15 Apr 2003
The pick of this week's patent applications including holey-fiber based optical devices that make use of the Raman effect.
• Title: Optical fibre-based devices utilising the Raman effect
Applicant: University of Southampton, UK
International application number: WO 03/029851
Patent application WO 03/039851 describes how Raman scattering within a holey-fiber can be used to make optical amplifiers or modulators. Light at a predetermined wavelength is fired at the holey fiber. Raman scattering occurs in the fiber and alters the wavelength of the light emitted.
"For optical gain, the second [output] wavelength is longer than the first [input] wavelength, and the device can be operated as an amplifier, or a laser if optical feedback is provided," say the authors. The device can be used as a modulator when the output wavelength is shorter than the input wavelength. According to the authors, the fiber can be doped to tailor properties such as its gain spectrum, bandwidth, power handling and mode propagation.
• Title: Polarization preserving optical fiber and absolute single polarization optical fiber
Applicant: Nippon Telegraph and Telephone Corporation, Japan
International application number: WO 03/029854
NTT of Japan is trying to patent an optical fiber that it says preserves the polarization of the transmitted light over long distances. The authors say this is made possible by using a photonic-crystal cladding structure that is designed in four quadrants. The design includes a pair of larger holes fabricated next to the core and in opposing quadrants.
• Title: Liquid crystal display with reduced flicker
Applicant: Koninklijke Philips Electronics, the Netherlands
International application number: WO 03/030135
Patent application WO 03/030135 outlines a method to reduce the flicker of liquid-crystal displays. The approach uses correction circuitry to modulate the light beam containing the image information. "In alternating even and odd numbered frames, a light beam is modulated using complementary voltages relative to a common electrode," say the inventors.
• Title: Apparatus and method for real-time IR spectroscopy
Applicant: University of Delaware, US
International application number: WO 03/029769
Patent application WO 03/029769 details a method to gathering infrared spectral information that requires no moving parts or Fourier transform analysis. The apparatus required includes an infrared light source, an optically dispersive element and a focal plane array to detect the dispersed light. Fiber-optic coupling allows remote sensing and adds to the instrument's portability and reliability. The inventors say their system suits many industrial and environmental applications and can also be used to sense chemical and biological warfare agents in real time.
Jacqueline Hewett is news reporter on Optics.org and Opto & Laser Europe magazine.