• Title/Summary/Keyword: Femto second laser pulse

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Characteristics of the Femto-second Pulsed Laser Ablation according to Feed Velocity on the Invar Alloy (펨토초 레이저의 이송속도에 따른 Invar 합금의 어블레이션 특성)

  • Chung, Il-Young;Kang, Kyung-Ho;Kim, Jae-Do;Sohn, Ik-Bu;Noh, Young-Chul;Lee, Jong-Min
    • Journal of the Korean Society for Precision Engineering
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    • v.26 no.3
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    • pp.25-31
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    • 2009
  • Femto-second laser ablation with the various feed velocities of the Invar alloy and the micro surface milling for the processing condition were studied. We used a regenerative amplified Ti:sapphire laser with a 1kHz repetition rate, 184fs pulse duration time and 785nm wavelength. Femto-second laser pulse was irradiated on the Invar alloy with the air blowing at the condition of various laser peak powers and feed velocities. An ablation characteristic according to feed velocity of the Invar alloy was appeared as the non-linear type at different zone of energy fluence. The micro surface milling of the Invar alloy using a mapping method was investigated. The optimal condition of micro surface milling was laser peak power of 22.8mW, feed velocity of 1 mm/s, beam gap of $1{\mu}m$. With the optimal processing condition, the fine rectangular shape without burr and thermal damage was achieved. Using the femto-second laser system, it demonstrates excellent tool for micro surface milling of the Invar alloy without heat effects and poor edge.

The Characteristics of Terahertz Electromagnetic Pulses by Different Bias Voltage (전압 변화에 따른 테라헤르츠 전자기 펄스의 변화 특성)

  • 전태인;김근주
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2001.05a
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    • pp.479-482
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    • 2001
  • We have measured terahertz electromagnetic pulses when DC voltage from V up to 90V is applied to the transmitter chip excited by femto-second laser pulse. The femto-second excitation laser pulse was injected to transmitter chip. Finally, we are observed the amplitude of electromagnetic pulse and variation of spectrum. Consequently, the amplitude of spectrum was increased to high frequency according to increase of voltage. At that time, the signal-to-noise rate(SNR) is increased from 250:1 to 10, 000:1.

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A Study on the Improvement of Resolution of Optical Coherence Tomography System Using Femto-Second Laser (펨토초 레이저를 이용한 OCT 시스템의 분해능 향상에 관한 연구)

  • Yang, Sung-Kuk;Park, Yang-Ha;Chang, Won-Suk;Oh, Sang-Ki;Kim, Hyun-Duk
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.18 no.6
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    • pp.31-36
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    • 2004
  • Optical coherence tomography system has been extensively studied because it has some advantages such as imaging of high resolution, low cost, and compact size configuration. In order to obtain high resolution of OCT system we configured OCT system using a femto-second laser. We measure the pulse width using autocorrelator function because a femto-second laser is ultra short pulse. And we measured the practical resolution using theoretical equation and the measurement of reference sample. It is confirmed that the proposed OCT system has 1.5 times higher resolution and un distinctive cross-sectional image than OCT system with SLD as a light source.

Ultrashort Optical Pulse Generation at 10 GHz by Pulse Compression of Actively Mode-Locked Fiber Laser Output (능동 모드잠금 광섬유 레이저 출력의 펄스 압축에 의한 10 GHz 극초단 광 펄스 발생)

  • Seo, Dong-Sun;Weiner, Andrew M.
    • Journal of IKEEE
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    • v.9 no.2 s.17
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    • pp.115-122
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    • 2005
  • We report 400 femto-second highly stable, nearly transform-limited, pulse generation at 10 GHz in $1540{\sim}1550$ nm wavelength region by adiabatic soliton pulse compression of an actively mode-locked fiber ring laser output. Without using any supermode selection device, supermode beating noise has been suppressed below -123 dB/Hz, resulting less than 100 femto-second timing jitters at the noise band of $1\;kHz{\sim}100\;MHz$.

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Absolute Distance Measurement using Synthetic Wavelength of Femto-second Laser (펨토초 레이저의 합성파를 이용한 절대거리 측정)

  • Kim Yun-Seok;Jin Jong-Han;Joo Ki-Nam;Kim Seung-Woo
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.569-572
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    • 2005
  • Technological feasibility of using recently-available femtosecond ultra short pulse lasers for advanced precision length metrology is investigated with emphasis on absolute distance measurements with $10{\mu}m$ ??resolution over extensive ranges. The idea of using femtosecond lasers for the measurement of absolute distances is based on the fact that a short pulse train is a mode-locked combination of discrete monochromatic light components spanning a wide spectral bandwidth. The synthetic wavelength is created from the repetition frequency, $f_r$ of the femtosecond laser and for more precise resolution, higher-order harmonics of the repetition frequency may be selected as the synthetic wavelength by using appropriate electronic filters.

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Class Strengthening by Crystallization with Femto Second Laser Pulse (극초단파레이저를 활용한 결정화에 의한 유리의 강도 증진)

  • Moon P. Y.;Lee K. T.;Yoon D. K.;Ryu B. K.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2005.10a
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    • pp.171-174
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    • 2005
  • To improve the strength of glass is being studied in order to contribute to weight saving of flat panel displays. Generally, the strength achieved of glass-ceramics is higher as is the fracture toughness by the formation of a heterogeneous Phase inside glass. In this study, Ag-doped $45SiO_2-24CaO-24Na_2O-4P_2O_5$ glasses were irradiated to strengthen by crystallization using femto-second laser pulse. UV/VIS, Spectroscope, XRD, nano-indenter and SEM etc. irradiation of laser pulse without heat-treated samples was analyzed. Samples irradiated by laser had higher value$(4.4\~4.56{\ast}10-3Pa)$ of elastic modulus which related with strength of glass than values heat-treated samples and these are $1.2\~1.5$ times higher values than them of mother glass. This process can be applicable to the strengthening of thinner glass plate, and it has an advantage over traditional heat-treatment and ion-exchange method.

