C. L. Gordon

Multiterawatt 30-fs Ti:sapphire laser system

A near-diffraction-limited transform-limited multiterawatt laser system that produces approximately 30-fs 125-mJ 800-nm pulses at a repetition rate of 10 Hz has been constructed. Methods for the control of femtosecond time-scale phase and amplitude distortions have been developed and implemented.

Time-gated imaging with an ultrashort-pulse, laser-produced-plasma x-ray source.

We demonstrate a contrast improvement of nearly a factor of 5 in a phantom medical x-ray image, using time-gated detection. This improvement is accomplished by temporal discrimination against scattered x-ray flux and may permit a significant reduction in patient x-ray exposure. A multiterawatt ultrashort-pulse laser-produced-plasma x-ray source (<1 ps) and a time-gated microchannel plate detector (~100 ps) are used.

Femtosecond-pulse-driven 10-Hz 41.8-nm laser in Xe ix

We report the observation of extreme UV lasing at 41.81 nm on the 4d95d1S0−4d95p1P1 transition in Xe ix, as proposed by Lemoff [ Opt. Lett.19, 569 ( 1994)]. A 10-Hz circularly polarized 800-nm laser pulse with an energy of ∼70 mJ and a duration of ∼40 fs is longitudinally focused to a peak intensity of >3 × 1016 W/cm2 over a length of 8.4 nm in a differentially pumped cell containing 12 Torr of Xe gas. Laser amplification was observed with an estimated gain coefficient of 13 cm−1 and a total gain of exp(11).

Methods for generation of 10-Hz 100-TW optical pulses

Phase and amplitude control during multiterawatt, ultrashort-pulse amplification is discussed. Methods for efficient energy extraction and scaling to 100-TW peak powers are outlined.

Time-gated medical imaging with ultrafast laser-plasma x rays

Laser-generated, hard x-rays are produced in a > 1018 W/cm2 focus of an ultrashort-pulse laser system. The application of ultrashort-duration, laser-generated x-rays to diagnostic medical imaging is discussed. Time-gated detection allows removal of scattered radiation, improved image quality and possible reduction of patient exposure. Methods for improvement of x-ray yield, design of appropriate drive lasers, and applications to mammography and angiography are also discussed.

Generation, measurement, and amplification of 20-fs high-peak-power pulses from a regeneratively initiated, self-mode-locked Ti:sapphire laser

We report the generation and measurement of 804 nm pulses with durations as short as 20 fs and with peak powers as high as 500 kW from a regeneratively initiated, self-mode-locked Ti:sapphire laser. Pulse duration is shown to decrease, and spectral content to increase, as intracavity power is increased. Control of intracavity focusing and a high-modulation-depth, acousto-optic modulator allow the intracavity power to be maximized. Cavity cubic phase error is minimized by correct design and placement of a GDD compensating prism pair. Methods for accurate determination of the pulse duration without assumption of pulse shape are discussed. Interferometric autocorrelation is accomplished with an interferometer which intrinsically balances dispersion and loss in each arm. Techniques for eliminating pulse distortions during amplification are also presented.

Multiterawatt amplification of ultrabroadband optical pulses: Breaking the 100 fs limit

A first of its kind, multiterawatt, ultrashort pulse laser system is described. The system is capable of producing 125 mJ, 35 fs, 800 nm pulsed with near diffraction limited beam quality at a 10 Hz repetition rate. Methods for control of phase and amplitude distortion during sub- 100 fs amplification are presented.

Multiterawatt femtosecond lasers for high field physics

Techniques for the control of femtosecond resolution phase and amplitude distortions during the amplification of ultrashort pulses are reviewed. Applications of a 4‐TW, 30‐fs, 10‐Hz, diffraction‐limited laser system are discussed and include ultrafast hard x‐ray generation for diagnostic imaging and field‐ionization‐driven XUV lasers.

Applications of a 30‐fs multiterawatt laser (A): generation and time‐gated imaging of laser‐produced x‐rays for medical applications

30‐fs, multiterawatt laser pulses are focused to intensities of >1018 W/cm2 onto a solid Ta target to generate x‐rays (10–30 keV) for diagnostic imaging. Time gated detection is demonstrated as a technique for removal of scattered radiation and for the improvement of image contrast by a factor of nearly 5.

Demonstration of a 10-Hz, 41.8 nm laser

We have observed lasing in Xe/sup 8+/ XUV ion lasers operating by collisional excitation that required solid density targets and pump laser pulse energies of several hundred joules, a 10 Hz, 800-nm laser pulse with an energy of -70 mJ and time duration of -40 fs is longitudinally focused in a differentially pumped cell containing 5 to 12 ton: of Xe gas.