Abstract: The interaction between the fundamental mode Gaussian optical field (HG00) and the high-order Hermite Gaussian optical field (HG10) and the subwavelength single-metal slits was studied by numerical simulation. It is found that under the same misalignment coupling, the HG10 light field can induce obvious unidirectional excitation of SPP. On this basis, a subwavelength metal slit pair structure is proposed. Numerical simulations show that under appropriate misalignment coupling, the HG10 mode field and the subwavelength metal slit pair can induce more remarkable unidirectional excitation of SPP. By optimizing the slit pitch and the incident light wavelength, the maximum split ratio reaches 2.6. The finite-difference time-domain method was used for numerical simulation in design optimization. The metal slit structure we designed is simple and easy to prepare, and the asymmetrical excitation of SPP has the characteristics of dynamic adjustment, which has potential application value in micronanophotonic integration and nanometer measurement.

Key words: micro-nano optics, surface plasmon polariton, unidirectional excitation, dynamic regulation, finite-difference time domain