Figure 1.

Universal architecture scheme. The proposed architecture involving alternating layers of random unitary matrices F and diagonal phase shifts layers (PL) $\{{\varphi }_n^{(p)}\}$, with $p=1,\dots ,N+1$. The upper insets depict the modulus and argument of the potential candidates for the unitary matrix F, which have been selected as the DFT, DFrFT, and a random unitary matrix. The lower insets illustrate potential photonic implementations to perform the unitary matrix F.