19 Feb 2003
The pick of this week's patent applications including a wavelength-tunable ring laser.
• Title: Photonic buoy
Applicant: Raytheon, US
International application number: WO 03/012469
Buoys typically guide ships through dangerous waters, but that's not the case in patent application WO 03/012469. Raytheon's photonic buoy, which is attached to a length of cable, relays a panoramic view of the horizon to a remote location. Underneath the water, the cable is attached to an "optical bench" on the top of a vessel's hull, which is used to gather and transmit the video signals.
• Title: High density fibre coupling
Applicant: Nanyang Technological University, Singapore
International application number: WO 03/012512
Patent application WO 03/012512 details a method for aligning a large number of optical fibers on a photonic integrated circuit (PIC). A PIC is a layered structure typically comprising a planar optical device, such as a waveguide or VCSEL, mounted on a substrate.
To couple the light into a fiber, the inventors etch ports into a fiber-guiding layer that covers the optical device. A mirror or Bragg grating can also be included in the port to redirect the incoming light into the fiber. The authors say that an important advantage of this design is that it eliminates the need for waveguides to be routed to the edge of the chip. It also allows fibers to be passively aligned.
• Title: Wavelength tunable ring laser
Applicant: Binoptics Corporation, US
International application number: WO 03/012370
This application details a semiconductor ring laser, which has an output wavelength that can be tuned by varying a voltage. The upper surface of the laser cavity is metal-coated, which provides a contact for applying the voltage. This coating is divided into at least two segments that act as electrodes. "Variations in the voltage applied to the two electrodes allows tuning of the laser output wavelength," say the authors in their application.
• Title: Fingerprint imaging device
Applicant: Identix Incorporated, US
International application number: WO 03/012729
A US company has come up with an optical device for recording fingerprints. The device comprises a transparent plate for placing the finger on, a light source to illuminate the finger and an imaging system. To minimize the thickness of the transparent plate, the authors say it should have a refractive index less than 1.49.
Jacqueline Hewett is news reporter on Optics.org and Opto & Laser Europe magazine.