Abstract: An optical module includes an optical semiconductor chip having a first surface that includes a laser beam irradiation region and a cleavage region, an optical fiber optically coupled to the first surface, and a support member having a second surface bonded to the first surface, and configured to support the optical fiber. The optical semiconductor chip has an optical signal input and output part located in the cleavage region, and the second surface is bonded to the first surface within the cleavage region.

Abstract: An optical device includes a rib optical waveguide that is a thin-film lithium niobate (LN) crystal formed of a thin-film LN substrate, and a buffer layer that is laminated on the optical waveguide. The optical device further includes an electrode that is laminated on the buffer layer, and sub electrodes that are arranged parallel to the electrode on the buffer layer, and attract a charge in the optical waveguide in accordance with electrification.

Abstract: A waveguide element includes a first waveguide and a second waveguide. The first waveguide includes a first main rib and a first slab that has a smaller thickness than that of the first main rib and in which a slab mode of light propagates. The second waveguide includes a second main rib that is optically coupled with the first main rib and in which the light propagates, a second slab that has a smaller thickness than that of the second main rib, that is optically coupled with the first slab, and in which the slab mode propagates, and a side rib that has a larger thickness than that of the second slab. The slab mode that propagates through the second slab transitions to the side rib in accordance with travel of the light that propagates in the first main rib and the second main rib.

Abstract: A tap coupler includes a mode generation unit, a separation unit, and an output unit. The mode generation unit generates, in accordance with a discontinuous portion disposed on a travelling path of signal light that is propagating, a first mode of the signal light and a second mode that is different from the first mode. The separation unit separates, when the first mode and the second mode are input from the mode generation unit, the first mode and the second mode. The output unit outputs branch light in accordance with a transition of the second mode received from the separation unit.

Abstract: An optical device includes an optical waveguide that is a rib type and that is formed of a thin film lithium niobate (LiNbO3: LN) substrate using a thin film LN crystal, and a buffer layer that is laminated on the optical waveguide. Furthermore, the optical device includes an electrode that is laminated on the buffer layer and that applies a voltage to the optical waveguide, and a gettering site that is disposed parallel to the optical waveguide and that traps an electric charge inside the optical waveguide.

Abstract: 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.

Abstract: A wavelength filter includes a first filter circuit and a second filter circuit. The first filter circuit that has a passband that is obtained from a vernier effect by connecting, in series, a plurality of ring resonators each having a different transmission wavelength interval and that is within a gain band of an optical amplifier, and that passes, from the gain band, light at a selected wavelength and light that has a wavelength in a recursive mode and that is produced on a short wavelength side or a long wavelength side of the selected wavelength. The second filter circuit is connected to the first filter circuit in series and suppresses the light at the wavelength in the recursive mode from the light passing through the first filter circuit.

Abstract: A disclosed semiconductor photodetector includes a first semiconductor layer having a first refractive index and a first band gap; a second semiconductor layer formed on the first semiconductor layer, the second semiconductor layer having a second refractive index and a second band gap; a first electrode; and a second electrode. The second refractive index is greater than the first refractive index, and the second band gap is smaller than the first band gap. The first semiconductor layer includes a p-type first region, an n-type second region, and a non-conductive third region between the first region and the second region. The second semiconductor layer includes a p-type fourth region in ohmic contact with the first electrode, an n-type fifth region in ohmic contact with the second electrode, and a non-conductive sixth region between the fourth region and the fifth region.

Abstract: An optical device includes a thin film Lithium Niobate (LN) layer, a first optical waveguide, and a second optical waveguide. The thin film LN layer is an X-cut or a Y-cut LN layer. The first optical waveguide is an optical waveguide that is formed on the thin film LN layer along a direction that is substantially perpendicular to a Z direction of a crystal axis of the thin film LN layer. The second optical waveguide is an optical waveguide that is routed and connected to the first optical waveguide. At least a part of a core of the first optical waveguide is made thicker than a core of the second optical waveguide.

Abstract: An optical device has a first photonic waveguide provided on a substrate, a second photonic waveguide provided on the substrate and extending side by side with the first photonic waveguide, and a looped waveguide continuously connecting the first photonic waveguide and the second photonic waveguide on the substrate, wherein a width of at least one of the first photonic waveguide or the second photonic waveguide varies continuously along an optical axis, between a first position located at a side opposite to the looped waveguide and a second position connected to the looped waveguide, and wherein cross sections of the first photonic waveguide and the second photonic waveguide are congruent at the second position, and are incongruent at the first position.

Abstract: In an optical transmitter having an electro-optic modulator with first child MZI and a second child MZI nested to form a parent MZI, and a processor that controls the bias voltages of electro-optic modulator. In the first section of a control loop, the processor simultaneously superimposes different dither signals onto the first bias voltage of the first child MZI and 1.0 the second bias voltage of the second child MZI, and extracts the first phase error information for the first child MZI and the first-round third phase error for the parent MZI from a first monitoring result. In the second section of the control loop, the processor simultaneously superimposes different dither signals onto the first and second bias voltages, and extracts the second phase error information for the second child MZI and the second-round third phase error for the parent MZI from a second monitoring result.

