A method for creating an optical binary digital transmit signal to be supplied to an optical transmission link including: operating an optical transmitter in such a state that mode hopping occurs between a predefined first and a predefined second optical mode of the optical transmitter if a binary digital modulation signal is supplied to the optical transmitter and creating a modulated optical output signal of the optical transmitter corresponding to the binary digital modulation signal supplied to the optical transmitter. The modulated optical output signal is optically filtered in such a way that at least a portion of the optical power spectrum of the modulated optical output signal caused by a selected one of the first and second optical modes is suppressed or at least substantially attenuated.