31 Mar 2003
The pick of this week's patent applications including a mid-infrared-emitting microchip laser.
• Title: Multi-wavelength laser apparatus and method
Applicant: Multiwave Networks, US
International application number: WO 03/026083
A laser capable of simultaneously emitting multiple wavelengths is described in application WO 03/026083. Crucially, the inventors say their source can emit multiple wavelengths on the International Telecommunication Union's standard grid.
The device uses a diode-pumped, rare-earth doped fiber amplifier as the gain medium. Two filters, a periodic filter followed by a resonant filter, then define a set of ITU wavelengths. The system is enclosed within a ring resonator, which the inventors say can be made with polarization-maintaining fiber.
"The resonator may also comprise in-line optical isolators to ensure unidirectional operation and eliminate undesired reflections," say the authors. "It may also be designed to operate in a set of single cavity longitudinal modes."
• Title: Apparatus with ultraviolet spectrum lamp for the treatment of psoriasis
Applicant: El.En S.P.A, Italy
International application number: WO 03/024526
The UV-emitting lamp described in application WO 03/024526 could soon be used to treat psoriasis, according to the authors of the patent. The instrument uses a dielectric-discharge excimer lamp, which the authors say has a well-defined peak at 308 nm. The lamp itself is mounted on a hinged or manoeuvrable arm and is supported by a stand.
• Title: Mid-IR microchip laser: ZnS:Cr2+ laser with saturable absorber material
Applicant: University of Alabama at Birmingham Research Foundation
International application number: WO 03/02086
Patent application WO 03/026086 describes how to fabricate a mid-IR-emitting microchip laser based on ZnS. The method relies on introducing a thin-film of a transition metal such as chromium into the laser's ZnS facets. The inventors say that thermal annealing ensures the chromium dopant diffuses uniformly throughout the crystal.
The laser is then formed in one of two ways: either by direct deposition of mirrors onto the facets of the Cr2+:ZnS wafer or by relying on internal reflectance within the facets. According to the patent, the device can be pumped directly by a diode or by a fiber laser. The patent also discusses various applications of such as source.
• Title: Discharge source with gas curtain for protecting optics from particles
Applicant: EUV Limited Liability Corporation, US
International application number: WO 03/026363
Is dust and debris hampering your photolithography system's performance? If so, then the device described in application WO 03/026363 is one to look out for. The so-called "gas curtain device" projects a stream of gas perpendicular to the laser source being used. This deflects the debris particles and prevents build-up on the optics used in photolithography.
Jacqueline Hewett is news reporter on Optics.org and Opto & Laser Europe magazine.