Photonic Emulator for Inverse Design

Inverse design has become a powerful tool widely used in the design of high-performance integrated photonic devices. However, current inverse design methods rely heavily on computationally intensive electromagnetic simulation or timeconsuming model training. Here, we proposed an efficient inverse design strategy, called a photonic emulator, that uses light propagation instead of electromagnetic simulation. We experimentally demonstrated the application of this photonic emulator for various typical single-and multiwavelength devices and functions, such as an optical multiple-input-multiple-output (MIMO) descrambler (at the modulation rate of 10 Gbit/s), matrix computation (percentage error < 2%), and a tunable wavelength selective switch (extinction ratio > 10 dB for three-wavelength routing). The photonic emulator enables high-precision reconfiguration of the design target on the basis of precise tuning of the effective refractive index near the pixels in the design area and fast feedback of the optical response in real time. Our work shows that the concept of propagation-as-computation can be used for inverse design to provide an efficient method for designing reconfigurable integrated photonic devices.