Optical delay element
First Claim
1. An optical delay element, comprising:
- a line defect optical waveguide formed in a photonic crystal structure, the photonic crystal structure including,a medium having a first refractive index, andan array of hole portions filled with material having a second refractive index less than the first refractive index, the array of hole portions being arranged in the medium so as to have a center to center pitch along a straight line between adjacent hole portions of a distance “
a,”
whereina width “
D”
of the line defect optical waveguide is greater than 0.7 times 30.5(“
a”
) and less than 0.9 times 30.5(“
a”
), wherein“
D”
=30.5(“
a”
) is the width of a common line defect optical waveguide formed from a single line defect photonic crystal, and whereina waveguide band of said line defect optical waveguide has a refractive index confinement mode and a photonic bandgap confinement mode, and the line defect optical waveguide guides light having a frequency higher than a frequency corresponding to the photonic bandgap confinement mode.
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Accused Products
Abstract
An optical delay element including a photonic crystal line defect optical waveguide is disclosed that has a large group refractive index and has small or nearly constant wavelength dispersion of the group refractive index in a wide wavelength region for practical use. The optical delay element includes a line defect optical waveguide formed in a photonic crystal structure, and the volume of the line defect optical waveguide is less than the volume of a single line defect optical waveguide. Thereby, the waveguide band of the line defect optical waveguide has two zero points in the third order dispersion curve of the line defect optical waveguide, and the sign of the third order dispersion curve is inverted near the zero points. Therefore, the waveguide band of the line defect optical waveguide is modified, and this enables expansion of the wavelength region having a large group refractive index, small wavelength dispersion of the group refractive index, and small wavelength dispersion of the speed of optical pulses.
12 Citations
19 Claims
-
1. An optical delay element, comprising:
-
a line defect optical waveguide formed in a photonic crystal structure, the photonic crystal structure including, a medium having a first refractive index, and an array of hole portions filled with material having a second refractive index less than the first refractive index, the array of hole portions being arranged in the medium so as to have a center to center pitch along a straight line between adjacent hole portions of a distance “
a,”
whereina width “
D”
of the line defect optical waveguide is greater than 0.7 times 30.5(“
a”
) and less than 0.9 times 30.5(“
a”
), wherein“
D”
=30.5(“
a”
) is the width of a common line defect optical waveguide formed from a single line defect photonic crystal, and whereina waveguide band of said line defect optical waveguide has a refractive index confinement mode and a photonic bandgap confinement mode, and the line defect optical waveguide guides light having a frequency higher than a frequency corresponding to the photonic bandgap confinement mode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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Specification