Surface plasmon resonance biosensor using coupled surface plasmons to decrease width of reflectivity dip

A surface plasmon resonance apparatus comprising:

• a prism;
• a first conducting layer contacting one face of the prism;
• a second conducting layer spaced apart from the first conducting layer to form a gap to receive a sample to be analyzed by the surface plasmon resonance apparatus;
• and
• a light source emitting an incident light beam having a wavelength λ0 entering the prism and incident on the face of the prism contacted by the first conducting layer at an adjustable incident angle α relative to a normal to the face of the prism contacted by the first conducting layer;
• wherein the gap has a thickness that enables generation of coupled surface plasmons when the incident angle α at which the incident light beam is incident on the face of the prism contacted by the first conducting layer is equal to a resonance angle determined by the wavelength λ0 of the incident light beam, an index of refraction of the first conducting layer and the second conducting layer, and an index of refraction of the sample.

A surface plasmon resonance apparatus comprising:

• a prism;
• a dielectric layer contacting one face of the prism;
• a conducting layer having a first surface contacting the dielectric layer and a second surface to contact a sample to be analyzed by the surface plasmon resonance apparatus;
• and
• a light source emitting an incident light beam having a wavelength λ0 entering the prism and incident on the face of the prism contacted by the dielectric layer at an adjustable incident angle α relative to a normal to the face of the prism contacted by the dielectric layer;
• wherein the conducting layer has a thickness that enables generation of slightly asymmetric coupled surface plasmons when the incident angle α at which the incident light beam is incident on the face of the prism contacted by the dielectric layer is equal to a resonance angle determined by the wavelength λ0 of the incident light beam, an index of refraction of the conducting layer, and an index of refraction of the sample.

A surface plasmon resonance apparatus comprising:

• a prism;
• a conducting layer contacting one face of the prism;
• a dielectric waveguide layer having a first surface contacting the conducting layer and a second surface to contact a sample to be analyzed by the surface plasmon resonance;
• and
• a light source emitting an incident light beam having a wavelength λ0 entering the prism and incident on the face of the prism contacted by the conducting layer at an adjustable incident angle α relative to a normal to the face of the prism contacted by the conducting layer;
• wherein the conducting layer has a thickness that enables generation of a coupled mode in which a single-interface surface plasmon propagating along an interface between the prism and the conducting layer is coupled with a waveguide mode propagating in the dielectric waveguide layer when the incident angle α at which the incident light beam is incident on the face of the prism contacted by the conducting layer is equal to a resonance angle determined by the wavelength λ0 of the incident light beam, an index of refraction of the conducting layer, and an index of refraction of the sample.