Simulation of a SiN 2 × 2 adiabatic 3-dB coupler for 800-nm to 1000-nm wavelength range

We conducted numerical simulations on a 2×2 adiabatic 3-dB coupler tailored for the 800-nm to 1000-nm range, operating on a silicon-nitride (SiN) platform. Through the finite difference time domain method, we achieved a power splitting ratio close to 3 dB with a tight tolerance of ±0.27dB and an insertion loss below 0.19 dB across the wavelength range of 800 nm to 1000 nm. Additionally, we simulated a 2×2 switch utilizing two 2×2 adiabatic 3-dB couplers, revealing a theoretical extinction loss of approximately −14dB, particularly prominent around 900 nm.