It is disclosed an optical transmitter comprising a first mirror and a second mirror, an optical amplifier and an optical component comprising a first port, a second port and a third port. The optical component is configured so that a first and second diffraction orders of an optical signal at a given wavelength entering the optical component through the first port are focused at the second port and at the third port, respectively. The third port is optically connected to the second mirror. The first mirror and the second mirror delimit a cavity that comprises the optical component and the optical amplifier, the cavity being configured to emit a coherent optical radiation at the given wavelength through the second port.