An optical transmitter includes an electro-optic modulator, a monitor circuit that monitors output light of the electro-optic modulator, and a processor that controls a bias voltage of the electro-optic modulator using a monitoring result of the monitor circuit, wherein the processor superimposes a first dither signal with a first frequency and a second dither signal with a second frequency different from the first frequency, onto one bias voltage in a time sharing manner, calculates a first control error based on a first component oscillating at the first frequency and a second control error based on a second component oscillating at the second frequency based on the monitoring result, and determines a control value for controlling the bias voltage using the first control error and the second control error.

An electro-optic modulator for a waveguide is presented. The electro-optic modulator includes a first semiconductor layer, a second semiconductor layer, a dielectric layer interposed between the second semiconductor layer and the first semiconductor layer and a coupling layer for coupling a guided mode of the waveguide to at least one of the first semiconductor layer and the second semiconductor layer. The electro-optic modulator is configured to induce a modulation on the guided mode of the waveguide by changing a refractive index in response to a voltage applied between the first semiconductor layer and the second semiconductor layer.

An optical waveguide device includes a slot groove formed in a substrate; a pair of electrodes disposed in the slot groove; an electro-optic polymer material in the slot groove; and a step portion formed at an outer side of the slot groove, in a length direction of the slot groove.

An optical modulator includes an optical waveguide through which signal light passes, a split unit that splits the signal light that passes through the optical waveguide, and a pair of phase shifters each of which shifts a phase of signal light that is split by the split unit. Each of the phase shifters includes an in-shifter waveguide through which the signal light passes, and a heater electrode that heats the in-shifter waveguide in accordance with a driving voltage. The in-shifter waveguide includes an inbound waveguide for inputting the signal light coming from the split unit, an outbound waveguide for outputting the signal light, a folded waveguide that connects the inbound waveguide and the outbound waveguide. The heater electrode is arranged in the vicinity of the inbound waveguide and the outbound waveguide.

Disclosed are a Mach-Zehnder interferometric optical modulator and a method for manufacturing the same. The modulator includes first and second lower clad layers, a core layer, an upper clad layer, a waveguide, and electrodes. The waveguide may include an input waveguide, a waveguide divider, branch waveguides, and a waveguide combiner. Each of the branch waveguides includes first and second connection regions connected to the waveguide combiner and the waveguide divider, respectively, and a phase shift region having a cross-section of a reverse mesa structure that has an upper width that is the same as widths of the first and second connection regions and a lower width that is smaller than the widths of the first and second connection regions.

A multi-section optical modulator and related method are disclosed wherein two waveguide arms traverse a plurality of successive modulating sections. A differential drive signal is applied separately to each waveguide arm of each modulating sections in synchronism with the transmission of light along the waveguide arms, effecting a dual differential driving of each section. By suitably selecting the number of modulating sections and the section length, a high modulation bandwidth and a high modulation efficiency may be achieved simultaneously for a given peak-to-peak voltage swing of the drive signal.

Chip technology for fabricating ultra-low-noise, high-stability optical devices for use in an optical atomic clock system. The proposed chip technology uses diamond material to form stabilized lasers, frequency references, and passive laser cavity structures. By utilizing the exceptional thermal conductivity of diamond and other optical and dielectric properties, a specific temperature range of operation is proposed that allows significant reduction of the total energy required to generate and maintain an ultra-stable laser. In each configuration, the diamond-based chip is cooled by a cryogenic cooler containing liquid nitrogen.

An optical modulators is disclosed. The optical modulator includes a substrate, an optical waveguide formed on the substrate, a signal electrode formed on the optical waveguide via a first buffer layer and applying a modulation signal to the optical waveguide, and a bias electrode formed on the optical waveguide via a second buffer layer and applying a DC bias to the optical waveguide, the first buffer layer and the second buffer layer are formed in such a way that either one of the first buffer layer and the second buffer layer covers an end surface of the other one of the first buffer layer and the second buffer layer at a boundary part of the first buffer layer and the second buffer layer. Accordingly, an optical modulator with high reliability can be provided.

An electro-optical device includes an optical waveguide and an upper electrode provided on the optical waveguide, the optical waveguide is formed by turning back on a plane, the upper electrode has adjacent parts by turning back the optical waveguide, and an upper layer higher than the upper electrode between the adjacent parts includes a metal layer. Alternatively, an electro-optic device includes a plurality of Mach-Zehnder optical waveguides, wherein the Mach-Zehnder optical waveguide includes a first optical waveguide and a second optical waveguide, a first upper electrode is provided on the first optical waveguide and a second upper electrode is provided on the second optical waveguide, and an upper layer higher than the first upper electrode and the second upper electrode between the first upper electrode and the second upper electrode includes a metal layer. An electro-optic device is capable of suppressing electrical crosstalk between components and seeking wide frequency band.

Disclosed is a plasmonic device (10), comprising: a substrate (11); and a dielectric layer (13) arranged between a base metal layer (12) and a structured metal layer (14) which form with respect to the substrate (11) a vertical stack of layers, wherein the structured metal layer (14) includes arranged in a horizontal direction an input structure (141) for enabling an input section (21), a waveguide structure (142) for enabling a plasmonic waveguide (22), and an output structure (143) for enabling an output section (23), wherein the input section (21) is configured to receive an optical input signal (31) and transmit input power (41) to the plasmonic waveguide (22), wherein the plasmonic waveguide (22) is configured to receive input power (41) from the input section (21) and transmit output power (43) to the output section (23), and wherein the output section (23) is configured to receive output power (43) from the plasmonic waveguide (22) and transmit an optical output signal (33).