Disclosed is a silicon photonics-based optical transmission apparatus. The apparatus includes an optical modulator chip of a ground-signal-ground (GSG) electrode array including two phase shifters for differential driving, a sub-substrate including a metal electrode of a periodic pattern to connect two ground metal electrodes to each other at a GSG electrode connected to each of the two phase shifters, and a solder bump having a same periodic pattern as the metal electrode of the sub-substrate to connect the ground metal electrodes of the optical modulator chip and the metal electrode of the periodic pattern of the sub-substrate.

Provided is a technique for reducing, using a simple circuit configuration, an amplitude difference between electric signals that are input to respective optical waveguide arms. An optical modulator includes: an optical demultiplexer that splits continuous wave light as received; first and second optical waveguide arms through which the continuous wave light as split propagates; an optical phase n shifter that introduces a phase shift of π to the continuous wave light as split; an optical multiplexer combines the continuous wave light propagating through the first and second optical waveguide arms; first and second signal electrodes that respectively input the electric signals to the first and second optical waveguide arms; a junction capacitance connected in shunt to at least one of the first and second signal electrodes; and a DC voltage source that applies a DC voltage to the junction capacitance.

An optical functional device equivalent to a 2×2 Mach-Zehnder optical switch is produced by forming two 3 dB couplers and input/output waveguides on a substrate. Two optical phase modulation paths are formed on corresponding waveguides between 3 dB couplers. A channel region having an opposite electric polarity is formed between source and drain regions, having the predetermined electric polarity, formed on the substrate. The optical phase modulation path is insulated from the surrounding area and disposed above the channel region. Additionally, a control electrode (i.e. a gate region) subjected to high-density doping is formed above the optical phase modulation path. By applying an electric voltage having the predetermined polarity to the control electrode, the source region, and the drain region, it is possible to generate hot carriers, in proximity to the optical phase modulation path, so as to accumulate charges and change a refractive index, thus setting a desired light-wave input/output path.

An optical integrated circuit includes: a mode conversion and branching section that launches light from a first optical waveguide to a second optical waveguide, converts light from the first optical waveguide into converted light, and launches the converted light to a third optical waveguide; an optical multiplexing and branching section that multiplexes lights from the second and third optical waveguides into one multiplexed light component, and branches the multiplexed light component into a light component to be input to a fourth optical waveguide and a light component to be input to a fifth optical waveguide; a phase modulation section that is provided in at least one of the fourth and fifth optical waveguides and modulates a phase of guided light; and an optical multiplexing section that multiplexes light components from the fourth and fifth optical waveguides into one light component.

In an embodiment, a phase shifter includes: a light input end; a light output end; a p-type semiconductor material, and an n-type semiconductor material contacting the p-type semiconductor material along a boundary area, wherein the boundary area is greater than a length from the light input end to the light output end multiplied by a core width of the phase shifter.

An optical waveguide device includes an intermediate layer, a thin-film LN layer including X-cut lithium niobate, and a buffer layer stacked on a substrate; an optical waveguide formed in the thin-film LN layer; and an electrode for driving. The intermediate layer is formed by an upper first intermediate layer and a lower second intermediate layer, the second intermediate layer having a permittivity that is smaller than a permittivity of the first intermediate layer.

Disclosed herein is a traveling-wave Mach-Zehnder modulator and method of operating same that advantageously exhibits a reduced optical insertion loss as compared with contemporary Mach-Zehnder structures. Such advantage comes at the modest expense of increased modulator length and increased RF loss.

An optical modulation device configured of a planar optical waveguide, includes: a light incidence unit which allows light to be incident on the planar optical waveguide; a Mach-Zehnder interferometer which includes a first optical splitter section branching the light incident on the light incidence unit, two arm portions guiding the light branched by the first optical splitter section, a phase modulation unit linearly disposed on each of the two arm portions, and a first optical coupler section combining the light guided from the two arm portions; a light launching unit which launches the light combined by the first optical coupler section from the planar optical waveguide; and a traveling-wave electrode which includes an input unit and an output unit, and applies a voltage to the phase modulation unit.

A light modulator according to the invention includes an optical waveguide formed of a material having an electro-optic effect, a buffer layer formed on the optical waveguide, and a pair of electrodes formed on the buffer layer, the width in the direction, in which the pair of electrodes are opposed to each other, of the buffer layer located on the side of the electrodes opposed to the optical waveguide is smaller than the width in the direction, in which the pair of electrodes are opposed to each other, of the buffer layer located on the optical waveguide side.

A method for adjusting the properties of a photonic circuit such that they fit with expected properties, the photonic circuit including a waveguide which includes a light propagation region, is provided. The method includes a step of modifying the refractive index of at least one zone of the region, the step being implemented by an ion implantation in the at least one zone. It extends to a waveguide the light propagation region of which has at least one zone with a refractive index modified by ion implantation in which the light remains confined, as well as a photonic circuit incorporating such a guide.