A multicarrier-based optical transmit subsystem, comprising: a comb-shaped light source apparatus, configured to generate and output polychromatic light; a microring group, comprising multiple microring modulators, wherein each of the multiple microring modulators comprises an input end and a download end, the input end of each of the multiple microring modulators is connected to the comb-shaped light source apparatus, and the multiple microring modulators each are configured to filter and modulate the polychromatic light, each microring modulator responds to one beam of monochromatic light or light with one frequency, and output the optical signals by using respective download ends of the multiple microring modulators; and a plurality of public waveguides, connected to the download ends of the multiple microring modulators, and configured to multiplex the optical signals with different frequencies, the plurality of microring modulators are grouped into multiple microring subgroups whose quantity is the same as that of the public waveguides, and the microring subgroups are connected to the public waveguides in a one-to-one correspondence manner, wherein the comb-shaped light source apparatus comprises: one monochromatic light source; and multiple frequency shifting apparatuses, connected to the light source, and configured to perform frequency shifting on light emitted by the light source, to obtain polychromatic light; wherein the quantity of the microring modulators in the microring group is equal to or greater than a quantity of the frequency shifting apparatuses, the frequency shifting apparatuses are connected in series by using a waveguide, and the output of each one of the frequency shifting apparatuses is connected to at least one microring modulator in the microring group. a comb-shaped light source apparatus, configured to generate and output polychromatic light; a microring group, comprising multiple microring modulators, wherein each of the multiple microring modulators comprises an input end and a download end, the input end of each of the multiple microring modulators is connected to the comb-shaped light source apparatus, and the multiple microring modulators each are configured to filter and modulate the polychromatic light, each microring modulator responds to one beam of monochromatic light or light with one frequency, and output the optical signals by using respective download ends of the multiple microring modulators; and a plurality of public waveguides, connected to the download ends of the multiple microring modulators, and configured to multiplex the optical signals with different frequencies, the plurality of microring modulators are grouped into multiple microring subgroups whose quantity is the same as that of the public waveguides, and the microring subgroups are connected to the public waveguides in a one-to-one correspondence manner, wherein the comb-shaped light source apparatus comprises: one monochromatic light source; and multiple frequency shifting apparatuses, connected to the light source, and configured to perform frequency shifting on light emitted by the light source, to obtain polychromatic light; one monochromatic light source; and multiple frequency shifting apparatuses, connected to the light source, and configured to perform frequency shifting on light emitted by the light source, to obtain polychromatic light; wherein the quantity of the microring modulators in the microring group is equal to or greater than a quantity of the frequency shifting apparatuses, the frequency shifting apparatuses are connected in series by using a waveguide, and the output of each one of the frequency shifting apparatuses is connected to at least one microring modulator in the microring group.