19 Nov 2004
The pick of this week's patent applications including a photonic crystal laser for chemical detection.
• Title: Photonic crystal laser sources for chemical detection
Applicant: California Institute of Technology, US
International application number: WO 2004/100327
The authors of patent application WO 2004/100327 discuss the detection of chemicals using photonic crystal lasers. In their setup, the sample is placed directly into the photonic crystal cavity and specifically within the lasing mode. The inventors say this allows them to perform high-resolution spectroscopy with single-molecule sensitivity on femtoliter volumes of analyte. "The [photonic crystal] cavity is pumped and an emission from the laser is used to detect the presence of the chemical in the analyte," explain the authors.
• Title: Eye-safe solid state laser system
Applicant: Raytheon Company, US
International application number: WO 2004/100330
Raytheon has applied to patent an eye-safe laser. In the first stage of the two-stage design, either a neodymium or ytterbium-ion doped crystal is pumped with the output from an infrared diode array bar. This emission is then used to intracavity pump an erbium-ion-doped crystal which emits in the eye-safe region of 1.4 to 1.8 microns. According to the inventors, the laser is inherently compact and low-cost and its output power can be scaled by changing the number of diode pump sources. "The intra-cavity pump scheme of appropriate erbium crystals also provides efficient generation of ultrashort Q-switched pulse operation of such lasers," conclude the authors.
• Title: UV light source coated with nano-particles of phosphor
Applicant: Philips Intellectual Property & Standards GmbH, Germany
International application number: WO 2004/099664
Scientists at Philips have come up with a way to make a transparent light source comprising an optical waveguide plate and a UV light source. Light is coupled in at the edges of the waveguide plate and distributed within the sheet by total internal reflection. The plate is covered with a layer of phosphor nano-particles that convert UV light from 300 to 400 nm into visible light from 420 to 480 nm. Light is coupled out via scattering from the particles. "If the size of the particles, the refractive index and the thickness of the layer are correctly selected, optical transparency can be achieved," state the authors in their application. They add that the covering layer has a thickness from 10 to 5000 nm and a reflection of greater than 20%.