Optical transmitter module

An optical transmitter module comprising:

• a light source for emitting a first light signal with a first wavelength, and a second light signal with a second wavelength;
• a first optical circulation unit comprising three optical couplers and three optical isolators, the optical couplers and the optical isolators alternately connected to one another to form a loop, the three optical couplers comprising a first optical coupler, a second optical coupler, and a third optical coupler, the first optical circulation unit comprising a first port at the first optical coupler, a second port at the second optical coupler, and a third port at the third optical coupler, the first port optically coupled to the light source;
• a first optical reflector optically coupled to the second port, the first optical reflector configured for reflecting the first light signal back to the second port to enter the first optical circulation unit, and allowing the second light signal to pass therethrough;
• and
• an output unit optically coupled to the third port to output the first light signal.