Filter-free wavelength converters for separating and rejecting an optical input signal. A first input port couples a continuous wave (CW) light. A second input port couples an optical input signal. A multimode interference semiconductor optical amplifier (MMI-SOA) determines the output port with the input port and intensity-modulation of the CW light with the optical input signal. A first output port guides the converted signal, and a second output port guides the optical input signal.