30-fs pulses tunable across the visible with a 100-kHz Ti:sapphire regenerative amplifier

Reed, Murray K.; Armas, Michael; Steiner-Shepard, Michael K.; Negus, Daniel K.

doi:10.1364/ol.20.000605

Cited by 32 publications

(12 citation statements)

References 7 publications

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“…3 The bandwidths of the OPAs reported up to now are ϳ300 cm Ϫ1 which limit the shortest pulse width to about 30 fs. 4,5 The broadening of the bandwidth is the most important factor to obtain sub-10 fs pulses tunable outside the 800 nm region. Several methods were proposed for the spectral broadening in an OPA, 6,7 but they are rather complicated.…”

Section: ͓S0003-6951͑98͒02702-8͔mentioning

confidence: 99%

Noncollinearly phase-matched femtosecond optical parametric amplification with a 2000 cm−1 bandwidth

Shirakawa

Kobayashi

1998

Applied Physics Letters

140

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An optical parametric amplifier generating as short as 14 fs pulses in a visible region has been constructed in a noncollinear phase-matching configuration. The group-velocity matching between the signal and idler enormously broadens the gain bandwidth up to 2000 cm−1, which is mainly limited by the chirp of the seed pulses. Pulses shorter than 20 fs are tunable from 550 to 690 nm by scanning the delay-line of the pump beam.

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Section: ͓S0003-6951͑98͒02702-8͔mentioning

confidence: 99%

Noncollinearly phase-matched femtosecond optical parametric amplification with a 2000 cm−1 bandwidth

Shirakawa

Kobayashi

1998

Applied Physics Letters

140

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“…Thereby, lifetimes ͑t n1 10 6 3 fs͒ considerably shorter than the laser pulse duration can be analyzed. We further provide evidence that the relaxation dynamics of photoexcited bulk electrons is strongly influenced by cascade processes via hot electron scattering with the cold Fermi sea, while the initial energy dependent relaxation rates agree with predictions from Fermi liquid theory.The experiments were performed with a 200 kHz Ti:sapphire-seeded regenerative amplifier pumping an optical parametric amplifier (OPA) which outputs femtosecond pulses tunable from 470 to 730 nm [9]. The OPA output is compressed to 60 fs pulse duration and a thin (200 mm) beta barium borate crystal is used to generate second harmonic (UV) light.…”

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confidence: 99%

Ultrafast Electron Dynamics at Cu(111): Response of an Electron Gas to Optical Excitation

et al. 1996

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Time-resolved two-photon photoemission is used to directly investigate the electron dynamics at a Cu(111) surface with 60 fs laser pulses. We find that the time evolution of the photoexcited electron population in the first image state can be described only by solving the optical Bloch equations to properly account for coherence in the excitation process. Our experiments also provide evidence that the dynamics of photoexcited bulk electrons is strongly influenced by hot electron cascades and that the initial relaxation rates are in agreement with Fermi liquid theory. PACS numbers: 78.47.+p, 73.25.+i Ultrafast lasers have been extensively used to study the relaxation and recombination dynamics of excited bulk carriers in semiconductors [1-3] and nonequilibrium processes in laser-heated metals [4,5]. In contrast to techniques based on dynamic changes of macroscopic optical constants (e.g., transmission, reflection) time-resolved photoemission (TRPE) allows a direct measurement of the temporal evolution of the photoexcited electron distribution. In metals, where the initial relaxation dynamics is governed by ultrafast electron-electron ͑e-e͒ scattering, TRPE experiment have shown that complete thermalization of the nascent hot electrons to a Fermi distribution occurs on a time scale comparable to the electron-phonon ͑e-ph͒ relaxation time ͑ϳ1 ps͒ [5]. Image-potential states at metal surfaces provide an ideal system to study an excited electron gas and its coupling to a continuum of substrate excitations [6,7]. Time-resolved studies of the image state dynamics, however, provide a challenge due to the fast decay of the excitation on the order of few to tens of femtoseconds depending on their binding energy with respect to the bulk band structure.For coherent excitation of an electron gas with nearly transform limited laser pulses the rate of excitation is no longer given by Fermi's golden rule and cannot be described by simple rate equations. In order to properly account for coherent excitation as well as for energy relaxation and dephasing the optical Bloch equations must be solved [8]. This treatment reveals that the rate of excitation is not the highest when the field strength of the laser pulse reaches its maximum but rather when the pulse intensity decreases again. In this Letter we show that a precise measurement of the delay between the time profile of the pulse and the evolution of the excited state population, which critically depends on the energy relaxation time ͑T 1 ͒, allows us to analyze lifetimes which are considerably shorter than the laser pulse duration.We use time-resolved two-photon photoemission (2PPE) to investigate the response of an electron gas to femtosecond excitation at low excitation densities. Our experiments show that the transient population of photoexcited electrons in the ͑n 1͒ image state on Cu(111) is retarded by ϳ17 fs with respect to the time response of a two-photon process from the occupied surface state via a virtual intermediate state in the sp-band gap. The observed respon...

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“…Despite recent successful applications of solid state materials to generate femtosecond WLG and to use it for a seed pulse of OPA, [30][31][32][33] none of the solid state materials yielded stable WLG, because the damage threshold was so close to ͑or even lower than͒ the threshold of efficient WLG that immediate burning of the materials took place upon irradiation of the pump pulse. In contrast, both H 2 O and D 2 O could generate white light continuum in a stable manner.…”

Section: Results From the Wlg/opa Systemmentioning

confidence: 99%

“…The output power at wavelengths longer than 660 nm was negligibly small, although several reports noted successful OPA seeded by solid-state WLG above 660 nm. 30,31,33 On using a crystal with different cut angles, there was found to be no difference regarding the wavelength limit. Therefore, the limit is not determined by a phase matching condition in the crystal.…”

Section: A Tunability and Pulse Energymentioning

confidence: 98%

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Developments of widely tunable light sources for picosecond time-resolved resonance Raman spectroscopy

Uesugi

Mizutani

Kitagawa

1997

Review of Scientific Instruments

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Two systems of widely tunable light sources for picosecond time-resolved resonance Raman (ps-TR3) spectroscopy have been constructed using a 1 kHz ps-Ti:sapphire laser/regenerative amplifier system. Performance of the systems was examined in terms of pulse duration, spectral width, pulse energy, and shot-to-shot stability. One system, consisting of white light continuum seeder and β-barium borate optical parametric amplifier, demonstrated tunability in the 500–660 nm range with 1.3–2.1 ps pulse duration and 15 μJ pulse energy. The other system, consisting of a lithium triborate optical parametric generator in type II noncritical phase matching configuration and β-barium borate optical parametric amplifier, was found to yield visible pulses as high as 18 μJ with 1.5–2.4 ps of pulse duration in the 520–630 nm region. The shot-to-shot stability of generated pulses is less than 10% for both systems. Capability of the present systems is demonstrated by observing ps-TR3 spectra of nickel octaethylporphyrin in coordinating and noncoordinating solvents.

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30-fs pulses tunable across the visible with a 100-kHz Ti:sapphire regenerative amplifier

Cited by 32 publications

References 7 publications

Noncollinearly phase-matched femtosecond optical parametric amplification with a 2000 cm−1 bandwidth

Noncollinearly phase-matched femtosecond optical parametric amplification with a 2000 cm−1 bandwidth

Ultrafast Electron Dynamics at Cu(111): Response of an Electron Gas to Optical Excitation

Developments of widely tunable light sources for picosecond time-resolved resonance Raman spectroscopy

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