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Optical filter and method of making the same

  • US 6,337,937 B1
  • Filed: 05/17/1999
  • Issued: 01/08/2002
  • Est. Priority Date: 05/18/1998
  • Status: Expired due to Fees
First Claim
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1. An optical filter comprising:

  • an optical waveguide having a core region which has a predetermined refractive index, and a cladding region which is provided on an outer periphery of said core region and has a lower refractive index than said core region;

    a first filter region arranged at a predetermined position at least in said core region, and provided with a first long-period grating attaining an attenuation peak at a first wavelength by mode coupling, a refractive index of said first filter region varying with a first period; and

    a second filter region arranged at a predetermined position at least in said core region, and provided with a second long-period grating attaining an attenuation peak at a second wavelength different from said first wavelength by mode coupling, a refractive index of said second long-period grating varying with a second period;

    wherein the order of cladding mode in light attenuated by said first long-period grating to couple with a core mode thereof differs from the order of cladding mode in light attenuated by said second long-period grating to couple with a core mode thereof.

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