Liquid-crystal based Fabry–Perot interferometer displacement sensor

A Fabry-Perot interferometer displacement sensor is proposed and demonstrated. This sensor is prepared by inserting two ceramic ferrules into a polydimethylsiloxane (PDMS) hose to generate a Fabry-Perot cavity. The cavity is filled with nematic liquid crystals (NLCs), which induce a Vernier effect due to the birefringence of NLCs. The flexible PDMS hose makes the cavity length adjustable. A displacement sensor with sensitivity of ∼2.97 nm/μm and a dynamic range of 0.9 mm at the center wavelength of 1550 nm is experimentally demonstrated.