Sensing and Demodulation of Special Long-Period Fiber Gratings Induced by Scanning CO_𝟐 Laser Pulses

Figure 19

Schematic diagram of the CO₂ laser-grooved LPFG temperature sensor system based on the intensity modulation. 𝐶₁, 𝐶₂, 𝐶₃, and 𝐶₄ are 3 dB couplers [7].