Broad band, low power electro-optic modulator apparatus and method with segmented electrodes

An electro-optic modulator, comprising:

• a substrate,
• an optical transmission network on said substrate,
• respective electrodes on said substrate for successive segments of said optical transmission network, and
• modulating signal transmission lines disposed lateral to said optical transmission network for transmitting modulating signals to respective ones of said electrodes to modulate an optical signal transmitted through said optical network, said modulating transmission lines having respective input ends and individual lengths that are selected so that modulating signals applied to the input ends of said modulating transmission lines with a predetermined phase relationship reach their respective electrodes in synchronism with the propagation of an optical signal through said optical transmission network,
• wherein said modulating transmission lines comprise electrical transmission lines that are substantially parallel, with the electrode ends of said transmission lines disposed along a line that is generally parallel to said optical transmission network, and the input ends of said transmission lines disposed along a line that is at a predetermined angle to said optical transmission network, said angle being selected to establish respective electrical transmission line lengths that produce electrical signal propagation delays corresponding to said synchronism between the application of electrical signals to said electrodes and the propagation of an optical signal through said optical transmission network, and said angle is defined by ##EQU4## where .phi. is the angle, c is the speed of light in a vacuum a is the speed of optical propagation through said optical network, and .epsilon. is the effective dielectric constant of said electrical transmission lines for said electrical modulating signals.

A Mach-Zehnder interferometric optical modulator, comprising:

• a pair of continuous elongate optical transmission lines organized into a plurality of successive segments,
• a plurality of mutually discrete segmented source electrodes disposed in cascade in the direction of optical transmission adjacent to said optical transmission lines, with one source electrode for each successive transmission line segment,
• respective segmented reference electrodes for each source electrode segment, and
• means for applying electrical modulating signals to said electrodes in synchronism with the transmission of optical signals through said optical transmission lines.

A method of modulating an optical signal, comprising:

• transmitting said optical signal through an optical transmission network that is disposed on a substrate,
• applying respective electrical modulating signals to successive segments of said optical transmission network in synchronism with the transmission of an optical signal through said network, and
• supplying said electrical modulating signals to said segments along a plane lateral to said optical transmission network,
• wherein said electrical modulating signals are transmitted along respective signal paths that are generally coplanar with said optical transmission network, the respective lengths of said paths being selected so that input modulating signals that have a predetermined phase relationship arrive at said optical transmission network in synchronism with the transmission of an optical signal through said network.