Improving the Sensitivity of Grating Strain Sensor by Electromagnetically Induced Transparency

A Mach-Zehnder interferometer demodulation scheme based on slow light in electromagnetically induced transparency medium is proposed and applied to improve the sensing sensitivity of fiber Bragg grating strain sensors. Theoretical studies have found that higher group refractive index can be obtained under suitable control field conditions by the common Λ-type three-level atomic system, and the sensing sensitivity of fiber Bragg grating strain sensors is improved. Influences of the control field on the sensing range and sensing sensitivity are further analyzed. According to the theoretical calculation, when the control field G=60 MHz, the sensitivity of fiber Bragg grating strain sensor based on Mach-Zehnder interference demodulation can be increased by about 3 000 times. The proposed strain sensor demonstrates a high sensitivity of −40 Rad/με and strain measurement range of −50~50 nε.