Max-planck-gesellschaft Zur F&#xf6;rderung Der Wissenschaften E. V.

Fritz P Schafer

Zsolt Bor

Michael Stuke

Sandor Szatmari

Krassimir Stankov

Wolfgang Luttke

Mode-locked laser comprising an active medium for the emission of a fundatal frequency radiation w1, with a resonator which is defined by a first mirror and a second mirror and in which the active medium is disposed, and a nonlinear optical means which is arranged between the active medium and the second mirror and which in combination with the second mirror effects a preferred reflection of radiation of higher intensity compared with radiation of lower intensity and it converts a fundamental-frequency radiation reversibly into radiation of a first frequency and radiation of a second frequency in such a manner that with increasing intensity the fraction of the radiation of the second frequency increases, and that the second mirror reflects at the second frequency to a greater extent than at the first frequency. A further development of said laser comprises a means for coupling laser radiation of a further frequency w2 into the nonlinear means and a reflector arrangement which is arranged in the path of radiation emerging from the nonlinear means and for the fundamental-frequency radiation w1 and the radiation of the other frequency has a lower reflectivity than for radiation (w1+w2; w1-w2) which arises by interaction of the two laser radiations in the nonlinear means. In this manner a simple synchronization of the mode-locked laser with the coupled-in laser radiation is possible. The coupled-in laser can originate from a second laser medium which is arranged in a second resonator which has a part in common with the first resonator.

Mode-locked laser

An optical interferometric apparatus in which the intensity transmission factor is electrically controllable between at least one radiation beam input and at least one radiation beam output includes an interferometric device with a beam splitter for producing two coherent partial beams which pass via corresponding partial beam paths to a beam combining device where they interfere. In at least one of the partial beam paths there is disposed an electro-optical device in which the optical length of the portion of the partial beam path in question passing through it is electrically changeable, e.g., by means of the refractive index. The partial beams are combined strictly parallel with each other, so that the output beam provided by the beam combining device has a constant phase across its width and the intensity can be varied essentially between the full intensity of the input beam and zero by an appropriate change of the optical path length.

Optical interferometric apparatus with an electrically controllable

A radial or tangential polarization of a beam of light radiation with respect to an optical axis, along which said beam propagates, is effected by causing interaction of the beam with at least one conical interface between a pair of optical media having different indices of refraction. The conical interface(s) may be provided with a polarization-selective coating.

Method and device for polarizing light radiation

An optical laser pumping system comprises means for providing a highly collimated pump radiation beam propagating along an axis, and an optical element which forms a concave, frustro-conical reflecting surface which is coaxial to said axis and tapers in the direction of beam propagation from an entrance end of large cross section, into which said beam enters, to a distal end of small cross section which surrounds said axis in spaced relationship. The laser medium is positioned between said ends along said axis.

Optical laser pumping system

A method of producing individual short laser pulses in which a stimulatable laser medium is excited by a pump pulse in order to produce a population inversion above a laser threshold value, the population inversion being kept below the threshold value after emission of the short radiation pulse. The laser medium is common to two resonators and from it energy in the form of the desired individual short laser radiation pulse is first taken from the first resonator by means of a first relaxation process of given threshold value, relatively short time constant and relatively low quality factor, after which the inversion in the laser medium is kept below the preset threshold value of the first resonance process by a second relaxation process of relatively long time constant and relatively high quality factor in the second resonator coupled to the first. The resulting individual short laser radiation pulse can be supplied as pump pulse to a distributed feedback dye (DFB) laser at an intensity relative to the DFB laser medium threshold such that the DFB laser emits at least one ultra-short radiation pulse.

Method and device for producing individual short laser pulses

In a method and an apparatus for generating a hot plasma which emits elecmagnetic radiation in the wavelength range below about 100 nm in a predetermined volume, in which a laser radiation pulse of short duration with sufficient energy and power density is focused into the volume containing a target material, the laser radiation energy which is necessary for generating the plasma emitting the radiation is radiated into the target volume by a focused laser radiation pulse which is shorter than one picosecond. The method may be used in ASE X-ray laser comprising an axicon focusing optics.

Method and apparatus for generating short intensive pulses of

Ultra-short individual laser pulses, having a half-amplitude duration of 100 picoseconds or less and a recurrence frequency of one Hz to one mHz are generated in a self Q-switching distributed feedback dye laser that employs a high density diffraction grating as a beam divider, dividing a primary beam from a pulsed pump laser into two excitation beams of +1 and -1 order; the excitation beams are directed, by two reversing mirrors, to impinge upon a focal line in a dye solution serving as an active laser medium. The pulses of the primary beam have a half-amplitude duration many times greater than 100 psec but no greater than 20 nsec, and the beam intensity is such that the stimulation of the dye does not exceed its laser threshold by more than 20%.

Method and apparatus for generating ultra-short individual laser pulses

A method of photochemical separation of isotopes, wherein molecules containing differing isotopes to be separated are selectively excited by laser radiation, and the excited molecules are collectively reacted with a scavenger which is relatively inert to molecules of lesser excitation, the reaction producing a stable addition product which is readily isolatable.

Method of photochemical separation of isotopes

A display process for the optical presentation of information which process omprises impinging laser beams modulated as to their direction, intensity and/or frequency, upon a transparent target containing a fluorescent substance which is excited by said laser beams to optical fluorescence, e.g., which absorbs in the ultraviolet range and yields fluorescent radiation in the visible range; typical ions capable of fluorescence are uranyl ions or ions of the rare earth elements.

Process for the optical display of information using lasers

Novel dyestuffs comprising at least one laser dyestuff radical and at least one fluorescent dyestuff radical, where the fluorescent range of the fluorescent dyestuff radical overlaps the absorption range of the laser dyestuff radical and is linked with the laser dyestuff radical directly or via a bridge member having a length of at most 20 A in such a manner that the .pi. electron systems of the individual radicals are decoupled, are outstandingly effective and long lived when used in dyestuff lasers. The dyestuffs can be of the formula:

Laser dyes comprising fluorescent and laser dyestuff residues

To permit high density of light output, for example in the order of 400kW.sup.3 required to stimulate lasers, the arc is stabilized by generating the arc inside a transparent tube, the inner surface of which is covered with a film of liquid, such as water, or an aqueous metal salt solution, the liquid being supplied through one electrode secured in a rotatable holder to which the tube is attached, to a rotatable receiver holder in which the other electrode is located, the liquid then draining away. Rapid rotation of the tube adheres the liquid by centrifugal force to the inner surfaces of the tube.

Electric arc discharge lamp

The cell of a liquid laser is defined between the rounded, parallel edges four coaxial cylinder sectors of fused quartz. The narrow gaps circumferentially bounded by the flat, converging side faces of the sectors provide conduits for rapid flow of dye liquid into and out of the cell which extend over the full axial length of the cell. The light of a flash tube is directed toward the cell through the cylindrically arcuate outer face of each sector.

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Gottingen-Nikolausberg, Germany

Fritz P Schafer