Abstract: Disclosed are methods and apparatus for generating a sub-208 nm laser. A laser apparatus includes one or more seed radiation sources for generating a first radiation beam having a first fundamental wavelength on a first optical path and a second radiation beam having a second fundamental wavelength on a second optical path, a first amplifier for amplifying the first radiation beam, a second amplifier for amplifying the second radiation beam, and a wavelength conversion module comprising a plurality of crystals for frequency multiplying and mixing the amplified first and second radiation beams to produce an output beam at a fifth harmonic that is less than about 208 nm.

Abstract: An aerated swirling vertical shaft with double volute chambers comprises an upper volute chamber (2) and a first shrinking section (3) beneath the upper volute chamber (2), a venting passage (4) outside the upper volute chamber (2), a vertical shaft section (7) beneath the first shrinking section (3), as well as an aerated lower volute chamber (5) and a second shrinking section (6) communicated with the aerated lower volute chamber (5) between the first shrinking section (3) and the vertical shaft section (7), wherein the upper end of the aerated lower volute chamber (5) is connected with the first shrinking section (3), the lower end of the second shrinking section (6) is connected with the vertical shaft section (7); the upper end of the venting passage (4) is communicated with the atmosphere and the lower end is communicated with the aerated lower volute chamber (5).

Abstract: An aerated swirling vertical shaft with double volute chambers comprises an upper volute chamber (2) and a first shrinking section (3) beneath the upper volute chamber (2), a venting passage (4) outside the upper volute chamber (2), a vertical shaft section (7) beneath the first shrinking section (3), as well as an aerated lower volute chamber (5) and a second shrinking section (6) communicated with the aerated lower volute chamber (5) between the first shrinking section (3) and the vertical shaft section (7), wherein the upper end of the aerated lower volute chamber (5) is connected with the first shrinking section (3), the lower end of the second shrinking section (6) is connected with the vertical shaft section (7); the upper end of the venting passage (4) is communicated with the atmosphere and the lower end is communicated with the aerated lower volute chamber (5).

Abstract: A gas discharge laser system producing a laser output pulse and a method of operating such a system is disclosed which may comprise a pulse stretcher which may comprise a laser output pulse optical delay initiating optic directing a portion of the laser output pulse along a laser system output pulse optical axis and diverting a portion of the output pulse into an optical delay having an optical delay path and which may comprise a plurality of confocal resonators in series aligned to deliver an output of the optical delay to the laser output pulse optical delay initiating optic; an optical axis alignment mechanism comprising an radial mirror positioning mechanism operable to position the output of the optical delay to the align with the portion of the laser output pulse transmitted along the optical axis of the portion of the laser system output pulse transmitted by the laser output pulse optical delay initiating optic.

Abstract: A gas discharge laser system producing a laser output pulse and a method of operating such a system is disclosed which may comprise a pulse stretcher which may comprise a laser output pulse optical delay initiating optic directing a portion of the laser output pulse along a laser system output pulse optical axis and diverting a portion of the output pulse into an optical delay having an optical delay path and which may comprise a plurality of confocal resonators in series aligned to deliver an output of the optical delay to the laser output pulse optical delay initiating optic; an optical axis alignment mechanism comprising an radial mirror positioning mechanism operable to position the output of the optical delay to the align with the portion of the laser output pulse transmitted along the optical axis of the portion of the laser system output pulse transmitted by the laser output pulse optical delay initiating optic.

Abstract: A diode-pumped laser with a direct edge coupling of a pump beam is provided. The laser includes a microchip laser cavity optically pumped by a laser diode emitting an astigmatic pump beam having a substantially elliptical beam cross-section at an output laser diode facet. The microchip laser cavity is disposed at a substantial distance exceeding 0.001? from the laser diode pump where the astigmatic pump beam has a greatly reduced ellipticity, providing high laser output efficiency without coupling lens element between the laser cavity and the laser diode pump. The pumping arrangement is favourable for single-mode lasing. In some embodiments, the laser cavity includes nonlinear crystal for intra-cavity SHG, a saturable absorber for passive Q-switching and mode locking, and a polarizing prism.

Abstract: A diode-pumped laser with a direct edge coupling of a pump beam is provided. The laser includes a microchip laser cavity optically pumped by a laser diode emitting an astigmatic pump beam having a substantially elliptical beam cross-section at an output laser diode facet. The microchip laser cavity is disposed at a substantial distance exceeding 0.001? from the laser diode pump where the astigmatic pump beam has a greatly reduced ellipticity, providing high laser output efficiency without coupling lens element between the laser cavity and the laser diode pump. The pumping arrangement is favourable for single-mode lasing. In some embodiments, the laser cavity includes nonlinear crystal for intra-cavity SHG, a saturable absorber for passive Q-switching and mode locking, and a polarizing prism.

Abstract: A truncated series-based cavity interferometer contains a multi-reflection cavity upon which an input light beam is directed at an acute angle, to produce a spatially spread series of multiple order beams through which the transfer function (e.g., a generally square pass/stop profile) of the interferometer is defined. Because the input beam is incident upon the cavity at an acute angle, it is non counter-propagating with respect to the reflected beam, so that no circulator is required for beam separation. The intensity profile of the energy contained in the composite set of spatially separated multiple order beams comprises a spatially separated decaying series of reflections, that are intercepted by independently positionable spatial filter elements.

Abstract: A tunable etalon for use in a dispersion compensator according to the present invention includes a Gires-Tournois (GT) etalon with a variably reflective front mirror section and a fixed back mirror section defining a resonance cavity therebetween. The front mirror section includes one or more tunable gaps formed between pairs of partially reflective mirrors and filled with a material with a variable index of refraction, e.g. liquid crystal. Due to the variability of the material's refractive index, the reflectivity of the tunable cavity can be adjusted by inducing an electric field using a controllable voltage source. With such a variable reflectivity, the time (group) delay among frequency components of input light can be adjusted and varied within a range of a few milliseconds or less, such that chromatic dispersion can be tuned dynamically. A pair of such etalons, which have equal and opposite dispersion curves, can achieve a wide flat range of dispersion.

Abstract: An add/drop device is described that allows channels from a multi-channel optical path to be dropped to a device and a new or modified channel to be added to the multi-channel optical path. The device thereby has access to a channel from the multi-channel optical path without having access to all of the channels. In one embodiment, the add/drop device of the invention includes one or more intermediate ports and a switch. The intermediate ports communicate the channels not dropped by the add/drop device and the switch selectively optically couples the dropped channel either to the device or to be added back into the multi-channel path. The switch also selectively optically couples the new or modified channel to be added to the multi-channel path. The one or more intermediate ports allow multiple add/drop devices to be optically coupled together to provide a configurable add/drop mechanism.