Abstract: A transmitter and a receiver for an optical telecommunication system of the WDM type are disclosed. In one aspect, the transmitter uses a chromato-temporal encoder which, with each block of symbols to be transmitted, associates a code matrix, where each element of the matrix corresponds to a wavelength and a use of the channel. The transmitter includes multiple modulators, where each modulator modulates a laser beam at a wavelength during a use of the channel by an element corresponding to the code matrix. The beams modulated in this manner are multiplexed in an optical fiber. Another embodiment using both a wavelength and a polarization encoding is also proposed.