An optical modulator includes a Mach-Zehnder interferometer including (i) a first optical waveguide including a first semiconductor junction diode, and (ii) a second optical waveguide including a second semiconductor junction diode. A semiconductor region connects the first and second semiconductor junction diodes such that a distance between the first and second optical waveguides is less than 2.0 μm for at least a portion of a longitudinal direction of the optical modulator. In another aspect, a method of modulating an optical signal includes splitting input light into first and second optical transmission paths; modulating a phase difference between light in the first optical transmission path and light in the second optical transmission path without applying a bias voltage through an impedance less than 100 ohm between the first and second optical transmission paths; and combining light that is output from the first and second optical transmission paths.

An optical modulator, that includes a Mach-Zehnder interferometer and three or more segments, generates an optical signal based on three or more electric signals transmitted in parallel. The three or more segments are provided in series along an optical path of the Mach-Zehnder interferometer and respectively shift a phase of light propagating through the optical path based on the three or more electric signals. A length of at least one of the three or more segments is different from lengths of the other segments. Optical path lengths from input ends of respective segments to input ends of corresponding next segments are the sae.

A waveguide structure for use in a balanced push-pull Mach Zehnder modulator. The waveguide structure comprises a plurality of layers. The layers comprise, in order: an insulating or semi-insulating substrate; an lower cladding layer; an waveguide core layer; and an upper cladding layer. The lower cladding layer, waveguide core layer, and upper cladding layer are etched to form: a signal waveguide and a ground waveguide, which are connected via the lower cladding layer; and a signal line and a ground line, each located adjacent to the respective waveguide, and each connected to the respective waveguide via one or more respective resistive structures connected in the plane of the lower cladding layer.

An optical waveguide element including a substrate, an optical waveguide formed on the substrate, and an electrode for controlling a light wave propagating through the optical waveguide, in which the optical waveguide and the electrode have an intersection in which the optical waveguide and the electrode intersect with each other, and at the intersection, the electrode has a multilayer structure including a plurality of metal layers made of a metal material, and a resin layer made of a resin material is formed between the electrode and the substrate.

Methods and systems for encoding multi-level pulse amplitude modulated signals using integrated optoelectronics are disclosed and may include generating a multi-level, amplitude-modulated optical signal utilizing an optical modulator driven by first and second electrical input signals, where the optical modulator may configure levels in the multi-level amplitude modulated optical signal, drivers are coupled to the optical modulator; and the first and second electrical input signals may be synchronized before being communicated to the drivers. The optical modulator may include optical modulator elements coupled in series and configured into groups. The number of optical modular elements and groups may configure the number of levels in the multi-level amplitude modulated optical signal. Unit drivers may be coupled to each of the groups. The electrical input signals may be synchronized before communicating them to the unit drivers utilizing flip-flops. Phase addition may be synchronized utilizing one or more electrical delay lines.

There is described an RF waveguide array. The array comprises a substrate comprising a plurality of optical waveguides, each waveguide being elongate in a first direction. An electrical RF transmission line array is located on a face of the substrate and comprises a plurality of signal electrodes and a plurality of ground electrodes, each electrode extending in the first direction. Each signal electrode is positioned to provide a signal to two respective waveguides. The ground electrodes include at least one intermediate ground electrode positioned between each pair of signal electrodes. Each intermediate ground electrode includes a portion extending into the substrate.

To provide an optical transmitter and an optical transmission method that can maintain the quality of an optical output signal in a wide wavelength range, an optical transmitter comprises: an optical modulator that includes an electrode and outputs an optical output signal obtained by modulating input light according to a drive signal applied to the electrode; a driver circuit that generates a drive signal and is connected to the optical modulator to apply a drive signal to one end of the electrode; a first element that is connected to the other end of the electrode and terminates the drive signal; and a controller that sets a first resistance value of the first element and a drive amplitude of the drive signal.

An interferometer comprises a plurality of waveguide branches comprising a plurality of bus waveguides and a plurality of photonic resonators. A first waveguide branch of the plurality of waveguide branches comprises a first photonic resonator coupled to a first bus waveguide. The first photonic resonator is disposed to couple and circle a first portion of an optical beam at the first photonic resonator to generate a first phase shift of the first portion of the optical beam, where the first phase shift is the same as a second phase shift of a second photonic resonator coupled to a second bus waveguide.

A silicon-based electro-optic modulator includes a substrate layer, an insulation layer, and an optical waveguide layer stacked sequentially, traveling wave electrodes disposed above the optical waveguide layer, and a metal grating structure periodically configured along the direction in which an electrical signal propagates in the traveling wave electrodes. The metal grating structure is disposed above the optical waveguide layer.

An electrical-optical modulator may include one or more optical waveguides to propagate one or more optical signals in a direction of propagation. An optical waveguide of the one or more optical waveguides may include a time delay section, a first modulation section preceding the time delay section in the direction of propagation, and a second modulation section following the time delay section in the direction of propagation. The first modulation section and the second modulation section may be configured to be associated with opposite modulation polarities, and the time delay section may be configured to delay a phase of the one more optical signals relative to the first modulation section. The electrical-optical modulator may include one or more signal electrodes to propagate one or more signals in the direction of propagation in order to modulate the one or more optical signals through electrical-optical interaction.