Optical sensing device with multiple field-enhanced nano-volumes

An optical sensing system comprising:

• an optical sensing device comprising:
• a substrate;
• a first dielectric layer extending on the substrate;
• a plurality of pairs of opposite antennas patterned on the first dielectric layer, wherein opposite antennas are, in each of the pairs, separated by a gap g, which, on average, is between 1 nm and 50 nm, as measured in a direction x parallel to a main plane of the substrate, and wherein the pairs of antennas have different geometries;
• and
• a second dielectric layer that covers all of the antennas, so as to define an electro-magnetic field enhancement volume between the opposite antennas of each of the pairs, thanks to the gap g in between, in which volume electro-magnetic radiation can be concentrated for optically sensing an analyte via opposite antennas of each of the pairs, in operation, and
• an electro-optical light source;
• and
• an electro-optical light detector,
• wherein
• said electro-optical light source and said electro-optical light detector are configured for optically exciting the pairs of antennas and optically detecting signals therefrom, in a transmission geometry or a reflection geometry.

A method for optically sensing an analyte, the method comprising:

• providing an optical sensing device comprising:
• a substrate;
• a first dielectric layer extending on the substrate;
• a plurality of pairs of opposite antennas patterned on the first dielectric layer, wherein opposite antennas are, in each of the pairs, separated by a gap g, which, on average, is between 1 nm and 50 nm, as measured in a direction x parallel to a main plane of the substrate, and wherein the pairs of antennas have different geometries;
• and a second dielectric layer that covers all of the antennas, such that a plurality of electro-magnetic field enhancement volumes are defined, each between the opposite antennas of each of the pairs, thanks to the gap g in between, in which volumes electro-magnetic radiation can be concentrated for optically sensing an analyte via opposite antennas of each of the pairs, in operation,
• letting an analyte reach said electro-magnetic field enhancement volumes, while optically exciting the pairs of antennas of this device, to concentrate electro-magnetic radiation in said volumes, and
• optically detecting, via the plurality of pairs of opposite antennas, optical signals as modulated and/or generated by the analyte in said volumes.