Abstract: The disclosure provides an optical system which allows fluctuations in the pulse duration of ultrashort laser pulses to be detected quickly, sensitively and simply, and in a manner which makes it possible to derive an error signal for controlling the pulse duration from the detection. The optical system provided has a laser source (1) designed for generating pulsed laser radiation consisting of a chronological sequence of laser pulses, at least one dispersive optical element (4), designed to impress a group transit time dispersion and thus a chirp on the laser pulses, a nonlinear medium (5) designed for the non-linear spectral broadening of the laser pulses during propagation through the medium (5), and a detection device (6) designed to detect the spectral broadening. Furthermore, the disclosure relates to a method for generating laser pulses.

Abstract: The invention relates to an optical system comprising: a laser source which generates pulsed laser radiation consisting of a temporal sequence of laser pulses; and at least one pulse compression device which is located in the beam path and has a non-linear medium, wherein the laser pulses undergo non-linear spectral broadening during propagation through the medium, and a chirp is applied to the laser pulses. The aim of the invention is to provide an optical system which makes it possible to generate non-linearly compressed laser pulses with improved temporal pulse contrast or with improved pulse quality. According to the disclosed approach, a group delay dispersion which varies along the beam path and which compensates at least partially for the chirp is applied to the laser pulses by the pulse compression device.

Abstract: The disclosure relates to an optical system comprising a laser source (1) which generates pulsed laser radiation consisting of a temporal sequence of laser pulses in an input laser beam (EL), a splitting element (2) which follows the laser source (1) in the course of the beam and splits each of the laser pulses into laser pulse replicas separated spatially and/or temporally from one another, a combination element (4) which follows the splitting element (2) in the course of the beam and superimposes the laser pulse replicas in a respective laser pulse in an output laser beam. It is the task of the disclosure to provide an improved optical system compared to the prior art. It should be possible to generate particularly short and thus spectrally broadband laser pulses of high power with the optical system.

Abstract: A method of propagating a laser signal through an optical waveguide and a waveguide laser system provide a novel way of stabilizing the beam emitted by a fiber laser system above the mode instability threshold wherein the beat length of two or more interfering transverse modes of the laser signal in the optical waveguide is modulated in time.

Abstract: An optical arrangement and a method for producing a combined beam of a plurality of laser light sources are described. In an embodiment, an optical arrangement includes a linear arrangement of a plurality of laser light sources aligned in parallel and having wavelengths different from each other, wherein the laser light sources are disposed in a plurality of groups, a collimation lens for producing a partial beam bundle for each group of laser light sources and a first diffraction grating onto which the partial beam bundles of the groups of laser light sources impinge adjacent to one another, following the collimation lenses, wherein the first diffraction grating is configured to deflect the partial beam bundles onto a second diffraction grating, and wherein the second diffraction grating is configured to deflect the partial beam bundles such that the bundles are combined into an overall beam bundle.

Abstract: A method of propagating a laser signal through an optical waveguide and a waveguide laser system provide a novel way of stabilizing the beam emitted by a fiber laser system above the mode instability threshold wherein the beat length of two or more interfering transverse modes of the laser signal in the optical waveguide is modulated in time.

Abstract: The invention relates to a method and corresponding devices for reducing mode instability in an optical waveguide (1), a light signal becoming unstable in the optical waveguide (1) beyond an output power threshold and energy being transformed from a basic mode into higher order modes. The invention proposes a reduction in temperature variation (2) along the optical waveguide (1) and/or a reduction in changes in the optical waveguide (1) that are caused by spatial temperature variation as a result of mode interference.

Abstract: The invention relates to a double-sheath fiber having a core region (1) and a sheath region, the sheath region having an inner region (2) and an outer region (3), which comprises a refractive index that is lower with respect to that of the inner region (2) and the core region (1), wherein the outer region (3) surrounds the inner region (2). The invention proposes an internal structure (4) of the inner region (2) which effects a spatial overlap of modes of higher order with the core region (1), which is lower than the spatial overlap of a fundamental mode with the core region (1).

Abstract: The invention relates to a method and corresponding devices for reducing mode instability in an optical waveguide (1), a light signal becoming unstable in the optical waveguide (1) beyond an output power threshold and energy being transformed from a basic mode into higher order modes. The invention proposes a reduction in temperature variation (2) along the optical waveguide (1) and/or a reduction in changes in the optical waveguide (1) that are caused by spatial temperature variation as a result of mode interference.

Abstract: The invention relates to a transverse mode filter in an optical waveguide (3). The aim of the invention is to produce a transverse mode filter that permits a monolithic construction of a laser in a multi-mode waveguide. To achieve this, according to the invention the filter comprises a Fabry-Perot cavity integrated into the optical waveguide (3) and comprising two reflective elements (5) situated at a distance from one another. In addition, the waveguide (3) is modified in the region of the Fabry-Perot cavity and/or in the region of the reflective elements (5) in relation to the remaining regions of the waveguide with respect to the effective refractive index of at least one mode of the waveguide.

Abstract: The invention relates to a double-sheath fiber having a core region (1) and a sheath region, the sheath region having an inner region (2) and an outer region (3), which comprises a refractive index that is lower with respect to that of the inner region (2) and the core region (1), wherein the outer region (3) surrounds the inner region (2). The invention proposes an internal structure (4) of the inner region (2) which effects a spatial overlap of modes of higher order with the core region (1), which is lower than the spatial overlap of a fundamental mode with the core region (1).

Abstract: The invention relates to a transverse mode filter in an optical waveguide (3). The aim of the invention is to produce a transverse mode filter that permits a monolithic construction of a laser in a multi-mode waveguide. To achieve this, according to the invention the filter comprises a Fabry-Perot cavity integrated into the optical waveguide (3) and comprising two reflective elements (5) situated at a distance from one another. In addition, the waveguide (3) is modified in the region of the Fabry-Perot cavity and/or in the region of the reflective elements (5) in relation to the remaining regions of the waveguide with respect to the effective refractive index of at least one mode of the waveguide.