Dual grating sensing system, dual grating sensor and detecting method thereof

A dual grating sensing system for detecting at least one property of an analyte, comprising:

• a substrate;
• a waveguide layer formed on the substrate, wherein the waveguide layer has a first double-sided grating structure and a second double-sided grating structure;
• an upper cover covered on the first double-sided grating structure and the second double-sided grating structure to form a channel between the waveguide layer and the upper cover, wherein the analyte flows in the channel;
• and
• a light source emitting a light, wherein the light couples into the waveguide layer via the first double-sided grating structure, and couples out of the waveguide layer via the second double-sided grating structure to detect the at least one property of the analyte,
• wherein the first and the second double-sided grating structures have a first sensitivity and a second sensitivity respectively, and a total sensitivity of the dual grating sensing system has an additive effect by the light passing through the first double-sided grating structure and the second double-sided grating structure.