target distances to test the radar altimeter. To improve the conventional RF method for creating delay signals, the simulator is designed by the RF-optics-RF method using optical delay lines. In addition, it is designed to simulate the Doppler shift and jamming that may occur in actual flight environment. In order to evaluate the performance of the developed simulator, the integration tests have been conducted with the radar altimeter. Through the test, we successfully verified the performance of the simulator.

Development of Propagation Loss Prediction Software for the Indoor V-Band Millimeterwave Communication Environments (V-밴드 밀리미터파 대역의 실내 통신환경 분석을 위한 경로손실 예측 소프트웨어 개발)

  • Chun, Joong-Chang
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.1 no.1
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    • pp.35-39
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    • 2008
  • In this paper, we have developed a propagation loss prediction software with GUI (Graphic User Interface) functions, based on the geometrical ray optics model, which can predict radio parameters for the deployment of wireless indoor network. The program has two numerical modules consisted with electrical image and ray launching methods to implement UTD theory. The simulated results are compared with reported data measured in the foreign building environments for office and '一' type corridor, and measured and simulated results for the propagation loss agree with each other quite well. Simulation results for '一' type corridor and 'T' type corridor propagation environment are shown for reference.

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Diffractive characteristics of the photorefractive gratings in $LiNbO_3$:MgO ($LiNbO_3$:MgO 결정에서 광굴절 격자의 회절 특성)

  • 이재철;장지웅;김준태;신승호
    • Korean Journal of Optics and Photonics
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    • v.10 no.5
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    • pp.391-395
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    • 1999
  • We present the measurement of the diffraction efficiency and response time of the photorefractive grating recorded in $LiNbO_3$ photorefractive crystal doped with 4%-mole MgO. Two laser sources were used in the experiments; frequency-doubled Q-switched Nd:YAG laser ($\lambda$=532 nm) and cw Ar-ion laser ($\lambda$=514.5 nm). The same optical geometry was also used in both experiments in order to maintain the experimental consistency. Using the two-wave mixing scheme in both experiments we measured the maximum diffraction efficiency in the range of beam intensity of 1.6~100 W/ $\textrm{cm}^2$, and the response times for both cases of recording and erasing. Two sets of results obtained from the experiments are compared and analyzed.

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Sensitivity analysis of 20:1 zoom infrared optical system with zernike polynomial coefficients (제르니케(Zernike)계수를 이용한 20:1 줌 적외선 광학계 민감도 분석)

  • 최세철;김현숙;김창우;김연수;이국환;김현규
    • Korean Journal of Optics and Photonics
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    • v.14 no.5
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    • pp.535-544
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    • 2003
  • The sensitivity analysis of a middle wave infrared optical system with 20: 1 zoom ratio is performed to analyze manufacturing and alignment tolerances, and to establish the alignment logic and the focus control strategy. The characteristics of the sensitivities of Zernike coefficients are investigated to all mechanical displacements and several zoom positions using Code-V Macro. From this result, the tolerances of manufacturing and alignment of the optical system are derived and the effective alignment logic is established. Futhermore, an effective focus control strategy is established to make the system simple and compact.

Determination of photorefrative constants in LiNbO$_3$ using second harmonic generation (제2고조파발생을 이용한 LiNbO$_3$의 중요 광굴절상수측정)

  • 김봉기;이범구
    • Korean Journal of Optics and Photonics
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    • v.12 no.3
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    • pp.230-234
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    • 2001
  • We report a simple method for determining photovoltaic constant and conductivities of any photorefractive crytals which have no inversion symmetry by utilizing the electric field dependence of non-phase-matched second harmonic generation. New theoretical expression for the electric field dependence of Maker fringes is derived and space charge field can be determined using this from the observed change of intensity of second harmonic wave. The photovoltaic constant, dark conductivity and photoconductivity are easily deduced from an analysis of the measured relaxation behavior of space-charge field at two different light intensities. We demonstrate this method for $LiNbO_3$ at 514.5 nm.4.5 nm.

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