Hyperelastic Polymer Fiber Fabry–Pérot Interferometer for Nanoforce Measurement

Herein we propose and experimentally demonstrate a hyperelastic polymer (polydimethylsiloxane, PDMS) fiber Fabry-Perot interferometer (FPI) for nanoforce measurement. The femtosecond laser pulse illumination and slit beam shaping are utilized to form refractive index modulation as the reflection mirrors of the FPI in the fiber. The PDMS fiber FPI, which exhibits an ultra-low Young's modulus, can be stretched by applied microforce and further result in the spectral variation of the FPI. In the measurement, another matching FPI is employed to introduce the optical Vernier effect. Due to the hyperelastic performance of the PDMS fiber and the magnification of the Vernier effect, the proposed sensor has force sensitivity as high as 45.721 nm μN ⁻¹ within linearly elastic range from 0 to 1400 μN. The proposed sensor is easily fabricated, assembled, and very stable, and it has therefore the potential to be a beneficial sensing technique for biochemical analysis and materials science.