Laser diodes include SH, double heterojunction (DH) and quantum well (QW) laser diodes. Quantum well laser diode has the advantages of low threshold current and high output power, so it becomes the mainstream product in the market. Compared with lasers, laser diodes have the advantages of high efficiency, small size and long lifespan. In the backtransmission module of bidirectional optical receiver, the quantum well laser diode is generally used as the light source for uplink transmission.
