Data secrecy method for submarine cable system with failure and submarine cable system

A submarine cable system, comprising a first terminal station, a second terminal station, a trunk submarine cable connected between the first terminal station and the second terminal station, and at least one branching unit disposed on the trunk submarine cable, wherein each of the least one branching unit is connected to one branch, and each branch comprises a branch submarine cable connected to the branching unit and a branch station connected to the branch submarine cable;

• and the submarine cable system further comprises:
• a wavelength management device, disposed on an outgoing-light side of the first terminal station, wherein
• the wavelength management device is configured to:
• determine a first disaster tolerance set in response to that a failure occurs to a first branch, wherein the first branch is any branch in the submarine cable system, the first disaster tolerance set comprises at least one wavelength used for optical signals for transfer from the first terminal station to a first branch station, and the first branch station is a branch station on the first branch;
• and
• replace a target optical signal in a first optical signal with a virtual optical signal, wherein the first optical signal is an optical signal output from the first terminal station, the target optical signal comprises optical signals corresponding to the respective wavelengths in the first disaster tolerance set, the virtual optical signal is an optical signal that does not carry data content, and the virtual optical signal has a wavelength same as that of the target optical signal.