A data center, wherein the data center comprises a wavelength source, a first optical component, a first communications device, and a second communications device, the first optical component comprises a first port, a second port, and a third port, the first communications device comprises at least one of a server and a switch, and the second communications device comprises at least one of a server and a switch; wherein the wavelength source is configured to generate an N-wavelength laser beam, wherein N is an integer greater than or equal to 1; the first port of the first optical component is configured to receive an M-wavelength laser beam from the wavelength source, wherein M is an integer greater than or equal to 1 and less than or equal to N; the second port of the first optical component is configured to send the M-wavelength laser beam to the first communications device using a single optical cable, wherein the M-wavelength laser beam comprises at least a first-wavelength laser beam; the second port of the first optical component is further configured to receive a modulated first optical signal from the first communications device, wherein the modulated first optical signal is a modulated optical signal obtained after the first communications device modulates a service signal onto the first-wavelength laser beam; and the third port of the first optical component is configured to send the modulated first optical signal to the second communications device; wherein the first communications device comprises a first port, wherein the first port of the first communications device is configured to receive the M-wavelength laser beam from the first optical component using the single optical cable, and the first port of the first communications device is further configured to send the modulated first optical signal to the first optical component; wherein, the first communications device comprises a colorless optical sending module comprising a single modulator to modulate the service signal onto the first-wavelength laser beam in a wavelength insensitive manner. the wavelength source is configured to generate an N-wavelength laser beam, wherein N is an integer greater than or equal to 1; the first port of the first optical component is configured to receive an M-wavelength laser beam from the wavelength source, wherein M is an integer greater than or equal to 1 and less than or equal to N; the second port of the first optical component is configured to send the M-wavelength laser beam to the first communications device using a single optical cable, wherein the M-wavelength laser beam comprises at least a first-wavelength laser beam; the second port of the first optical component is further configured to receive a modulated first optical signal from the first communications device, wherein the modulated first optical signal is a modulated optical signal obtained after the first communications device modulates a service signal onto the first-wavelength laser beam; and the third port of the first optical component is configured to send the modulated first optical signal to the second communications device; wherein the first communications device comprises a first port, wherein the first port of the first communications device is configured to receive the M-wavelength laser beam from the first optical component using the single optical cable, and the first port of the first communications device is further configured to send the modulated first optical signal to the first optical component; wherein, the first communications device comprises a colorless optical sending module comprising a single modulator to modulate the service signal onto the first-wavelength laser beam in a wavelength insensitive manner.