Wave guide sensor

A method comprising:

• determining, by simulation of a hybrid waveguide of a sensor comprising a dielectric optical waveguide lying on a dielectric support layer and being surrounded by a dielectric fluid, dimensions of a transverse section of a first dielectric optical waveguide, the simulation of the sensor being performed without accounting for any surface waveguide, the dimensions being determined such that, for an optical mode of a signal propagating in the first dielectric optical waveguide, an effective optical index of the optical mode is lower than an refractive index of the dielectric fluid;
• determining, by simulation of the sensor in which the transverse section of the first dielectric optical waveguide has the determined dimensions, a position of a first surface waveguide with respect to the first dielectric optical waveguide so that an effective optical index of the optical mode in the hybrid waveguide is greater than the refractive index of the dielectric fluid;
• and
• manufacturing the sensor with the determined dimensions and the determined position, wherein the sensor comprises a hybrid waveguide comprising:
• a first dielectric optical waveguide lying on and in contact with a dielectric support layer;
• a first surface waveguide optically coupled to the first dielectric optical waveguide, parallel to the first dielectric optical waveguide, and lying on the dielectric support layer, the first surface waveguide comprising a lateral surface configured to guide a surface mode, the first surface waveguide comprising a metal layer and a substrate layer made of a different material than the metal layer, the metal layer covering the substrate layer and comprising the lateral surface;
• and
• a cavity intended to be filled with a dielectric fluid, separating laterally the first dielectric optical waveguide from the lateral surface of the first surface waveguide.

A method of forming a sensor comprising a hybrid waveguide, the method comprising:

• forming an optical waveguide disposed over a dielectric support layer;
• forming a first plasmonic waveguide and a second plasmonic waveguide disposed over the dielectric support layer, the first plasmonic waveguide being oriented along a first lateral surface of the optical waveguide, the second plasmonic waveguide being oriented along a second lateral surface of the optical waveguide, the first plasmonic waveguide comprising a first material and a second material made of a different material than the first material, the first material covering a sidewall of the second material facing the optical waveguide, the first material forming a lateral surface of the first plasmonic waveguide;
• and
• forming a first cavity disposed between the first plasmonic waveguide and the optical waveguide and a second cavity disposed between the second plasmonic waveguide and the optical waveguide, the first cavity being configured to be filled with a dielectric fluid and the second cavity being configured to be filled with the dielectric fluid.

A method of forming a sensor comprising a hybrid waveguide, the method comprising:

• forming an optical waveguide disposed over a dielectric support layer;
• forming a first plasmonic waveguide and a second plasmonic waveguide disposed over the dielectric support layer, the first plasmonic waveguide being oriented along a first lateral surface of the optical waveguide, the second plasmonic waveguide being oriented along a second lateral surface of the optical waveguide;
• and
• forming a first cavity disposed between the first plasmonic waveguide and the optical waveguide and a second cavity disposed between the second plasmonic waveguide and the optical waveguide, the first cavity being configured to be filled with a dielectric fluid and the second cavity being configured to be filled with the dielectric fluid, wherein forming the optical waveguide, forming the first plasmonic waveguide and forming the first cavity comprises:
• forming a first feature corresponding to the optical waveguide over the dielectric support layer;
• forming a pattern comprising a first material selectively etchable with respect to the first feature, the first material covering sidewalls and top surface of the first feature;
• forming a conformal liner over the pattern and exposed surfaces of the dielectric support layer;
• forming a second material over the conformal liner;
• using a planarizing process, opening a top surface of the first feature and forming a second feature comprising a portion of the second material and the conformal liner;
• forming an etch mask over the second feature;
• performing an etching process to remove the pattern exposed after forming the etch mask;
• and
• removing remaining etch mask to form the first cavity and the first plasmonic waveguide from the second feature.