Wide shoulder, high order mode filter for thick-silicon waveguides
First Claim
1. An optical filter for attenuating higher-order transverse modes, the optical filter comprising:
- a shoulder slab, wherein;
the shoulder slab is formed of a first material having a first index of refraction and is disposed atop a second material having a second index of refraction, the first index of refraction being higher than the second index of refraction; and
a waveguide ridge disposed atop the shoulder slab, wherein;
the waveguide ridge is formed of the first material;
the waveguide ridge forms an input width in a first waveguide section along a direction of beam propagation, wherein;
a first filter section, formed by the shoulder slab and the waveguide ridge in the first waveguide section, is capable of guiding light of a fundamental mode and the higher-order transverse modes along the direction of beam propagation; and
the waveguide ridge tapers adiabatically inward from the input width to a reduced width, in a second waveguide section that adjoins the first waveguide section along the direction of beam propagation, wherein;
a second filter section, formed by the shoulder slab and the tapering waveguide ridge in the second waveguide section, is capable of guiding the fundamental mode, wherein the higher-order transverse modes are pushed into the shoulder slab where they are less strongly guided than the fundamental mode,such that a proportion of energy guided in the fundamental mode, to energy guided in the higher-order transverse modes, increases along the direction of beam propagation in the second filter section.
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Accused Products
Abstract
An optical filter for attenuating higher-order modes in an optical waveguide includes a shoulder slab formed of a first material having a first index of refraction and disposed on a second material having a second index of refraction, the first index of refraction being higher than the second index of refraction. The shoulder slab defines a near end having a first width, an intermediate section, adjacent to the first end section, and a far end section, adjacent to the intermediate section and opposite the first end section along a direction of beam propagation. The optical filter also includes a waveguide ridge, formed of the first material and disposed atop the shoulder slab, that traverses the shoulder slab, and is configured to guide light of a fundamental mode along the direction of beam propagation from the near end section to the far end section.
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Citations
19 Claims
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1. An optical filter for attenuating higher-order transverse modes, the optical filter comprising:
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a shoulder slab, wherein; the shoulder slab is formed of a first material having a first index of refraction and is disposed atop a second material having a second index of refraction, the first index of refraction being higher than the second index of refraction; and a waveguide ridge disposed atop the shoulder slab, wherein; the waveguide ridge is formed of the first material; the waveguide ridge forms an input width in a first waveguide section along a direction of beam propagation, wherein; a first filter section, formed by the shoulder slab and the waveguide ridge in the first waveguide section, is capable of guiding light of a fundamental mode and the higher-order transverse modes along the direction of beam propagation; and the waveguide ridge tapers adiabatically inward from the input width to a reduced width, in a second waveguide section that adjoins the first waveguide section along the direction of beam propagation, wherein; a second filter section, formed by the shoulder slab and the tapering waveguide ridge in the second waveguide section, is capable of guiding the fundamental mode, wherein the higher-order transverse modes are pushed into the shoulder slab where they are less strongly guided than the fundamental mode, such that a proportion of energy guided in the fundamental mode, to energy guided in the higher-order transverse modes, increases along the direction of beam propagation in the second filter section. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for filtering higher-order transverse modes in a ridge waveguide, the method comprising:
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transmitting a beam of light, comprising a fundamental mode and one or more higher-order transverse modes, along a direction of beam propagation in a first ridge waveguide, wherein the first ridge waveguide includes; a waveguide shoulder slab, formed of a first material disposed atop a substrate material, the first material having a higher index of refraction than the substrate material, and a waveguide ridge, formed of the first material, disposed atop the waveguide shoulder slab and having an input waveguide ridge width, wherein a combination of the waveguide ridge and the waveguide shoulder slab is capable of guiding the fundamental mode and the one or more higher-order transverse modes; coupling the beam of light along the direction of beam propagation into an optical filter, wherein the optical filter comprises; a filter shoulder slab, formed of the first material and disposed atop the substrate material, and a filter ridge, formed of the first material, disposed atop the filter shoulder slab and having a filter ridge width, wherein; the filter ridge width matches the input waveguide ridge width where the beam of light couples from the first ridge waveguide into the optical filter, and the filter ridge width decreases by adiabatically tapering along the direction of beam propagation such that the fundamental mode continues to be guided by the filter ridge, while at least a portion of the one or more higher-order transverse modes are pushed into the filter shoulder slab, attenuating the one or more higher-order transverse modes in the filter ridge; and coupling the fundamental mode into a second ridge waveguide, after the fundamental mode has passed through the optical filter and the one or more higher-order transverse modes are attenuated in the filter ridge. - View Dependent Claims (14, 15, 16, 17, 18)
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19. An optical filter for reducing higher-order transverse modes in an output of a semiconductor laser, the optical filter comprising:
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a shoulder slab, wherein; the shoulder slab is formed of a first material having a first index of refraction and is disposed atop a second material having a second index of refraction, the first index of refraction being higher than the second index of refraction; and a waveguide ridge disposed atop the shoulder slab, wherein; the waveguide ridge is formed of the first material; the waveguide ridge forms an input width in a first waveguide section along a direction of beam propagation, wherein; a first filter section, formed by the shoulder slab and the waveguide ridge in the first waveguide section, is capable of guiding light of a fundamental mode and the higher-order transverse modes along the direction of beam propagation; and the waveguide ridge tapers adiabatically inward from the input width to a reduced width, in a second waveguide section that adjoins the first waveguide section along the direction of beam propagation, wherein; a second filter section, formed by the shoulder slab and the tapering waveguide ridge in the second waveguide section, is capable of guiding the fundamental mode, wherein the higher-order transverse modes are pushed into the shoulder slab where they are less strongly guided than the fundamental mode, and wherein the optical filter is operably coupled within an optical cavity of the semiconductor laser, and increases a proportion of energy in the fundamental mode, to energy in the higher-order transverse modes, in the output of the laser.
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Specification