Showing papers on "Femtosecond pulse shaping published in 1980"

Optoelectronic regenerative pulser

Abstract: The letter describes a new scheme for generating repetitive picosecond laser and electrical pulses in a controlled manner. The arrangement is a feedback loop containing a semiconductor diode laser, a photodetector, an amplifier and a time delay. The loop allows the laser to be driven by an ultrashort current pulse derived from the previous laser pulse. Optical and electrical pulses of less than 100 ps have been generated using GaAs-based lumped components. Monolithic integration of these components on a chip seems feasible with possible increase in speed.

Laser drilling with different pulse shapes

Abstract: Drilling in thin metal plates has been studied with two types of pulses from an ordinary flash‐lamp‐pumped Nd‐YAG laser. The drilling performance with a normal pulse consisting of a 200‐μs continuous emission preceeded by a few relaxation oscillations has been compared with that of a 200‐μs train of 0.5‐μs pulses. The pulse train was obtained by introducing a periodic low loss into the laser resonator with the frequency of the relaxation oscillations. It is shown that the use of the pulse train is much superior to the normal pulse for drilling in aluminium and similar metals.

Generation of arbitrarily shaped optical pulses in the subnanosecond to picosecond region using a fast electrooptic deflector

Abstract: New types of optical-pulse shaper and compressor in the subnanosecond to picosecond region are proposed, in which a fast electrooptic deflector is used together with Fourier optical elements (e.g., spatial fdter, lens, slit, grating, etc.). In the preliminary experiment using a LiTaO 3 electrooptic-deflector device and a CW 633 nm HeNe laser, various types of shaped pulse, for example, Gaussian, squared, triangle, and double-peak pulses, were obtained with 94 ps minimum duration.

A frequency stabilized compact high repetition rate TEA-CO 2 laser

Abstract: A compact atmospheric-pressure hybrid CO 2 laser utilizing a transverse double-discharge technique has been constructed and operated at moderate repetition rates. A pulse output energy of 80 mJ has been obtained under single-mode conditions at repetition frequencies of 100 Hz. Using the hybrid technique to obtain single-longitudinal-mode operation, we have been able to reach a 7 kHz long-term relative frequency instability between the TEA laser and a local oscillator. Measurements of the frequency sweeping during the pulse tail (chirp) are also presented along with a direct measurement of the resonant frequency pulling effect associated with the real part of the electric susceptibility of the gas. Limitations on the pulse repetition frequency for this laser configuration are also discussed.

Efficient optical pulse stacker system

Abstract: Method and apparatus for spreading and angle-encoding each pulse of a multiplicity of small area, short pulses into several temporally staggered pulses by use of appropriate beam splitters, with the optical elements being arranged so that each staggered pulse is contiguous with one or two other such pulses, and the entire sequence of stacked pulses comprising a single, continuous long pulse. The single long pulse is expanded in area, and then doubly passed through a nonstorage laser amplifier such as KrF. After amplification, the physically separated, angle-encoded and temporally staggered pulses are recombined into a single pulse of short duration. This high intensity output beam is well collimated and may be propagated over long distance, or used for irradiating inertial confinement fusion targets.

20-J nanosecond-pulse CO 2 laser system based on an injection-mode-locked oscillator

Abstract: Recent advances in injection mode locking and high-power 10 μm pulse selection have been incorporated into a high-power CO2 laser system built around a single 5 l TEA CO2 gain module. A pulse selected from a line-tuned [to P(20)] injection-mode-locked oscillator was amplified to produce a 20 J, 3 ns pulse with a main-pulse-to-prepulse contrast ratio of >107:1.

Optical pulse shaping device and method

Abstract: An optical pulse shaping device and methhod of shaping an optical pulse involves the use of a phase coherent multi-frequency light beam with an optical element consisting of a sample containing an absorption band with multiple holes. The holes are burned into the sample to selected depths at selected frequency locations, thereby permitting the relative phases and amplitudes of the input frequency components of the beam to be independently varied to arbitrary values. This system enables a generalized Fourier synthesis of optical pulses such as a laser with designed temporal profiles to be effected.

Cross-correlation studies of pulses from the double mode-locked CW dye laser

Abstract: A detailed investigation of the dual-wavelength pulse trains from the double mode-locked CW dye laser is made using cross-correlation measurements. Direct displays of pulse shapes and of the system jitter distribution are experimentally determined on a picosecond time scale. Techniques for determining the relative time of generation between the two double mode-locked pulse trains are also demonstrated. A variety of operating modes for this system is discussed in detail, providing further insight into the fundamental mechanisms involved in the production of the two pulse trains.

Pulse evolution in injection mode locked TECO2 lasers

Abstract: The pulse train evolution in an injection mode locked TECO2 laser has been investigated for a wide range of input pulse widths e.g., ranging from the cavity round-trip time to near the bandwidth-limited value for the system. Regimes in which pulse narrowing and pulse broadening occur have been identified and are discussed. The combined use of injection and saturable-absorber mode-locking techniques has produced reliable subnanosecond pulse trains from a large aperture TEACO2 laser.

Characteristics of the pumping pulse and the output laser pulse for a Cu/CuCl double pulse laser

Abstract: Characteristics of the pumping discharge pulse and laser pulse in a Cu/CuCl double pulse laser have been measured as a function of time delay, buffer gas pressure, and tube temperature. We have found that for otherwise fixed discharge conditions, pumping rates decrease as these quantities are increased. The shape of the laser pulse as a function of time delay is shown to be dependent on the rate of current rise of the pumping pulse. The length of time required by the pumping pulse to achieve threshold is found to be a function of time delay, buffer gas pressure, and tube temperature. The implications of this behavior for the role of metastable copper and its mode of relaxation are discussed.

Numerical investigation of the possible use of stimulated Brillouin scattering in laser fusion facilities

Abstract: Results are presented of calculations of the energy and temporal characteristics of a transient Stokes stimulated Brillouin scattering (STBS) pulse under saturation conditions. It is found that by using an STBS mirror operated in the transient regime, it is possible to improve the pulse contrast ratio, sharpen the leading edge, and shorten the pulse duration. Calculations are made of the propagation of a Stokes pulse through the amplifier stages of an iodine photodissociation laser. Its energy and temporal characteristics are determined. It is found that high-power subnanosecond pulses may be obtained from an input pulse of several nanoseconds duration by cutting its leading edge with an STBS mirror and then sharpening it during the amplification process. Calculations are also made of the propagation of a Stokes pulse wth a steep leading edge through a passive switch.

The importance of the pulse shape for the laser-beam target interaction

Abstract: Theoretical analysis of a pulsed CO2 laser beam aluminum target interaction demonstrates increased efficiency if the main laser pulse is preceded by a pulse of enough power to induce breakdown in air and create plasma in front of the metal target surface.

Technique for amplifying two or more laser beams in a single laser amplifier

Abstract: Multiple input laser pulses, wherein each pulse serves to create the population inversion for the next pulse, are amplified in the laser medium of a single laser amplifier apparatus.