Compact dual-mode waveguide crossing based on adjoint shape optimization

We design, fabricate, and characterize a compact dual-mode waveguide crossing on a silicon-on-insulator platform. The dual-mode waveguide crossing with high performance is designed by utilizing the adjoint shape optimization. This adjoint-method-based optimization algorithm is computationally efficient and yields the optimal solution in fewer iterations compared with other iterative schemes. Our proposed dual-mode waveguide crossing exhibits low insertion loss and low crosstalk. Experimental results show that the insertion losses at the wavelength of 1550 nm are 0.83 dB and 0.50 dB for TE0 and TE1 modes, respectively. The crosstalk is less than -20 dB for the two modes over a wavelength range of 80 nm. The footprint of the whole structure is only 5 x 5 mu m(2).

Automated summary

We have designed, fabricated, and characterized a compact dual-mode waveguide crossing on a silicon-on-insulator platform. The high-performance crossing structure is achieved through the use of adjoint shape optimization. Experimental results demonstrate low insertion loss and crosstalk, with insertion losses of 0.83 dB and 0.50 dB for TE0 and TE1 modes at 1550 nm wavelength, respectively, and crosstalk less than -20 dB for the two modes over a wavelength range of 80 nm. The total footprint of the structure is only 5 x 5 μm².