An apparatus includes at least one Raman medium configured to receive a pump beam and shift at least a portion of the pump beam into a Stokes-shifted output beam. The apparatus also includes a first lens configured to receive and focus the pump beam into the at least one Raman medium. The apparatus further includes first and second retro-lens assemblies, each including at least one prism configured to reflect beams from the at least one Raman medium back into the at least one Raman medium and multiple second lenses configured to control optical propagation of the beams entering and exiting the at least one Raman medium. Multiple pairs of lenses form multiple confocal arrangements of lenses. The pairs of lenses include the first lens and the second lenses of the retro-lens assemblies. The at least one Raman medium is optically positioned between the lenses in the confocal arrangements of lenses.

A fluid-cooled laser amplifier module (100) is disclosed which comprises: a casing; a plurality of slabs (110) of optical gain medium oriented in parallel in the casing for cooling by a fluid stream (154, 156); a polarisation rotator (120) disposed between a first group of one or more slabs (111) of the optical gain medium and a second group of one or more slabs (112) of the optical gain medium; optical windows (150, 152) for receiving an input beam or pulse (130) for amplifying by the slabs and for outputting the amplified beam or pulse (140); and fluid stream ports (155, 157) for receiving and discharging the fluid stream for cooling the slabs.

A multipass laser amplifier includes a mirror, a mirror device, a gain crystal, and refractive or diffractive beam-steering element. The gain crystal is positioned on a longitudinal axis of the multipass laser amplifier between the mirror and the mirror device. The beam-steering element is positioned on the longitudinal axis between the gain crystal and the mirror device. The beam-steering element has no optical power and deflects a laser beam, by refraction or diffraction, for each of multiple passes of the laser beam between the first mirror and the mirror device, such that each pass goes through the gain crystal for amplification of the laser beam and goes through a different respective off-axis portion of the beam-steering element. The no optical power of the beam-steering element enables maintaining a large beam size in the gain crystal, thereby facilitating amplification to high average power.

A laser system includes: A. a solid-state laser apparatus configured to output a pulse laser beam having light intensity distribution in a Gaussian shape that is rotationally symmetric about an optical path axis; B. an amplifier including a pair of discharge electrodes and configured to amplify the pulse laser beam in a discharge space between the pair of discharge electrodes; and C. a conversion optical system configured to convert the light intensity distribution of the pulse laser beam output from the amplifier into a top hat shape in each of a discharge direction of the pair of discharge electrodes and a direction orthogonal to the discharge direction.

An ultraviolet laser apparatus includes an oscillation-stage laser, an amplifier that amplifies the pulse laser light, and an optical isolator. The optical isolator includes a first Faraday rotator that rotates the polarization direction of the pulse laser light output from the oscillation-stage laser by a first angle in a first rotation direction, a first polarizer so disposed to transmit the pulse laser light that exits out of the first Faraday rotator at normalized transmittance greater than or equal to 0.9, a second Faraday rotator that rotates the polarization direction of the pulse laser light passing through the first polarizer by a second angle in the opposite direction to the first rotation direction, and a second polarizer so disposed to transmit the pulse laser light that exits out of the second Faraday rotator at the normalized transmittance greater than or equal to 0.9.

A planar waveguide amplifier includes a planar waveguide including a flat plate-like core; a first cladding provided on a first principal face of the core; and a second cladding provided on a second principal face of the core, and signal light and pumping light travel into the planar waveguide so that the signal light and the pumping light propagate inside the core in such a manner that optical paths of the signal light and the pumping light overlap each other, and in a zig-zag manner, and the core is an amplification medium containing a rare-earth element serving as an active ion of a three-level system, and absorbs the signal light on the basis of a reduction in intensity of the pumping light.

An apparatus includes at least one Raman medium configured to receive a pump beam and shift at least a portion of the pump beam into a Stokes-shifted output beam. The apparatus also includes a first lens configured to receive and focus the pump beam into the at least one Raman medium. The apparatus further includes first and second retro-lens assemblies, each including at least one prism configured to reflect beams from the at least one Raman medium back into the at least one Raman medium and multiple second lenses configured to control optical propagation of the beams entering and exiting the at least one Raman medium. Multiple pairs of lenses form multiple confocal arrangements of lenses. The pairs of lenses include the first lens and the second lenses of the retro-lens assemblies. The at least one Raman medium is optically positioned between the lenses in the confocal arrangements of lenses.

A resonating optical amplifier includes a laser pump cavity defined by a first mirror and a second mirror with a laser pump gain medium configured within a first portion of the laser pump cavity and a Raman amplifier within a second portion of the laser pump cavity. A circulating pump-laser light is introduced to the laser pump gain medium forming a pump signal that is configured to bi-directionally propagate along a beam path within the laser pump cavity. The Raman amplifier is positioned in line with the beam path of the pump signal and operable to impart gain on a seed pulse. The seed pulse and the pump signal are co-aligned and linearly polarized.

A gas laser device includes a shielding plate that is a first shielding member, and a shielding plate that is a second shielding member. The first shielding member includes a first opening, and a second opening. A laser beam that is to be propagated to discharge regions passes through the first opening. The laser beam that has taken a round trip through the discharge regions after passing through the first opening passes through the second opening. The second shielding plate faces the first shielding member the discharge regions located therebetween. The shielding plate includes an opening that is a third opening. The laser beam that has been propagated through the first opening and the discharge regions, and the laser beam that is to be propagated to the second opening through the discharge regions pass through the third opening. A plane shape of the third opening includes a rectilinear segment.

Disclosed are optical arrangements including: a disk-shaped laser-active medium, a deflecting device, having a plurality of mirror elements on which mirror faces for deflecting a laser beam are formed, and having a base body on which the mirror elements are fastened, the mirror faces of the mirror elements being oriented in such a way that the laser beam is deflected by a respective mirror face via the disk-shaped laser-active medium to another mirror face. The mirror elements are formed in one piece or are monolithically joined, and have a connecting section that is formed rotationally symmetrically with respect to a center axis and is rigidly connected by a material-fit connection or a direct connection to the base body.