Improved dither detection, measurement, and voltage bias adjustments for an electro-optical modulator are described. The electro-optical modulator generally includes RF electrodes and phase heaters interfaced with semi-conductor waveguides on the arms of Mach-Zehnder interferometers, where a processor is connected to output a bias tuning voltage to the electro-optical modulator for controlling optical modulation. A variable gain amplifier (VGA) can be configured with AC coupling connected to receive a signal from a transimpediance amplifier (TIA) that is configured to amply a photodetector signal from an optical tap that is used to measure an optical signal with a dither signal. The analog to digital converter (ADC) can be connected to receive output from the VGA. The processor can be connected to receive the signal from the ADC and to output the bias tuning voltage based on evaluation of the signal from the tap.

A combinatorial optimization problem processing device is for associating a combinatorial optimization problem having N elements with an Ising model to process the combinatorial optimization problem. The combinatorial optimization problem processing device includes: a 1×2 Mach-Zehnder optical modulator that receives a polarized clock pulse train; an optical interference circuit that receives polarized clock pulse trains that were modulated by the Mach-Zehnder optical modulator; an optical coupler that couples output of the optical interference circuit with an initialization optical pulse train that creates a neutral state with respect to interactions between the elements; and a modulation signal generator that performs waveform shaping on an electrical signal obtained by photoelectrically converting an output signal of the optical coupler, generates a modulation signal for the Mach-Zehnder optical modulator, and externally outputs a monitor signal that represents a solution to the optimization problem. The optical interference circuit repeatedly allows a predetermined interaction in the Ising model to occur from the neutral state at a period corresponding to the N pulses of the polarized clock pulse train.

An optical device includes a rib waveguide that is a thin-film lithium niobate (LN) crystal, a buffer layer that is laminated on the rib waveguide, and an electrode that applies voltage to the rib waveguide. The buffer layer includes a thick-film part that is laminated on a rib of the rib waveguide, and thin-film parts that are laminated on slabs of the rib waveguide, where the slabs are located on both sides of the rib, and that have smaller thicknesses than a thickness of the thick-film part.

An optical modulator includes a plurality of optical modulation units having a Mach-Zehnder type optical waveguide consisting of two optical waveguides and a high-frequency line pair arranged along the two optical waveguides and consisting of two signal electrodes for applying a pair of differential high-frequency signals, and a plurality of high-resistance conductive films are provided between adjacent high-frequency line pairs separated from the high-frequency line pair.

A monolithic integrated electro-optical phase modulator, a Mach-Zehnder modulator including one or more of the phase modulators, and method for fabricating the phase modulator by III-V-on-silicon semiconductor processing are provided. The phase modulator includes a silicon-based n-type substrate base layer, and a III-V n-type ridge waveguide for propagating light, wherein the ridge waveguide protrudes from and extends along the n-type substrate base layer. Further, the phase modulator includes one or more insulating layers provided on the ridge waveguide, wherein the one or more insulating layers have together a thickness of 1-100 nm, and a silicon-based p-type top cover layer provided on the one or more insulating layers at least above the ridge waveguide.

A semiconductor device includes an electrode which is arranged on an organic material with an insulation film interposed therebetween and which does not easily peel away from the organic material along with the insulation film. An insulation film in a region including pad portions of a phase shift electrode and a modulation electrode has openings at the centers of the pad portions of the phase shift electrode and the modulation electrode, the edge portions of which are formed on the phase shift electrode and the modulation electrode. In this way, the adjoining edges of the phase shift electrode and modulation electrode and the insulation film are all covered by the insulation film so as not to be exposed to the atmosphere. By covering the cracks that occur in the insulation film in the production process with the insulation film made of SiO.sub.2, SiN.sub.X, SiON.sub.X or the like, an organic solvent such as acetone or ethanol used in the process can be prevented from seeping in between the insulation film and the organic material through the cracks in the insulation film.

An optical transmitter includes: a modulator, square law detector, and a processor. The modulator generates an optical signal indicating transmission data. The square law detector detects an intensity of the optical signal using a photodetector and output first intensity data indicating the detected intensity. The processor calculates, based on the transmission data, an electric field of the optical signal generated by the modulator by using parameters pertaining to a state of the modulator. The processor calculates second intensity data indicating the intensity of the optical signal based on the calculated electric field. The processor updates the parameters so as to reduce a difference between the first intensity data and the second intensity data. The processor controls the state of the modulator based on the parameters.

Methods and systems for redundant light sources by utilizing two inputs of an integrated modulator are disclosed and may include: an optoelectronic transmitter integrated in a semiconductor die with first and second laser sources coupled to the semiconductor die, said optoelectronic transmitter comprising an optical modulator with a first input waveguide coupled to the first laser source and second input waveguide coupled to the second laser source, the optoelectronic receiver being operable to: configure the first laser source to provide an optical signal to the first input of the optical modulator; and if the first laser source does not provide an optical signal, configure the second laser source to provide an optical signal to the second input of the optical modulator. The first laser source may be optically coupled to the first input waveguide and the second laser source optically coupled to the second input waveguide using grating couplers.

To effectively prevent the acceleration of the drift phenomenon generated by the application of a high electric field to a substrate through a bias electrode in a waveguide type optical element. A waveguide type optical element includes a substrate (100) having an electro-optic effect, two optical waveguides (104 and 106) disposed on a surface of the substrate, a non-conductive layer (120) which is disposed on the substrate and is made of a material having a lower dielectric constant than the substrate, and a control electrode (150) which is disposed on the non-conductive layer and is intended to generate a refractive index difference between the two optical waveguides by respectively applying electric fields to the two optical waveguides, and the non-conductive layer is constituted of a material which includes silicon oxide, an oxide of indium, and an oxide of titanium and has a ratio between a molar concentration of the titanium oxide and a molar concentration of indium oxide of 1.2 or more, and a voltage generating an electric field of 1 V/μm or more in the substrate is applied to the control electrode.

Apparatus, circuits and methods for reducing mismatch in an electro-optic modulator are described herein. In some embodiments, a described optical includes: a splitter configured for splitting an input optical signal into a first optical signal and a second optical signal; a phase shifter coupled to the splitter; and a combiner coupled to the phase shifter. The phase shifter includes: a first waveguide arm configured for controlling a first phase of the first optical signal to generate a first phase-controlled optical signal, and a second waveguide arm configured for controlling a second phase of the second optical signal to generate a second phase-controlled optical signal. Each of the first and second waveguide arms includes: a plurality of straight segments and a plurality of curved segments. The combiner is configured for combining the first and second phase-controlled optical signals to generate an output optical signal.