US 6,983,085 B2
Optical transmission circuit
Tomoyoshi Kataoka, Yokohama (Japan); Akira Hirano, Yokohama (Japan); and Akihiko Matsuura, Yokosuka (Japan)
Assigned to Nippon Telegraph and Telephone Corporation, Tokyo (Japan)
Filed on Feb. 05, 2003, as Appl. No. 10/358,737.
Claims priority of application No. 2002-030406 (JP), filed on Feb. 07, 2002.
Prior Publication US 2003/0147577 A1, Aug. 07, 2003
Int. Cl. G02F 1/035 (2006.01)
U.S. Cl. 385—3 21 Claims
OG exemplary drawing
 
1. An optical transmission circuit comprising:
an optical modulator which modulates continuous light at wavelength λo as a carrier wavelength with a signal as a modulating signal at repetition frequency of fo Hz, and outputs alternating phase-inverted pulse light having power spectrum components of both side bands which have deviated by fo Hz to longer wavelength or shorter wavelength by fo Hz;
a bias voltage applying unit which applies a bias voltage to the optical modulator;
an optical power spectrum measuring unit having frequency resolution of less than fo Hz which measures the optical power spectrum of light output from the optical modulator; and
a control circuit which controls the bias voltage via the bias voltage applying unit based on measurements of the power spectrum of the output light of the optical modulator, so as to remove the carrier spectrum component of the carrier wavelength for maximizing the intensity of the power spectrums of both side bands.