• Title/Summary/Keyword: ultrashort laser pulse

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Tip-enhanced Electron Emission Microscopy Coupled with the Femtosecond Laser Pulse

  • Jeong, Dahyi;Yeon, Ki Young;Kim, Sang Kyu
    • Bulletin of the Korean Chemical Society
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    • v.35 no.3
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    • pp.891-894
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    • 2014
  • The ultrashort electron pulse, laser-emitted from the metal tip apex has been characterized and used as a probing source for a new electron microscope to visualize the morphology of the gold-mesh in the nanometric resolution. As the gap between the tungsten tip and Au-surface is approached within a few nm, the large electromagnetic field enhancement for the incident P-polarized laser pulse with respect to the tip-sample axis is strongly observed. Here, we demonstrate that the time-resolved tip-enhanced electron emission microscope (TEEM) can be implemented on the laboratory table top to give the two-dimensional image, opening lots of challenges and opportunities in the near future.

Efficient keV X-ray Generation from Irradiation of in-situ Produced Silver Clusters by Ti:sapphire Laser Pulses

  • Chakravarty, U.;Naik, P.A.;Kumbhare, S.R.;Gupta, P.D.
    • Journal of the Optical Society of Korea
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    • v.13 no.1
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    • pp.80-85
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    • 2009
  • An experimental study of energy absorption and x-ray emission from ultrashort laser pulse irradiation of in-situ produced solid clusters has been performed. Silver clusters produced by a 30 mJ, 300 ps laser pulse were irradiated up to an intensity of $3{\times}10^{17}\;W/cm^2$ by a 70 mJ, 45 fs compressed laser pulse from the same Ti:sapphire laser. Absorption of the laser light exceeding 70% was observed, resulting in an x-ray yield (>1 keV) of ${\sim}60{\mu}J$ pulse. This may constitute a much simpler means of intense x-ray generation using ultrashort laser pulses as compared to the irradiation of structured / pre-deposited cluster targets, and it offers higher x-ray conversion efficiency than that from gas clusters and planar solid targets.

Characteristics of multi-stage dye laser amplification and Second Harmonic Generation (색소레이저의 다단 증폭 및 SHG 특성)

  • 이영우
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.8 no.4
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    • pp.946-949
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    • 2004
  • We obtained ultra-short single pulse with an energy of 80 uJ from Distributed feedback Dye laser. Using three stages of amplifiers constructed by two stages of dye amplifiers and one bethune cell amplifier, we obtained high power pulse and second harmonic generation with BBO in ultraviolet region.

Three stage amplification of Distributed Feedback Dye Laser (Distributed Feedback Dye Laser의 3단 증폭특성)

  • 이영우
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2004.05b
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    • pp.339-341
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    • 2004
  • We obtained ultra-short single pulse with an energy of 80 of from self Q-switched Distributed Feedback Dye Laser. Using three stages of amplifiers constructed by two stages of dye amplifiers and one bethune cell amplifier, we obtained high power pulse and second harmonic generation with BBO in ultraviolet region.

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Novel Design of Ultrashort Pulse Excimer Laser Amplifier System II (Temporal Gain Control and Phase Distortion/ASE Characteristics)

  • Lee, Young-Woo
    • Journal of information and communication convergence engineering
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    • v.1 no.4
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    • pp.228-232
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    • 2003
  • The previous design work for very large final amplifier pumped by electron beam module was described from the point of view of energy characteristics. In this work, the design problems for phase front distortion, ASE, and gain control in large aperture amplifier are presented in detail.

