Abstract: An optical module has a structure for reducing the stress applied to a package. The optical module is structured so that an end face of a waveguide (37) of a planar lightwave circuit (30) is joined to a plurality of packages (40) storing therein optical elements so that the waveguide is optically coupled to the optical elements. The optical module includes a housing (3) storing therein a planar lightwave circuit and a plurality of packages in which an upper face of a protrusion (270) formed in the bottom section is fixed to the planar lightwave circuit (30). Each of the plurality of packages (40) is electrically connected to an electric part (22) provided in the housing (3) via flexible printed circuits (271a, 271b).

Abstract: An optical modulator having a high stability is provided. In the optical modulator according to the present invention, a phase modulation by an electro-optic effect is made on an optical substrate of an electro-optic material while the setting of an operating point by a thermal-optic effect is made on a planar lightwave circuit (PLC) substrate of quartz, silicon, or the like. Such configuration can suppress the influence of thermal drift or the like because no heat is applied directly to the optical substrate of the electro-optic material. In addition, breakage and warpage of the substrate due to heat are also mitigated. Further, quartz used for the PLC has a low thermal conductivity, approximately one-fifth of that of the LN substrate (approximately 1 W/(m·K)), and therefore, a desired phase difference can be maintained with a low power consumption, and thus, the operating point becomes stabilized.

Abstract: An optical modulator having a high stability is provided. In the optical modulator according to the present invention, a phase modulation by an electro-optic effect is made on an optical substrate of an electro-optic material while the setting of an operating point by a thermal-optic effect is made on a planar lightwave circuit (PLC) substrate of quartz, silicon, or the like. Such configuration can suppress the influence of thermal drift or the like because no heat is applied directly to the optical substrate of the electro-optic material. In addition, breakage and warpage of the substrate due to heat are also mitigated. