An optical modulator element includes first and second optical modulators, an optical input terminal, and a branch coupler. Each of the first and second optical modulators includes a pair of Mach-Zehnder waveguides, a first optical coupler to split rays from the branch coupler into the pair of Mach-Zehnder waveguides, and a second optical coupler to combine rays transmitted through the pair of Mach-Zehnder waveguides. The first and second optical modulators are disposed in such a manner that a traveling direction of rays propagating through the pair of Mach-Zehnder waveguides of the first optical modulator and a traveling direction of rays propagating through the pair of Mach-Zehnder waveguides of the second optical modulator are angled toward each other.

An optical device is described. This optical device includes an electro-optical material having an X-cut, Y-propagate orientation. In particular, a Y crystallographic direction of the electro-optical material is parallel to an optical waveguide defined in the electro-optic material and an X crystallographic direction of the electro-optical material is parallel to a vertical direction of the optical device. By applying drive signals having an angular frequency to the electo-optic material, the optical device may perform modulation, corresponding to a traveling-wave configuration, of an optical signal based at least in part on the drive signals. where the modulation involves a polarization conversion and a frequency shift. The angular frequency of the drive signals may be selected to approximately cancel electro-optic cross terms in X-Z plane of the electro-optical material. Moreover, an amplitude of the drive signals may be selected so that the optical device emulates a half-wave-plate configuration.

An electro-optic modulator and an electro-optic device are provided. The electro-optic modulator includes: a first optical waveguide, a second optical waveguide, and a traveling wave electrode, where the traveling wave electrode includes a first grounding electrode, a first signal electrode, a second signal electrode, and a second grounding electrode that are spaced apart from each other; and the first optical waveguide and the second optical waveguide are both arranged between the first signal electrode and the second signal electrode. The electro-optic modulator has a plurality of extension sections along a extension direction thereof. The plurality of extension sections include a plurality of straight sections and at least one curved section. Each curved section is provided between two adjacent straight sections.

A distributed traveling-wave Mach-Zehnder modulator driver having a plurality of modulation stages that operate cooperatively (in-phase) to provide a signal suitable for use in a 100 Gb/s optical fiber transmitter at power levels that are compatible with conventional semiconductor devices and conventional semiconductor processing is described.

A segmented optical modulator includes two optical modulator segments located along a main face of a photonic chip, and two RF transmission lines connected to drive a corresponding one of the two optical modulator segments. A signal electrode of one of the transmission lines includes a segment that is vertically capacitively coupled to a plurality of spaced ground-connected metallic elements disposed in sequence along a length of the segment above or below thereof so as to be capacitively coupled thereto.

A segmented traveling wave Mach Zehnder optical modulator is described. The segmented traveling wave Mach Zehnder optical modulator may comprise two or more radio frequency (RF) segments, and each RF segment may be configured to support a modulating RF signal. The modulating RF signals may be configured to modulate an optical signal propagating along an optical path of the segmented traveling wave Mach Zehnder optical modulator. The RF modulating signal in the second RF segment may be generated by amplifying the modulating RF signal of the first RF segment, using an RF amplifier. The RF amplifier may be configured to amplify a band-pass spectral portion of the modulating RF signal.

Provided is a substrate-type optical waveguide, having a phase modulation function, (i) in which a reflection of a signal to be inputted via a coplanar line is restrained and (ii) which consumes less power. In a case where the substrate-type optical waveguide is partitioned into a plurality of sections by cross sections orthogonal to a direction in which light propagates through a core, a local capacitance in each of the plurality of sections gradually increases as a distance from an entrance end surface increases.

Aspects of the present disclosure are directed to a multi-section mismatched modulator. In one embodiment, a segmented bias electrode is provided along the length of the optical waveguide in the optical modulator. Each segmented bias electrode may have a pre-determined bias voltage that can reduce impedance mismatches along the length of the signal electrode to reduce echoes and ripples in the modulation signal. In an embodiment implemented as a P-I-N diode modulator, the bias electrode is used to apply a reverse bias transversely to the section of the diode modulator between the bias electrode and the signal electrode. According to an aspect, RF impedance along the length of the signal electrode can be tuned by adjusting the magnitude of the reverse-bias point at different segments of the bias electrode, and be matched to a desirable impedance value to reduce reflection and ripple effects.

A III-V/Si hybrid MOS optical modulator with a traveling-wave electrode for high-efficiency and high-bandwidth optical modulation is disclosed. The III-V/Si hybrid MOS optical modulator equipped with a traveling-wave electrode becomes a traveling-wave modulator. The traveling-wave modulator comprises a III-V compound semiconductor layer, a silicon layer and an oxide layer between the III-V compound semiconductor layer and the silicon layer. The traveling-wave modulator comprises of at least one first metallic layer, at least one second metallic layer and a semiconductor layer. The electrode trace width of each second metallic layer and the spacing between adjacent second metallic layers are adjusted to achieve the impedance and velocity matching. A traveling-wave electrode is designed to integrate with the III-V/Si hybrid MOS optical modulator under forward and reverse bias.

An optical modulator includes a relay substrate having signal conductor patterns that connect input signal terminals and signal electrodes of an optical modulation element and ground conductor patterns, and a housing that accommodates the optical modulation element and the relay substrate. Regarding at least one signal conductor pattern, the two ground conductor patterns sandwiching the signal conductor pattern are formed in an asymmetrical shape in a plan view in a rectangular connection area including a signal connection portion at which the signal conductor pattern and the input signal terminal are connected. The connection area is centered on the at least one signal conductor pattern in a width direction, and has a width equal to a distance to the nearest adjacent signal conductor pattern and a height equal to a distance from an end of the signal connection portion farthest from a signal input side to the signal input side.