Abstract: A modulated light source includes an FP laser that emits light in a plurality of Fabry-Perot (FP) modes, a band-pass filter whose center wavelength can be modulated, a light reflector that selectively feeds only light having passed through the modulation filter back to the FP laser, and a wavelength adjustment mechanism that adjusts the center wavelength so as to coincide with one of the predetermined FP mode when the light fed back to the FP laser is used as seed light for stimulated emission of radiation to cause selective light emission at an oscillation wavelength.

Abstract: An optical resonator apparatus includes an optical resonator unit wherein ring optical resonators each including a first optical waveguide and a resonance wavelength adjustment electrode are coupled in cascade connection and round-trip lengths of the ring optical waveguides are different from each other and vary in order from an input side to an output side, and a controller that adjusts a resonance wavelength of each ring optical resonator in order beginning with the ring optical resonator provided at the most input side so as to match with an input light wavelength and, when an inter-channel occurs, adjusts the resonance wavelength of the first ring optical resonator from the input side so as to match with a second-matching input light wavelength and adjusts the resonance wavelengths of the second and succeeding ring optical resonators from the input side so as to match with the first-matching input light wavelength.

Abstract: In a method of manufacturing an optical device including an optical waveguide having a core, a cladding and a light input/output part through which a light beam is input or output, a substrate is prepared which is provided with a uniform thickness of single-crystalline film having its constituent atoms forming a diamond lattice structure and its surface being neither the (111) plane nor its equivalent planes. In the single-crystalline film, a precursor structure is formed which has a precursor of light input/output part. A mask is formed such as to expose the precursor with the remaining part covered. The structure is immersed into an alkaline solution for wet etching with the (111) planes used as etch-stop planes.

Abstract: An optical fiber guide that guides an optical fiber, the optical fiber guide includes a first substrate, and a guide groove that is formed on a main surface of the first substrate, the optical fiber being insertable from one end side of the guide groove, wherein the guide groove includes a positioning unit that forms a distal end portion of the guide groove, the positioning unit having a slide inclined surface that positions the optical fiber by sliding a distal-end inclined surface of the optical fiber in contact therewith.

Abstract: According to one embodiment, a semiconductor light-receiving element, includes a light-receiving part provided on a substrate and having a semiconductor multilayer structure of a circular outer shape, a optical input part formed of a peripheral portion of the semiconductor multilayer structure, and having a tapered front end, and a silicon-thin-line waveguide configured to couple light with the optical input part. The waveguide includes a linear part extending through the optical input part to an at least one area of an upper-side area and a lower-side area of the light-receiving part, and a spiral part connected to the linear part and formed in the at least one area.

Abstract: An optical element includes: a polarization splitter that splits light input from an input port into a first signal and a second signal according to a plane of polarization; a polarization rotator that rotates a plane of polarization of the second signal output from the polarization splitter by 90 degrees; a first optical coupler that combines the first signal output from the polarization splitter and the second signal output from the polarization rotator and splits the resultant signal into a third signal and a fourth signal with an equal amplitude; a phase controller that controls a phase of the third signal; and a second optical coupler that combines the third signal output from the phase controller and the fourth signal output from the first optical coupler and splits the resultant signal into a fifth signal and a sixth signal with an equal amplitude.

Abstract: An optical element includes: a first delayed interferometer; and a second delayed interferometer and a third delayed interferometer cascaded to the first delayed interferometer. The first delayed interferometer includes: a first optical coupler and a second optical coupler; a first waveguide between the first optical coupler and the second optical coupler; a second waveguide between the first optical coupler and the second optical coupler, the second waveguide being longer than the first waveguide; and a ring waveguide that is coupled to the first waveguide. A difference between a length of the first waveguide and a length of the second waveguide differs from a difference in lengths corresponding to a channel spacing by a length corresponding to a phase displacement caused by loading of the ring waveguide.

Abstract: A control method of an optical element, including light sources to emit lights having different wavelengths from each other, and ring modulators connected in cascade along a light waveguide, is disclosed. Each ring modulator includes a ring resonator, and a wavelength adjustment electrode to adjust a resonance wavelength in the ring resonator, wherein the lights from the light sources are multiplexed to enter the light waveguide. The method includes having a light source emit the light; adjusting power to the wavelength adjustment electrode in each ring modulator, to obtain a value of the power causing the resonance wavelength of the ring resonator, equivalent to the wavelength of the light emitted from the light source; obtaining a relationship between the light sources and the values of the power corresponding to the ring modulators; and selecting the ring modulators corresponding to the light sources based on the relationship.

Abstract: There is provided a semiconductor laser module with a semiconductor laser chip, in which a first optical waveguide is formed, flip-chip mounted on a silicon substrate with a mesa structure in which a second optical waveguide is formed. The optical axes of the first optical waveguide and the second optical waveguide make a specified angle with lines perpendicular to the respective cleavage planes. Alignment marks are provided on the silicon substrate and the semiconductor laser chip at at least two positioning locations to enable mounting of the semiconductor laser chip by passive alignment. The mounting position is decided so that laser light emitted in a direction of the optical axis of the first optical waveguide and refracted at the emission surface, is refracted at the incident surface of the second optical waveguide and becomes incident in the direction of the optical axis of the second optical waveguide.

Abstract: In a method of manufacturing an optical device including an optical waveguide having a core, a cladding and a light input/output part through which a light beam is input or output, a substrate is prepared which is provided with a uniform thickness of single-crystalline film having its constituent atoms forming a diamond lattice structure and its surface being neither the (111) plane nor its equivalent planes. In the single-crystalline film, a precursor structure is formed which has a precursor of light input/output part. A mask is formed such as to expose the precursor with the remaining part covered. The structure is immersed into an alkaline solution for wet etching with the (111) planes used as etch-stop planes.