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US 7,397,987 B2Granted
Resonantly enhanced grating coupler
AssigneeCalifornia Institute of Technology
InventorsJeremy Witzens, Axel Scherer
Life of this patent
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Abstract
An apparatus and method for increasing efficiency of grating couplers are disclosed. The apparatus through the use of a defect or a reflective element allows coupling of light around a normal or nearly normal angle with a high efficiency. The method disclosed teaches how to increase the efficiency of a grating coupler through the use of a defect or a mirror. The apparatus and method can be of particular utility in the context of optical clocking implemented with a III-V chip flip-chip bonded on a CMOS chip.
Claims10
A grating coupler comprising:
- a first waveguide having an axis, wherein the first waveguide guides light in a direction parallel to the axis of the waveguide;
- and
- a first grating associated with the waveguide, the first grating comprising a first plurality of grates and a second plurality of grates separated by a first distance from the first plurality of grates, said first distance being controllable in accordance with a profile of light to be input into the waveguide or extracted from the waveguide,
- wherein the first plurality of grates, the second plurality of grates and the first distance are selected so that at least one between the first plurality of grates and the second plurality of grates acts both as a reflective element and a coupler,
- wherein the reflective element is such that light parallel to the axis of the waveguide is reflected in a direction parallel to the axis, and
- wherein the grates are curved grates.
3 more elements
A grating coupler comprising:
- a first waveguide having an axis, wherein the first waveguide guides light in a direction parallel to the axis of the waveguide;
- and
- a first grating associated with the waveguide, the first grating comprising a first plurality of grates and a second plurality of grates separated by a first distance from the first plurality of grates, said first distance being controllable in accordance with a profile of light to be input into the waveguide or extracted from the waveguide,
- wherein the first plurality of grates, the second plurality of grates and the first distance are selected so that at least one between the first plurality of grates and the second plurality of grates acts both as a reflective element and a coupler,
- wherein the reflective element is such that light parallel to the axis of the waveguide is reflected in a direction parallel to the axis,
- wherein grates of the first plurality of grates are equidistanced therebetween and grates of the second plurality of grates are equidistanced therebetween, and wherein a distance between grates of the first plurality of grates is different from a distance between grates of the second plurality of grates, and
- wherein the distance between grates of the first plurality of grates is half the distance between grates of the second plurality of grates.
4 more elements
An arrangement comprising:
- a waveguide having an axis, wherein the first waveguide guides light in a direction parallel to the axis of the waveguide;
- a first grating formed in the waveguide, the first grating having a first periodicity, the waveguide and the first grating forming a first reflective element;
- and
- a second grating formed in the waveguide, the second grating having a second periodicity, the waveguide and the second grating forming a second reflective element, the first reflective element and the second reflective element forming an optical resonator,
- wherein at least one between the first grating and second grating couples light to or from the waveguide in a direction not parallel to the axis of the waveguide,
- wherein at least one between the first reflective element and the second reflective element is a distributed Bragg reflector, and wherein the second periodicity is half the first periodicity.
3 more elements
A method to increase efficiency of a grating coupler comprising:
- providing a first grating coupler with a grating coupler periodicity;
- providing a resonant mechanism;
- and
- combining the first grating coupler with the resonant mechanism in a waveguide having an axis, wherein:
- the waveguide guides light in a direction parallel to the axis of the waveguide and the first grating coupler couples light to or from the waveguide in a direction not parallel to the axis of the waveguide,
- wherein the resonant mechanism is a defect inside the first grating coupler.
3 more elements
A method to increase efficiency of a grating coupler comprising:
- providing a first grating coupler with a grating coupler periodicity,
- providing a resonant mechanism;
- and
- combining the first grating coupler with the resonant mechanism in a waveguide having an axis, wherein:
- the waveguide guides light in a direction parallel to the axis of the waveguide and the first grating coupler couples light to or from the waveguide in a direction not parallel to the axis of the waveguide, and
- wherein the resonant mechanism is a distributed Bragg reflector having a reflector periodicity which is half the first grating coupler periodicity.
3 more elements
Dependencies are inferred from the claim text.