Fiber coils had been widely investigated as optical current sensors for a long time. In this thesis we have fabricated the LMA-10 PCF coils. By using the Sagnac fiber loop, we can obtain the transmission spectrum of the PCF coils. The measured birefringence of the SMF coil and the PCF coil are 1.49¡Ñ10^-5 at £f= 959.27 nm and 1.31¡Ñ10^-5 at £f = 1264.3 nm, respectively. The birefringence of the SMF coil agrees well with the theoretical result. The properties of PCF coils for variant fiber turns and cylinder sizes are discussed. As we increase the number of fiber turns, the fringe spacing becomes smaller due to the increasing phase difference. The birefringence of the PCF coil decreases with the increasing cylinder radius. Besides, we also measure the temperature sensitivities of the SMF coil and PCF coil to be 130 pm/oC and 64.55 pm/ oC, respectively. We have also demonstrated the sensing properties of the PCF coils. By introducing a displacement along the cylinder, the bending on the PCF coil can be induced. The measured bending sensitivity is -3.732 nm/m^-1. In addition, the water depth sensing properties are obtained by horizontally and vertically immersing the PCF coils into the water. As we put the PCF coil horizontally into the water, the shift of the measured spectra shows a exponential relation to the water depth. As for the vertically immersed PCF coil, the linear water depth sensitivity is -11.658 nm/cm. Finally, we propose the transverse displacement sensor based on the PCF coil. The measured sensitivity to transverse displacement can be as large as 903.9 nm/cm.