• Korean Journal of Optics and Photonics
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• v.17 no.6
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• pp.556-563
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• 2006

We present a comprehensive study of a chirped pulse Ti:sapphire regenerative amplifier system operating at 1 kHz. Main constituents of the system are described in detail. The amplifier stage was first converted to a repetition rate-tunable kHz gain-switched nanosecond Ti:sapphire laser. Operation characteristics at different repetition rates such as build-up times of laser pulses, pump power-dependent output powers and pulse durations, damage thresholds, and tunability ranges were studied. Based on the results achieved, the switching time of the Pocket's cell used and the round trip numbers in the regenerative amplifier were optimized at 1 kHz. The output pulses with a pulse width of 50fs from a home-made Ken lens mode-locked Ti:sapphire oscillator were used as seed pulses. The pulses were expanded to 120ps in a grating stretcher prior to coupling into the 3-mirror amplifier cavity. After amplification and recompression, a stable 1kHz Ti:sapphire regenerative amplifier system, which delivers 85-fs, $320-{\mu}J$ pulses, was fully constructed.

• Journal of the Korean Ceramic Society
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• v.31 no.8
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• pp.815-822
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• 1994

Sessile drop studies of molten Al on single crystal sapphire substrate were conducted to understand the wetting behavior and interfacial reaction at Al/Al2O3 interface. To investigate the wetting mechanism, the variation in contact angle was determined with time. The contact angle obtained in this study decreased exponentially with time. This result means that the driving force for wetting is the reduction in interfacial energy between liquid Al and sapphire caused by the interfacial reaction. The closer examination revealed that the reaction was the dissolution of sapphire by molten Al. Ti has been frequently used to improve wetting on ceramic materials. Therefore, the influence of Ti content on the wetting behaviour was investigated in this work. The equilibrium wetting angles of pure Al, Al-0.3 wt%Ti, and Al-1.0 wt%Ti at 100$0^{\circ}C$ were 63$^{\circ}$, 59$^{\circ}$, and 54$^{\circ}$respectively. The difference is considered as the result of the change in interfacial energy caused by the reaction between Ti and sapphire and the interfacial reaction formed the reaction products of varying stoichiometry (TiO, Ti2O3, TiO2 etc.).

• Korean Journal of Optics and Photonics
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• v.10 no.2
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• pp.157-161
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• 1999

A Ti:Sapphire laser pumped by the HCP has been designed and fabricated to study the optimal pumping conditions for lasing. The fluorescence energy converter LD-490 has been used. The result showed that the threshold energy of Ti:Sapphire laser is 1.39 KJ and the best efficiency is $7.13{\times}10^{-3}$% at the concentration $1.0{times}10^{-3}$ Mol/l of LD-490 dye. However, the efficiencies were decreased with the decrease of dye concentrations. The maximum output energy was obtained at 50 Torr Ar pressure, when the input voltage was 15 kV. As a convert dye, BBQ, was added to LD-490 with the rate of 1:1, the output energy was increased, whereas the thereshold energy was decreased as 1.17 kJ.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.656-661
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• 2002

Multipass Ti:sapphire amplifier for the light source of lidar was developed in an angular-multiplexing, and the characteristics of output energy and spectrum was investigated. In the two-stage multipass amplifier, we obtained the maximum output energy of 42 mJ, the amplification gain of 21 dB and the output efficiency of 26% on the wavelength of 790 nm. In the tuning range of 715~930nm the spectral linewidth is 0.05 $cm^{-1}$ /. The conversion efficiencies of 35% for SHG at 780 m and 13% for THG at 390 nm are obtained respectively. The continuous tunabilities of 240~306 m UV region and 360~460 nm in deep-blue region could be achieved.

• Korean Journal of Optics and Photonics
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• v.7 no.3
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• pp.244-249
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• 1996

Multipass Ti:sapphire amplifier for the light source of DIAL was developed with an angular-multi-plexing, and the characteristics of output energy and spectra were investigated. As the characteristics of two-stage multipass amplifier, the maximum output energy was 22 mJ and the amplification gain was 20 dB on the wavelength of 790 nm. At that condition, output efficiency of the pumping energy was 18 percent. We obtained $0.15cm^{-1}$ (9.4 pm) as a spectral linewidth in the tuning range of 705~845 nm.

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.238-239
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• 2001

sub-30fs 펄스폭의 상용 Ti：sapphire 레이저시스템에 대한 펄스압축기 및 2차 조화파 발생기를 제작하여 특성을 평가하였다. 그림la에서 82MHz의 주파수로 모드록되는 상용 Ti：sapphire 레이저 (Spectra-Physics Millennia/Tsunami laser)의 출력이 반사경 Ml, M2를 거쳐 펄스압축기에 입사되고 압축되어 나온 펄스가 다시 M6, M7를 거쳐 2차 조화파발생기로 입사되는 2단구조로 설계되었다. 압축기에 입사되기전 평균파워는 파장 800nm에서 520mW로 측정되었으며, 측정된 스펙트럼 반치폭 47nm에 (그림 2a)에 대해 chirp-free sech$^2$t 펄스로 가정할 경우 본 레이저시스템의 변환한계 펄스폭은 14.5fs로 계산된다. (중략)

• Journal of the Optical Society of Korea
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• v.12 no.3
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• pp.186-191
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• 2008

A phase retrieval method using an error reduction algorithm is developed for reconstructing a wavefront aberration of an 100-TW Ti:sapphire laser pulse from the measurement of a focal spot. The phase retrieval method can successfully reconstruct a wavefront aberration of a 100-TW Ti:sapphire laser pulse, and the reconstructed wavefront aberration shows a good agreement with the wavefront aberration measured with a wavefront sensor. The effect of the dynamic range and the intensity noise on the reconstruction is also investigated in reconstructing a wavefront aberration of an 100-TW Ti:sapphire laser pulse.

• Proceedings of the Optical Society of Korea Conference
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• 1997.08a
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• pp.87-87
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• 1997

• Proceedings of the Optical Society of Korea Conference
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• 2005.02a
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• pp.140-141
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• 2005

• Proceedings of the Optical Society of Korea Conference
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• 2004.02a
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• pp.336-337
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• 2004