Shallow etched chirped silicon subwavelength grating coupler designed by weak form

Abstract

In this paper, the complex energy band of photonic crystals is calculated in weak form, and the diffraction coefficient 𝑛௜ of the subwavelength grating is obtained, and the chirped subwavelength grating is deterministically designed. For the two polarization states of TE and TM, different subwavelength grating structures are designed, and for the two polarization states, the results of simulation show that the device efficiency reaches 70%(-1.44dB) and 54%(-2.61dB), respectively, and the 3dB bandwidth is greater than 50nm.