Programmable unitary photonic architecture based on random layers

This talk focuses on a universal unitary architecture based on layers of diagonal matrices and specific interlacing unitary matrices. Numerical evidence shows that such an interlacing matrix can have a random pattern as long as it fulfills the required density properties. In this regard, Haar-generated random matrices are suitable candidates that lead to suitable interlacing matrices. The efficacy of such random matrices is classified by a density criterion, which provides a priori conditions to ensure the validity of the interlacing matrix in question, reducing the computational workload due to heavy numerical optimization. This approach allows for more possibilities for further interlacing matrices beyond particular waveguide arrays. Also, the random nature of the interlacing matrix provides resilience due to manufacturing defects. These results are illustrated through some full-wave simulations.