Abstract: An optical assembly reduces a spectral bandwidth of an output beam of a laser. The assembly includes a beam-expanding optical unit within a laser resonator. The latter serves to increase a beam cross section of a resonator-internal laser beam in at least one expansion cross-sectional dimension such that at least one resonator-internal expansion laser beam section arises. The assembly also includes an optical grating in a retroreflective arrangement for the resonator-internal laser beam. A beam-limiting stop acts in the expansion cross-sectional dimension and is arranged in the beam path of the expansion laser beam section. This yields an optical assembly in which unwanted thermal effects on account of optical components of the optical assembly heating during laser operation due to a local power density of the resonator-internal laser beam are reduced or avoided.

Abstract: An optical assembly reduces a spectral bandwidth of an output beam of a laser. The assembly includes a beam-expanding optical unit within a laser resonator. The latter serves to increase a beam cross section of a resonator-internal laser beam in at least one expansion cross-sectional dimension such that at least one resonator-internal expansion laser beam section arises. The assembly also includes an optical grating in a retroreflective arrangement for the resonator-internal laser beam. A beam-limiting stop acts in the expansion cross-sectional dimension and is arranged in the beam path of the expansion laser beam section. This yields an optical assembly in which unwanted thermal effects on account of optical components of the optical assembly heating during laser operation due to a local power density of the resonator-internal laser beam are reduced or avoided.

Abstract: The disclosure provides a bandwidth narrowing module for setting a spectral bandwidth of a laser beam of a laser light source. The bandwidth narrowing module includes a beam expanding module for expanding a laser beam transversely with respect to a propagation direction of the laser beam and comprising a reflection grating. A first optical component of the bandwidth narrowing module is configured so that a disturbance with a cylindrical portion about a first axis transversely with respect to an optical axis of the bandwidth narrowing module can be impressed on a wavefront of a laser beam. The first optical component is embodied such that it is pivotable about a pivoting axis parallel to the first axis.

Abstract: The invention relates to a process for producing photonic crystals by first providing an inorganic photoresist which, on illumination with energy greater than the electronic band gap of the photoresist, exhibits a phase alteration. Illumination of the photoresist with a laser beam whose energy is lower than the electronic band gap of the photoresist but whose intensity at the focal point is so high that nonlinear effects occur there nevertheless results in a phase alteration in the photoresist. Thereafter, the illuminated photoresist is exposed to an etching solution which preferentially dissolves one phase of the photoresist, and the developed photoresist is finally removed therefrom as a photonic crystal. Inorganic photonic crystals produced by the process according to the invention are suitable for completely optical systems, circuits and components for optical telecommunication or computer systems.

Abstract: The invention relates to a process for producing photonic crystals by first providing an inorganic photoresist which, on illumination with energy greater than the electronic band gap of the photoresist, exhibits a phase alteration. Illumination of the photoresist with a laser beam whose energy is lower than the electronic band gap of the photoresist but whose intensity at the focal point is so high that nonlinear effects occur there nevertheless results in a phase alteration in the photoresist. Thereafter, the illuminated photoresist is exposed to an etching solution which preferentially dissolves one phase of the photoresist, and the developed photoresist is finally removed therefrom as a photonic crystal. Inorganic photonic crystals produced by the process according to the invention are suitable for completely optical systems, circuits and components for optical telecommunication or computer systems.

Abstract: The invention relates to a process for producing a three-dimensional photonic crystal which consists of a material with high refractive index. To this end, a photonic crystal which consists of a polymer is first provided, through whose surface there are empty interstitial sites. As a result of introduction of a filler into the interstitial sites, a network forms there from the filler. After the removal of the polymer, cavities form in the network formed from the filler, into which the material with high refractive index is introduced, so that a structure of the material with high refractive index forms therein. After the removal of the filler, the structure of the material with high refractive index remains, which can be removed as the photonic crystal which consists of a material with high refractive index. Photonic crystals produced by the process according to the invention have complete band gaps in the region of telecommunications wavelengths.