Interface device for performing mode transformation in optical waveguides
AssigneeNational Research Council of Canada
InventorsPavel Cheben, Siegfried Janz, Dan-Xia Xu, Jens Schmid, Adam Densmore, Jean Lapointe
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Abstract
An interface device for performing mode transformation in optical waveguides includes an optical waveguide core for propagating light of a particular wavelength or a plurality of wavelengths. The optical waveguide core terminates in a subwavelength grating configured to change the propagation mode of the light. The subwavelength grating has a pitch sufficiently less than the wavelength of the light to frustrate diffraction. The device can thus serve as an optical coupler between different propagating media, or as an anti-reflective or high reflectivity device.
Claims15
An interface device for performing mode transformation in optical waveguides, comprising:
- a first optical waveguide core for propagating light of a particular wavelength or a plurality of wavelengths in a longitudinal direction through said first optical waveguide core between an input face and an output face;
- a subwavelength grating embedded in said first optical waveguide core;
- said subwavelength grating having a series of transverse grating elements arrayed in said longitudinal direction between said input face and said output face such that light propagating in said first waveguide core between said input face and said output face successively passes said transverse grating elements;
- said grating elements having a pitch sufficiently less than the wavelength of the light to frustrate diffraction;
- and
- wherein a property of said subwavelength grating varies to effect a gradual change in effective mode index of said first optical waveguide core in the longitudinal direction, said property being selected from the group consisting of:
- duly ratio, width, pitch, modulation depth, material composition, and any combination thereof;
- and
- whereby the propagation mode of the light is modified during passage through said first waveguide core between said input face and said output face as said light passes said grating elements.
An optical waveguide device effecting mode transformation comprising:
- at least one cladding layer;
- a first waveguide core extending in a longitudinal direction for propagating a light beam of a particular wavelength or plurality of wavelengths between an input face and an output face, said light beam being confined within said first waveguide core by said at least one cladding layer;
- a longitudinal subwavelength grating etched into said waveguide core, said subwavelength grating having a series of transverse grating elements formed from said core and arrayed in said longitudinal direction such that light propagating in said core successively passes said transverse grating elements,
- said transverse grating elements having a pitch sufficiently less than the wavelength of the light beam to frustrate diffraction;
- and
- said wherein a property of said subwavelength grating varies in the longitudinal direction to provide said first waveguide core with an effective mode index that varies toward said output face.
Dependencies are inferred from the claim text.