Fig. 11: All-optical implementation of the same linear intensity transformation at discrete wavelengths by a diffractive network under spatially incoherent illumination.

a The spatially incoherent diffractive network simultaneously performs the same intensity linear transformation A at N_w = 3 discrete wavelengths λ₁, λ₂, λ₃. b An arbitrarily chosen target permutation matrix A, together with the all-optical intensity linear transformations (\({\hat{{\boldsymbol{A}}}}_{\lambda }\)) performed by the trained spatially incoherent diffractive network (K = 5, N = 5 × 100² ≈ 2.035 × 2N_wN_iN_o) at the three designated wavelengths and the corresponding error matrices \({{\boldsymbol{\varepsilon }}}_{\lambda }=\left|{\boldsymbol{A}}-{\hat{{\boldsymbol{A}}}}_{\lambda }\right|\). Here |∙| denotes elementwise operation. c Average of the elements of the error matrix ε_λ, as a function of the spatially incoherent illumination wavelength λ