Multi-wavelength laser

A frequency control method for a multi-wavelength laser, wherein the multi-wavelength laser comprises N wavelength-tunable lasers, N beam splitters, a phase modulator, and N−1 frequency difference detection apparatuses, and the N wavelength-tunable lasers comprise a reference wavelength-tunable laser and N−1 secondary wavelength-tunable lasers;

• the reference wavelength-tunable laser is connected to one beam splitter, the beam splitter comprises a first output port and a second output port, the first output port is used as an output port of the multi-wavelength laser, and the second output port is connected to the phase modulator;
• the phase modulator is separately connected to the N−1 frequency difference detection apparatuses;
• the N−1 secondary wavelength-tunable lasers one-to-one correspond to remaining N−1 beam splitters and the N−1 frequency difference detection apparatuses;
• the secondary wavelength-tunable laser is connected to a corresponding beam splitter, and the corresponding beam splitter comprises a third output port and a fourth output port;
• the third output port is used as an output port of the multi-wavelength laser, and the fourth output port is connected to a corresponding frequency difference detection apparatus;
• N is a positive integer not less than 2;
• and the frequency control method comprises:
• sending a part of a first laser signal output by a first wavelength-tunable laser to the phase modulator to generate a multi-wavelength optical signal, wherein a center frequency of the multi-wavelength optical signal is an output frequency of the first wavelength-tunable laser, and a frequency spacing of the multi-wavelength optical signal is a frequency of a drive signal of the phase modulator;
• sending a beam part of a laser signal output by the secondary wavelength-tunable laser and the multi-wavelength optical signal to the frequency difference detection apparatus to generate a control signal, wherein the control signal is based on the multi-wavelength optical signal and the beam part of the laser signal output by the secondary wavelength-tunable laser, and
• tuning an output frequency of the wavelength-tunable laser by using the control signal.