Sensitivity-Enhanced Pressure Sensor With Hollow-Core Photonic Crystal Fiber

We experimentally demonstrate a sensitivity-enhanced fiber-optic pressure sensor using a simplified hollow-core photonic crystal fiber (SHC-PCF). The sensing head is fabricated by splicing a single mode fiber to a section of SHC-PCF, while the air claddings at the end of the PCF are selectively blocked by glue sealing and femtosecond laser machining. By immersing the end into water, a compressible Fabry-Pérot cavity can be formed in the fiber core of the PCF. Since the air core is opened up to the air claddings at the splicing joint, changing of environmental pressure will cost a large change of the cavity length to balance the pressure, which greatly enhances the pressure sensitivity of the sensor. A pressure sensitivity of 18.15 μm/kPa is experimentally demonstrated in the pressure range from 110 to 130 kPa. This sensor has potential applications in the area of highly sensitive pressure measurement.