An optical switching device for selectively routing spectral channels received by input ports to respective output ports selected based on a command, comprising: - input ports (A1, A2, A3) provided to receive multiplex input optical signals (WM1, WM2, WM3), respectively, each comprised of spectral channels carried by respective wavelengths, - output ports (Q1,... Qi,... Qa), - said switching device comprising: - a first stage comprising multiple wavelength selection modules (IWS1, IWS2, IWS3) whose inputs respectively constitute input ports (A1, A2, A3) of the switching device, each of said wavelength selection modules comprising an input and multiple outputs and being capable of carrying out a function of programmable demultiplexing of the spectral channels received at said input, selectively based on their respective wavelengths, to said outputs, so as to route to a chosen output of said module one or more channels selected based on a command signal (C11-C13) from among the spectral channels received at said input, - a second stage comprising at least one first wavelength selection module whose outputs respectively constitute output ports (Q1,... Qi,... Qa) of the switching device, said or each wavelength selection module comprising an input and multiple outputs and being able to carry out a function of programmable demultiplexing of the spectral channels received at said input, selectively based on their respective wavelengths, to said outputs, so as to route to a chosen output of said module one or more channels selected based on a command signal (C21-C26) from among the spectral channels received at said input, and - an intermediate stage coupling the input of said first wavelength selection module of the second stage both to a first output of a first wavelength selection module of the first stage and to a first output of a second wavelength selection module of the first stage. - input ports (A1, A2, A3) provided to receive multiplex input optical signals (WM1, WM2, WM3), respectively, each comprised of spectral channels carried by respective wavelengths, - output ports (Q1,... Qi,... Qa), - said switching device comprising: - a first stage comprising multiple wavelength selection modules (IWS1, IWS2, IWS3) whose inputs respectively constitute input ports (A1, A2, A3) of the switching device, each of said wavelength selection modules comprising an input and multiple outputs and being capable of carrying out a function of programmable demultiplexing of the spectral channels received at said input, selectively based on their respective wavelengths, to said outputs, so as to route to a chosen output of said module one or more channels selected based on a command signal (C11-C13) from among the spectral channels received at said input, - a second stage comprising at least one first wavelength selection module whose outputs respectively constitute output ports (Q1,... Qi,... Qa) of the switching device, said or each wavelength selection module comprising an input and multiple outputs and being able to carry out a function of programmable demultiplexing of the spectral channels received at said input, selectively based on their respective wavelengths, to said outputs, so as to route to a chosen output of said module one or more channels selected based on a command signal (C21-C26) from among the spectral channels received at said input, and - an intermediate stage coupling the input of said first wavelength selection module of the second stage both to a first output of a first wavelength selection module of the first stage and to a first output of a second wavelength selection module of the first stage.