Abstract: An optical device includes an optical waveguide, a buffer layer that is layered on the optical waveguide, and an electrode that is arranged on a surface of the buffer layer that is layered in a part near the optical waveguide and that applies an electric signal to the optical waveguide. The optical device further includes a slit that is formed in the buffer layer, that extends from the surface of the buffer layer to a vicinity of the optical waveguide, and that is filled with part of the electrode.

Abstract: An optical device includes an optical waveguide, a buffer layer that is layered on the optical waveguide, and an opening that is formed at least in the buffer layer above a part near a side surface of the optical waveguide. The optical device further includes an electrode that is layered in the opening and that is configured to apply a signal to the optical waveguide and a silicon layer that is layered on the buffer layer excluding the opening.

Abstract: An optical device includes an X-cut substrate, and a first waveguide and a second waveguide each being formed on the substrate and having a folding structure. The optical device includes a first signal electrode to generate a first electric field, and a second signal electrode to generate a second electric field with a reverse phase as compared to the first field. The first waveguide includes a first waveguide on an outward side to which the first field is applied from the first signal electrode, and a first waveguide on a return side to which the second field is applied from the second signal electrode. The second waveguide includes a second waveguide on the outward side to which the first field is applied from the first signal electrode, and a second waveguide on the return side to which the second field is applied from the second signal electrode.

Abstract: An optical device includes a silicon substrate, a waveguide formed of a thin film that is laminated on the silicon substrate and that is made of a perovskite oxide with a large electro-optic effect as compared to lithium niobate, and a cladding layer that covers the waveguide. Further, the optical device includes ground electrode that has a ground potential and a signal electrode that is arranged at a position facing the ground electrode and that applies driving voltage to the waveguide.

Abstract: An optical module includes an optical semiconductor chip including a first electrode pad, a second electrode pad, and a third electrode pad arranged between the first electrode pad and the second electrode pad, a wiring substrate on which the optical semiconductor chip is flip-chip mounted, including a fourth electrode pad, a fifth electrode pad, and a sixth electrode pad arranged between the fourth electrode pad and the fifth electrode pad, a first conductive material connecting the first electrode pad with the fourth electrode pad, a second conductive material connecting the second electrode pad with the fifth electrode pad, a third conductive material arranged between the first conductive material and the second conductive material, connecting the third electrode pad with the sixth electrode pad, and a resin provided in an area on the second conductive material side of the third conductive material between the optical semiconductor chip and the wiring substrate.

Abstract: An optical transmitter device includes a modulator of the Mach-Zehnder type that modulates the optical signal from an emitter and outputs modulated signals; and a phase controller that controls the phase difference of the modulator according to a setting phase amount. The device includes a controller, a sweeper, and an estimator. The controller controls the bias current of the emitter so that the power of the modulated signals detected at the output stage of the modulator during the optical shutdown becomes the target value during the optical shutdown. After the bias current is controlled, the sweeper performs constant-period sweeping of the phase of the modulator. The estimator estimates, while sweeping the phase, the transmission characteristics of the modulator from the power of the optical signal detected at the input stage of the modulator; and, from the estimated characteristics, calculates the optimum phase amount to be set in the phase controller.

Abstract: An optical transmission apparatus includes an emitter that emits an optical signal in accordance with a bias current, and a Mach-Zehnder optical modulator that optically modulates the optical signal in accordance with an electrical signal. The optical modulator includes a detector that detects a temperature inside the optical modulator, and a controller that, when detecting activation of a power supply, controls the temperature inside the optical modulator such that the temperature detected by the detector reaches a target temperature.

Abstract: An optical waveguide device that is implemented between a slot waveguide and a rectangular waveguide includes: a tapered portion and a separation portion. The tapered portion includes first and second cores that are respectively coupled to cores of the slot waveguide and formed in parallel each other. The separation portion includes third and fourth cores that are respectively coupled to the first and second cores. Cross-sectional areas of the first and second cores are substantially equal each other at an input end. The cross-sectional area of the first core is larger than that of the second core at an output end. A shape of a cross section of the first core changes continuously between the input end and the output end in the tapered portion. A spacing between the third core and the fourth core is continuously extended in the separation portion.

Abstract: An optical device includes an optical waveguide that is a projected section and that is disposed at a predetermined portion on a thin film substrate, a buffer layer that is formed on the thin film substrate and the optical waveguide, and an electrode that is formed on the buffer layer and that applies a voltage to the optical waveguide. The electrode covers a step portion of the buffer layer formed on side walls of the optical waveguide.