Design of Strain-Sensing Devices in Microscale by Using Surface Plasmon Polaritons

We have presented a strain-sensing device in microscale by using surface plasmon polaritons and multimode interference effects. The device is numerically investigated by the finite-difference time-domain method. Optimum depths and length of the structure are designed for sensing a strain. The size of the designed structure is several micrometers and is about a thousandth compared with a fiber Bragg grating strain sensor. The sensitivity of the designed structure is 11.34 pm/μ𝜖 that is about ten times larger than that of a fiber Bragg grating strain sensor. The temperature sensitivity of the designed structure is 34.43 pm/ ∘C. This temperature sensitivity is three times larger than that of a fiber Bragg grating strain sensor. Therefore, temperature compensation techniques are needed for the structure. The presented structure has a simple design such as a plasmonic waveguide with a trench structure. The simple structural design device has a capability of being used in micro- and nano-electromechanical systems.