Absorption Efficiency of Traveling Wave Photodetectors in Superconducting Fiber Plasmon–Polariton Optical Waveguides

Abstract

By using an analytical model and a finite element method, we investigate a new, very sensitive, superconducting traveling wave photodetector made by an optical fiber, which includes a high index layer (LaAlO3) with small losses, a metallic (gold) layer, and two active superconducting layers (YBCO). While the fundamental guided degenerate mode HE11 is highly confined in the interior YBCO layer, the plasmon non-degenerate mode TM01 and plasmon degenerate mode HE12 are tightly confined in the exterior superconducting layer. In our structure of the fiber with five layers (without a buffer layer), the imaginary parts of the HE11, TM01, HE12 modes and the power absorption efficiency in superconducting layers are larger in comparison with that of a fundamental mode from a LaAlO3–YBCO–Au planar waveguide. The confinement regimes of the light and the power absorption efficiency in superconducting layers can be optimized by only acting on the fiber geometry.