High quality factor photonic crystal nanobeam cavity and method of designing and making same
AssigneePresident and Fellows of Harvard College
InventorsQimin Quan, Marko Loncar
Life of this patent
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Abstract
A deterministic design and manufacturing of an ultrahigh Q-factor, wavelength-scale optical cavity is invented and experimentally demonstrated. The design can be implemented on photonic crystal nanobeam cavities, which are based on 1D optical waveguides. The waveguide has dielectric index alternations that provide constructive interference and produces optical resonance.
Claims20
A method for deterministically making a nanobeam cavity without fine tuning, resizing and rescaling of the structure of the nanobeam cavity, wherein said nanobeam cavity is based on optical strip waveguides along which dielectric index alternations provide constructive interference and produce optical resonance and wherein said nanobeam cavity has a plurality of grating sections, comprising the steps of:
- selecting a period for said nanobeam cavity, wherein said period is fixed throughout the beam and said selected period opens a band gap;
- forming said nanobeam cavity to have a width selected to push a fundamental mode of said nanobeam cavity away from a light line;
- etching a first hole in a first grating section of said nanobeam cavity using a first filling fraction;
- etching a second hole in a second grating section of said nanobeam cavity using a second filling fraction, said second filling fraction being different than said first filling fraction;
- and
- etching a third hole in a third grating section of said nanobeam cavity using a third filling fraction, said third filling fraction being different than said first and said second filling fractions;
- wherein differences in sizes of said first, second and third holes create linearly increasing mirror strengths for said first, second and third grating sections.
A method for deterministically making a nanobeam cavity without fine tuning, resizing and rescaling of the structure of the nanobeam cavity, wherein said nanobeam cavity is based on optical strip waveguides along which dielectric index alternations provide constructive interference and produce optical resonance and wherein said nanobeam cavity has a plurality of grating sections, comprising the step of:
- selecting a period for said nanobeam cavity, wherein said selected period opens a band gap;
- forming said nanobeam cavity to have a width selected to push a fundamental mode of said nanobeam cavity away from a light line;
- selecting a periodicity for said nanobeam cavity that will yield a dielectric band edge;
- etching a first hole in a first grating section of said nanobeam cavity using a first filling fraction;
- etching a second hole in a second grating section of said nanobeam cavity using a second filling fraction, said second filling fraction being different than said first filling fraction;
- etching a third hole in a third grating section of said nanobeam cavity using a third filling fraction, said third filling fraction being different than said first and said second filling fractions;
- and
- tapering a width of said nanobeam cavity to linearly increase mirror strengths of said first, second and third grating sections;
- wherein differences in sizes of said first, second and third holes create linearly increasing mirror strengths for said first, second and third grating sections.
An optical device comprising:
- a strip waveguide having a width selected to push a fundamental mode of said strip waveguide away from a light line, wherein said strip waveguide comprises:
- a central cavity of length L, wherein said length L is from zero to λ/n, where λ is the operating wavelength and n is the refractive index of the material;
- and
- a plurality of gratings, wherein a distance between each grating is constant, said distance being selected to open a band gap;
- wherein each grating section has a filling fraction and on one side of said central cavity at least two grating sections have different selected filling fractions;
- and
- wherein a filling fraction of a hole adjacent said central cavity is selected to yield a dielectric band edge.
Dependencies are inferred from the claim text.