Daniel K. Negus

Widely tunable femtosecond optical parametric amplifier at 250 kHz with a Ti:sapphire regenerative amplifier

A Ti:sapphire mode-locked regenerative amplifier system pumped with a single argon-ion laser produces 4-μJ, 170-fs pulse of 800-nm wavelength at a 250-kHz repetition rate. Part of this output is used to generate a high-beam-quality white-light continuum, while the rest is doubled to 400 nm and used to parametrically amplify visible components of this continuum to more than 100 nJ. Synchronized with the visible signal pulse tunable from 460 to 700 nm is an infrared idler pulse tunable from 2.4 to 0.9 μm.

Tunable ultraviolet generation using a femtosecond 250 kHz Ti:sapphire regenerative amplifier

A mode-locked Ti:sapphire regenerative amplifier system pumped with a single argon ion laser produces /spl mu/J energy 100 femtosecond pulses of 800 nm wavelength at 250 kHz repetition rate. Pumping a Type II BaB/sub 2/O/sub 4/ (BBO) optical parametric amplifiers (OPA) with this output generates 500 nJ infrared pulses and continuous tuning from 1.1 /spl mu/m to beyond 2.5 /spl mu/m. Difference frequency generation of the signal idler output from this OPA source in AgGaS/sub 2/ produces 60 nJ mid infrared pulses and continuous tuning from 2.4 /spl mu/m to beyond 12 /spl mu/m.

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

A 100-kHz mode-locked Ti:sapphire-seeded regenerative amplifier pumping an optical parametric amplifier generates femtosecond pulses tunable from 470 to 710 nm. This output was compressed with a pair of prisms to bandwidth-limited pulses of 80- to 40-fs duration and more than 150 nJ of energy. These tunable pulses were then bandwidth expanded through self-phase modulation in bulk material and further compressed to less than 30-fs duration.

Sub-100 Femtosecond Pulse Generation by Kerr Lens Mode-locking in Ti:Al2O3

Ti:Al2O3 has the available bandwidth for directly generating very short tunable pulses at high average power. Passive modelocking techniques have been described in the literature [1], [2]. We report 800mW at sub-100fs (when pumped with 8W) and 2.1W output with 120fs pulsewidth (pumped with 14W).

Review of cw high-power diode-pumped green lasers

Recent progress in pump sources and basic materials have allowed the production of commercially viable, high-power, diode-pumped, continuous-wave, green lasers. We will review the history and the technological developments that have allowed this progress.

Dynamics Of Solvated Electron Formation From Dna Irradiated By Intense Laser Pulses

Solvated electrons are formed in high yield and can be detected by transient absorption spectroscopy when calf thymus DNA is irradiated with laser pulses at 266 nm having peak intensities above 1014 W/m2. Approximately 20% of the initially appearing absorption strength decays with a time constant of 400 ps, while the remaining 80% is long-lived (> 10 ns). The decaying component may indicate geminate recombination of the photoejected electron. Spectral evidence suggests that the bases are the site of ionization. The signal is observed to depend nonlinearly on the excitation pulse energy, indicating that two (or more) excitation quanta at 266 nm are required to ionize DNA. An equimolar mixture of nucleosides shows a much lower quantum yield for electron formation; this is discussed in terms of an exciplex model for the DNA excited state.

An efficient diode-based Ti:sapphire ultrafast laser

175-mW of 50-fs pulses and 30-mW of SHG is generated by a Ti:sapphire ultrafast laser pumped with a 780-mW power 532-nm intracavity doubled Nd:YAG ring laser pumped with a single 4-W GaAlAs diode. Reducing the 532-nm power to 600-mW produced more than 100-mW from a prism compensated ultrafast laser and more than 75-mW from a GTI mirror compensated version.

Femtosecond pulse generation via Kerr lens mode-locking in Ti:A12O3

Abstract OnlyFEMTOSECOND PULSE GENERATION VIA KERR LENS MODELOCKENG IN ThA1203Daniel K. Negus, Luis Spinelli, Norman Goldblatt,Michael Steiner-Shepherd, John AmbroseoCoherent Laser Group3210 Porter DrivePalo Alto, California 94304Numerous methods have been demonstrated to produce tunable pulses from Ti:sapphire. Thereported results have ranged from 600ps down to 5Ofs with varying tunability. We describe a novel modelocking technique which utilizes the intensity dependent refractive index, n, of theTi: sapphire to generate a time-varying Kerr lens. The Kerr lensing effects are optimizedwithin a nonlinear resonator to create differential gain for modelocked operation as well assaturable absorption. In addition, the resulting high intensity pulses are shown to behave in a quasi-soliton manner in which the chirp introduced by SPM is precisely compensated byintracavity GVD compensation. Nearly transform limited sub-lOOfs pulses have beendemonstrated at high average power and typical system performance will be discussed.