Kretschmann‐ and Otto‐type surface plasmon resonance waveguide sensors in the terahertz regime
Jun Shibayama, Mitsutake Kota, Junji Yamauchi, Hisamatsu Nakano
Abstract
Abstract Kretschmann‐ and Otto‐type surface plasmon resonance (SPR) waveguide sensors are numerically investigated at terahertz frequencies. The reflectance of a three‐layer model for the Kretschmann‐type sensor is examined with the Fresnel equation, in order to determine the angle of incidence of the waveguide. Using the frequency‐dependent finite‐difference time‐domain method, the SPR response of the waveguide sensor is investigated for temperature variations. It is found that a high sensitivity of 2.63 × 10 −2 THz/K more than three times as large as that of the conventional SPR waveguide sensor is successfully achieved with a sensing length of about half that of the conventional one. The Otto‐type waveguide sensor is also examined and discussed. It is revealed that the sensor provides steep and stable SPR responses, maintaining the sensitivity of the Kretschmann‐type one.