Effects of transient thermo reflectance on the thermal responses of metal thin film exposed to ultrashort laser heating (극초단 펄스레이저 광이 입사된 금속박막의 열적반응 중 비정상반사율의 영향)

  • 박승호;국정진
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.11 no.4
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    • pp.528-536
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    • 1999
  • This work studies the effects of transient reflectance on the thermal responses of a metal(gold) thin-film during ultrashort laser heating. The heating process is calculated using the conventional conduction model (parabolic one-step: POS), parabolic two-step model (PTS) with and without variable properties, hyperbolic two-step model (HTS). Results from the HTS model are very similar to those from the PTS model, since the laser heating time in this study is greater than the electron relaxation time. PTS model with variable properties, however, results in totally different temperature profiles compared to those from POS models or calculation with constant properties. Transient reflectances are estimated from electron temperature distributions and based on the linear relationship between the electron temperature and complex dielectric constants. Reflectance of the front surface can be changed with respect to dielectric constants, while those of the rear surface remain unchanged.

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Bandwidth Analysis of High-order Pulse for the Transmission of Ultrashort Laser Pulses (극초단펄스 전송을 위한 고차원펄스의 스펙트럼 대역 분석)

  • 전진성;조형래;오용선
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 1999.05a
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    • pp.237-242
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    • 1999
  • In this paper, we analyze transmission characteristics of ultrashort laser pulses using the property of high-order pulses which are systematically obtained following their orders. The high-order pulses are easily derived from a modified PRS system model. But we make clear they are very useful to cover wider area and more accurate transmission characteristics of ultrashort pulses than Gaussian or Sech pulse approximations used conventionally. This may be based on the fact that the spectra and bandwidths of the high-order pulses are beautifully related to their orders. first modifying the generalized PRS system model, we propose a new model for deriving any type of high-order pulse. And we offer a novel analysis method of ultrashort pulse transmission which has any shape and FWHM, using the proposed model. In addition, by fixing the pulse range $\tau$=1(ps) and varying the order of the pulse from n:1 to n=100, we obtain spectra of ultrashort pulses with 1(ps)-150(fs) FWHM's, which are widely used in fiber communications. As a one-step further, we derive PSD's of their pulse trains when they are applied to Unipolar signaling scheme. These PSD's are decided in the range of possible pulse intervals. All of these results are not only coincided with some conventional experimental works but also will be applied to any pioneering ultrashort pulse in the future.

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A Novel Spectral Analysis of Ultrashort Laser Pulses Using Class-2 PRS Model (Class-2 PRS 모델을 이용한 극초단레이져펄스의 스펙트럼 분석)

  • 전진성;조형래;오용선
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 1999.11a
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    • pp.177-183
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    • 1999
  • In this paper, we analyze transmission characteristics of ultrashort laser pulses using the property of Raised-cosine pulse which are systematically obtained following Class-2 PRS model. The high-order pulses are easily derived front a modified PRS system model as Class-1 PRS model. This may be based on the fact that the spectra and bandwidths of the high-order pulses are beautifully related to their orders. And we make clear they are very useful to cover wider area and more accurate transmission characteristics of ultrashort pulses than Gaussian or Sech pulse approximations used conventionally. First modifying the generalized PRS system model, we propose a new model for deriving any type of high-order pulse. And we offer a novel analysis method of ultrashort pulse transmission which has any shape and FWHM, using the proposed model. In addition, by fixing the pulse range $\tau$=1(ps) and varying the order of the pulse from n=1 to n=100, we obtain spectra of ultrashort pulses with 1(ps)-100(fs) FWHM's, and width of FWHM in the Class-2 PRS model 50~100(fs) smaller than Class-1 PRS model. As a one-step further, we derive PSD's of their pulse trains when they are applied to Unipolar signaling scheme. These PSD's are derided in the range of possible pulse intervals. All of these results are not only coincided with some conventional experimental works but also will to applied to any pioneering ultrashort pulse in the future.

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UV ultra-short laser pulse generation and amplification (UV 극초단 레이저 펄스의 발생과 증폭)

  • 이영우
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2004.05b
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    • pp.324-326
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    • 2004
  • We have obtained ultra-short pulses with a wavelength of 616 nm from a Distributed Feedback Dye Laser pumped by excimer laser. Using the second harmonic generation, we obtained ultra-short pulse at 308nm in ultraviolet region and also performed amplification in 3 stages of XeCl amplifiers.

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