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Mechanical Property and Crystallization of Glass by Femtosecond Laser Pulses (Femto Second Laser Pulse에 의한 유리의 결정화 및 기계적 특성)

  • Cha, Jae-Min;Moon, Pil-Yong;Kim, Dong-Hyun;Park, Sung-Je;Cho, Sung-Rak;Ryu, Bong-Ki
    • Journal of the Korean Ceramic Society
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    • v.42 no.6 s.277
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    • pp.377-383
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    • 2005
  • Generally, the strength achieved of glass-ceramics is higher as is the fracture toughness, as compared with the original glass. This improvement is due to the microstructure consisting of very small crystals. In this study, Ag-doped $45SiO_2-24CaO-24Na_2O-4P_2O_5$ glasses were irradiated to strengthen by the crystallization using Femto second laser Pulses. Through the UV/VIS spectroscope, XRD, Nano-indenter and SEM etc., heat-treated and irradiation of laser pulses without heat-treated samples were analyzed. Two kinds of samples, heat-treated and laser irradiated without heat-treated samples, showed the peaks in the same wavelength near 360 nm. Especially, samples irradiated by 140 mW laser with XYZ stage having at the rate of 100$\~$l000 $\mu$m/s had the largest absorption peak among them, and heat-treated samples was shown lower absorption range than over 90 mW laser irradiated samples. Moreover, samples irradiated by laser had higher values ($4.4\~4.56{\times}10^{-3}(Pa)$) of elastic modulus which related with strength of glass than values of heat-treated samples and these are 1.2$\~$1 .5 times higher values than them of mother glass.

3D Packaging Technology Using Femto Laser (팸토초 레이저를 이용한 3차원 패키징 기술)

  • Kim, Ju-Seok;Sin, Yeong-Ui;Kim, Jong-Min;Han, Seong-Won
    • Proceedings of the KWS Conference
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    • 2006.10a
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    • pp.190-192
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    • 2006
  • The 3-dimensional(3D) chip stacking technology is one of the leading technologies to realize a high density and high performance system in package(SIP). It could be found that it is the advanced process of through-hole via formation with the minimum damaged on the Si-wafer. Laser ablation is very effective method to penetrate through hole on the Si-wafer because it has the advantage that formed under $100{\mu}m$ diameter through-hole via without using a mask. In this paper, we studied the optimum method for a formation of through-hole via using femto-second laser heat sources. Furthermore, the processing parameters of the specimens were several conditions such as power of output, pulse repetition rate as well as irradiation method and time. And also the through-hole via form could be investigated and analyzed by microscope and analyzer.

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The Femto Second Laser Induced Ablation on the Titanium Alloy for Various Beam Overlap Ratio (빔 중첩율에 따른 티타늄 합금의 펨토초 레이저 어블레이션)

  • Chung, Il-Young;Kang, Kyung-Ho;Kim, Jae-Do
    • Journal of the Korean Society for Precision Engineering
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    • v.27 no.11
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    • pp.17-23
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    • 2010
  • Titanium alloy is one of the hard processing materials made by the traditional manufacturing method because of the excellent mechanical strength. Ablation of titanium alloy is investigated by using a femtosecond laser which is a regenerative amplified Ti:sapphire laser with 1kHz repetition rate, 184fs pulse duration time and 785nm wavelength. Experiments are carried out under various ablation conditions with different pulse overlap ratios for the rectangular shape and micro hole. Test results show that the ablation characteristic according to pulse overlap ratio of titanium alloy seems to be as non-linear type at the different zone of energy fluence. The optimal condition of rectangular shape processing is obtained at the laser peak power 1.3mW, pulse overlap ratio of 90%, beam gap of $1\;{\mu}m$. The micro hole has a good quality from the pulse overlap ratio of 99% at the same laser peak power. With the optimal processing condition, the fine rectangular shape and micro hole without burr and thermal damage are achieved.

Femto-second Laser Ablation Process for Si Wafer Through-hole (펨토초 레이저 어블레이션을 이용한 Si 웨이퍼의 미세 관통 홀 가공)

  • Kim, Joo-Seok;Sim, Hyung-Sub;Lee, Seong-Hyuk;Shin, Young-Eui
    • Journal of the Microelectronics and Packaging Society
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    • v.14 no.3
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    • pp.29-36
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    • 2007
  • The main objectives of this study are to investigate the micro-scale energy transfer mechanism for silicon wafer and to find an efficient way for fabrication of silicon wafer through-hole by using the femtosecond pulse laser ablation. In addition, the electron-phonon interactions during laser irradiation are discussed and the carrier number density and temperatures are estimated. In particular, the present study observes the shapes of silicon wafer through-hole with $100\;{\mu}m$ diameter and it also measures the heat-affected area and the ablation depths fur different laser fluences by using the optic microscope and the three-dimensional profile measurement technique. First, from numerical investigation, it is found that the nonequilibrium state exists between electrons and phonons during laser irradiation. From experimental results, it should be noted that the heat-affected area increases with laser fluence, and the optimal conditions for through-hole formation with minimum heat affected zone are finally obtained.

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