Patent ID: 6678428
Filing Date: 2004-01-13
Classification: G02F

Abstract:
An optical modulator comprising:a substrate having a predetermined optical effect; an optical waveguide formed on said substrate, being branched into first and second waveguide arms at a first Y-branch waveguide and thereafter merged into one again at a second Y-branch waveguide; a first signal electrode formed on said substrate, for transmitting a first electric signal which interacts with a first light propagating through the first waveguide arm in a predetermined manner; a second signal electrode formed on said substrate, for transmitting a second electric signal which interacts with a second light propagating through the second waveguide arm in a predetermined manner; and an earthed electrode formed on said substrate, wherein, when time for the first electric signal to transmit from a first input end of said first signal electrode to a first interaction start point, is a first progression time, the first input end being where the first electric signal is supplied and the first interaction start point being where the first light and the first electric signal start the interaction, time for the first light to propagate from a branching point of the first Y-branch waveguide to the first interaction start point is a first propagation time, time for the second electric signal to transmit from a second input end of said second signal electrode to a second interaction start point, is a second progression time, the second input end being where the second electric signal is supplied and the second interaction start point being where the second light and the second electric signal start the interaction, and time for the second light to propagate from the branching point to the second interaction start point is a second propagation time, a difference between an absolute value of a difference between the first progression time and the first propagation time and an absolute value of a difference between the second progression time and the second propagation time is 0 or an integer multiple of one-fourth a period of the first and the second electric signals.