Patent ID: 11934050
Assignee: SUMITOMO ELECTRIC INDUSTRIES, LTD.
Field: Telecommunications (Electrical engineering)
Classification: CPC G  H | IPC G  H

Claim 7:
8. An optical transmitter comprising:
an optical modulator, in which a first child modulator and a second child modulator are connected in parallel to form a parent modulator; and
a bias controller that controls a first bias signal applied to the first child modulator and a second bias signal applied to the second child modulator,
wherein the bias controller includes
a waveform generating circuit configured to generate a first dither signal having a first frequency that is superimposed on the first bias signal, a second dither signal having a second frequency different from the first frequency that is superimposed on the second bias signal, and a third dither signal having a third frequency different from both the first frequency or the second frequency that is superimposed on the third bias signal applied to the parent modulator, and
a bias control circuit that includes a first circuit configured to detect a first error component of monitored optical power of an output light from the optical modulator having the first frequency, a second circuit configured to detect a second error component of monitored optical power of the output light having a beat frequency of the second frequency and the third frequency, and an adder configured to generate a first error signal for controlling the first bias signal based on the first error component and the second error component.