An optical dual-comb source apparatus comprising: a continuous wave laser light source having a multimode in which at least two transverse modes or at least two longitudinal modes of light are simultaneously emitted and configured to output laser light ; a first optical microresonator comprising a first nonlinear material with a refractive index which is variable based on a light intensity, wherein the first optical microresonator has a plurality of different resonance modes; and a second optical microresonator comprising a second nonlinear material with a refractive index which is variable based on a light intensity, wherein the second optical microresonator has a plurality of different resonance modes, wherein the first optical microresonator and the second optical microresonator are each configured to interact with the laser light and thereby generate a first optical frequency comb (C1) and a second optical frequency comb (C2), the second optical frequency comb having a mode interval different from a mode interval of the first optical frequency comb, and an input coupler configured to input the laser light emitted by the continuous wave laser into each of the first optical microresonator and the second optical microresonator , and a first output coupler to output the first optical frequency comb (C1) generated by the first optical microresonator , and a second output coupler to output the second optical frequency comb (C2) generated by the second optical microresonator , wherein the first optical microresonator and the second optical microresonator are configured to share the input coupler , wherein the first optical microresonator and the second optical microresonator are respectively arranged adjacent to both sides of the input coupler , the first output coupler is arranged at an outer periphery of the first optical microresonator , and the second output coupler is arranged at an outer periphery of the second optical microresonator . a continuous wave laser light source having a multimode in which at least two transverse modes or at least two longitudinal modes of light are simultaneously emitted and configured to output laser light ; a first optical microresonator comprising a first nonlinear material with a refractive index which is variable based on a light intensity, wherein the first optical microresonator has a plurality of different resonance modes; and a second optical microresonator comprising a second nonlinear material with a refractive index which is variable based on a light intensity, wherein the second optical microresonator has a plurality of different resonance modes, wherein the first optical microresonator and the second optical microresonator are each configured to interact with the laser light and thereby generate a first optical frequency comb (C1) and a second optical frequency comb (C2), the second optical frequency comb having a mode interval different from a mode interval of the first optical frequency comb, and an input coupler configured to input the laser light emitted by the continuous wave laser into each of the first optical microresonator and the second optical microresonator , and a first output coupler to output the first optical frequency comb (C1) generated by the first optical microresonator , and a second output coupler to output the second optical frequency comb (C2) generated by the second optical microresonator , wherein the first optical microresonator and the second optical microresonator are configured to share the input coupler , wherein the first optical microresonator and the second optical microresonator are respectively arranged adjacent to both sides of the input coupler , the first output coupler is arranged at an outer periphery of the first optical microresonator , and the second output coupler is arranged at an outer periphery of the second optical microresonator . <EOS>