Signal generating circuit, optical signal transmitting apparatus, signal receiving circuit, method for establishing optical signal synchronization, and optical signal synchronization system

A signal generating circuit in optical communication, the signal generating circuit comprising:

• a specific frequency band signal generating circuit that generates a specific frequency band signal having power concentrated on two or more specific frequencies;
• and
• at least one signal synthesizing circuit that receives an input of the specific frequency band signal generated by the specific frequency band signal generating circuit, and inserts the specific frequency band signal into a signal sequence to be transmitted, to generate a transmission signal sequence,
• wherein the specific frequency band signal generating circuit matches a position of at least one frequency component included in both adjacent frequency channels in a frequency region in which the adjacent frequency channels overlap, and controls an amplitude and a phase of the at least one frequency component so as to cancel each other, to generate the specific frequency band signal.

A signal generating circuit in optical communication, the signal generating circuit comprising:

• a specific frequency band signal generating circuit that generates a specific frequency band signal having power concentrated on two or more specific frequencies;
• and
• at least one signal synthesizing circuit that receives an input of the specific frequency band signal generated by the specific frequency band signal generating circuit, and inserts the specific frequency band signal into a signal sequence to be transmitted, to generate a transmission signal sequence,
• wherein the specific frequency band signal generating circuit generates specific frequency band signals having a plurality of periods and specific frequency band signals obtained by rotating phases of the specific frequency band signals having the plurality of periods, and synthesizes or multiplies the specific frequency band signals having the plurality of periods by the specific frequency band signals having the rotated phases to generate a signal obtained by synthesis or multiplication as the specific frequency band signal.

An optical signal transmitting apparatus comprising:

• a signal generating circuit in optical communication;
• and
• an electro-optical conversion/frequency-division multiplexing circuit,
• wherein the signal generating circuit comprises:
• a specific frequency band signal generating circuit that generates a specific frequency band signal having power concentrated on two or more specific frequencies;
• and
• at least one signal synthesizing circuit that receives an input of the specific frequency band signal generated by the specific frequency band signal generating circuit, and inserts the specific frequency band signal into a signal sequence to be transmitted, to generate a transmission signal sequence,
• the specific frequency band signal is a binary phase shift keying (BPSK) signal sequence known between an optical signal transmitting apparatus and an optical signal receiving apparatus that perform the optical communication and configured by an alternating signal,
• the at least one signal synthesizing circuit inserts at least one BPSK signal sequence into a front portion or an end portion of the signal sequence to be transmitted, to generate the transmission signal sequence, and
• the electro-optical conversion/frequency-division multiplexing circuit converts a plurality of signal sequences respectively generated by a plurality of signal synthesizing circuits in the signal generating circuit into optical signals corresponding to different frequency bands, and matches at least one frequency component of the converted optical signals.