Patents by Inventor Ashok Balakrishnan

Ashok Balakrishnan has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Publication number: 20060119945
    Abstract: Diffraction gratings are formed from grooves each having a reflective facet and a non-reflective facet. The net reflection of TE (Transverse Electric) and TM (Transverse Magnetic) polarizations from the grating structure is traded off against the polarization dependent reflection, by controlling the degree of metallization of the reflective facet and by ensuring that there is no metallization of non-reflective sidewalls. other diffraction gratings are manufactured from trenches etched perpendicular to a waveguide. The trenches are metallized and back-filled with a filling material having a refractive index matched to that of the waveguide. The gratings essentially have no non-reflecting sidewalls with insignificant polarization influence from side walls.
    Type: Application
    Filed: August 26, 2003
    Publication date: June 8, 2006
    Inventors: Ashok Balakrishnan, Kokou Dossou, Muthukumaran Packirisamy
  • Publication number: 20050219701
    Abstract: The invention relates to a planar waveguide reflective diffraction grating for use in an optical device, such as a wavelength division multiplexer, providing an increased bandwidth over conventional planar waveguide reflection diffraction gratings while eliminating the polarization dependent loss (PDL) typically associated therewith. The multiplexer/demultiplexer according to the present invention includes input and output ports optimally positioned in accordance with the grating facet diffraction envelope to minimized back reflection to the input ports and maximize output light collected from different diffraction orders.
    Type: Application
    Filed: June 3, 2005
    Publication date: October 6, 2005
    Inventors: Ashok Balakrishnan, Serge Bidnyk, Matt Pearson
  • Publication number: 20050213886
    Abstract: The invention relates to a double-grating subtractive-dispersion optical channel multiplexer/demultiplexer for combining or separating optical channels and providing the output channels with a flat-top response. The FSR of the first grating is substantially equal to the channel spacing of the optical channels, such that the emission from the first grating achieves a cyclic offset of incidence angle into the second grating of the system.
    Type: Application
    Filed: June 1, 2005
    Publication date: September 29, 2005
    Inventors: Ashok Balakrishnan, Serge Bidnyk, Matt Pearson
  • Publication number: 20050213887
    Abstract: The invention relates to a planar lightwave circuit including a two stage optical filter for use in a bi-directional transceiver. A first stage includes a non-dispersive optical filter, which enables light within in a certain wavelength range, e.g. a signal channel from a laser source, to be launched onto an input/output waveguide, while light within another wavelength range, e.g. one or more detector channels, will be directed from the input/output waveguide to a second stage. The second stage includes a reflective diffraction grating with a higher resolution than the first stage providing passbands 2 to 5 times thinner than the first stage.
    Type: Application
    Filed: June 1, 2005
    Publication date: September 29, 2005
    Inventors: Ashok Balakrishnan, Serge Bidnyk, Matt Pearson
  • Publication number: 20050213214
    Abstract: The invention relates to a planar waveguide reflective diffraction grating for use in an optical device, such as a wavelength division multiplexer, providing an increased bandwidth over conventional planar waveguide reflection diffraction gratings while eliminating the polarization dependent loss (PDL) typically associated therewith. Accordingly, a low order (<3), high aspect ratio (>10) grating is provided with a very short side wall (less than the wavelength of the optical signal) for use with incident angles of less than 15°.
    Type: Application
    Filed: October 25, 2004
    Publication date: September 29, 2005
    Inventors: Serge Bidnyk, Ashok Balakrishnan, Matt Pearson
  • Publication number: 20050213888
    Abstract: The invention relates to a planar lightwave circuit including a pair of opposed concave reflective diffraction gratings sharing the same focal line, which separates first and second slab waveguide regions. The ends of input and output waveguides are positioned along the focal line for launching and receiving light directed by one or both of the diffraction gratings. The invention enables light within in a certain wavelength range to be launched from an input waveguide, directed by a single diffraction grating, and output waveguides, all within a single slab waveguide region, while light within another wavelength range will be directed from one diffraction grating to another for output waveguides in a different slab waveguide region.
    Type: Application
    Filed: August 24, 2004
    Publication date: September 29, 2005
    Inventors: Serge Bidnyk, Ashok Balakrishnan, Matt Pearson
  • Publication number: 20050151966
    Abstract: Planar waveguide based grating devices and spectrometers, for species-specific wavelength detection for example, are disclosed. A planar waveguide spectrometer apparatus may have a microfluidic channel or compartment microfabricated integrally with a planar waveguide or hybrid assembled with the planar waveguide and optically coupled thereto. The planar waveguide may also include a thin planar substrate which is made of a transparent waveguiding optical material and has a planar multilayer, one or more input waveguides, a waveguide-based spectrometer, and one or more output waveguides integrally formed thereon. An apparatus which incorporates a planar waveguide, a diffractive construct for diffracting light through the planar waveguide onto a curved image surface, and a plurality of output waveguides emanating from the curved image surface at locations selected to extract predetermined wavelengths or wavelength ranges, is also disclosed.
    Type: Application
    Filed: January 10, 2005
    Publication date: July 14, 2005
    Inventors: Muthukumaran Packirisamy, Ashok Balakrishnan