Tamm-plasmon-polariton biosensor based on one-dimensional topological photonic crystal

Tamm-plasmon-polariton (TPP) has strong light absorption and polarization-independence, shows potential application in the optical biosensors. However, with the weak field confinement of the distributed Bragg reflector (DBR), the sensitivity enhancement of TPP biosensors require defect layers or nano-materials with strong light absorption. Herein, we propose a novel TPP biosensor by using one-dimensional topological photonic crystal (1D TPhC) as DBR, the working wavelength is 633 nm, where 1D TPhC is composed by two 1D photonic crystals (1D PhCs) with different topological invariants. The strong field confinement of 1D TPhC is employed to improve the light absorption of TPP, and enhance the susceptibility of the biosensor to the analyte. Since TPP is polarizationindependent, it has superior sensing performance in both transverse electric (TE) and transverse magnetic (TM) polarization modes. The sensitivity and Figure of Merit (FOM) are 2.6553 x 104 RIU-1 (1.3349 x 104 RIU-1) and 3.1238 x 107 RIU- 1deg- 1 (6.6745 x 108 RIU- 1deg- 1) for TM(TE)-polarization mode. The proposed TPP biosensor without defect layer, doesn't need consider the thickness and position of the sensing medium layer, shows high operational flexibility. Besides, with the protection of the topological edge state, this biosensor has high tolerance to the thickness deviations, which can reduce the requirements on fabrication. It is anticipated that the proposed TPP biosensor has excellent sensing performances, possesses great potentials in environmental monitoring, biological detection, etc.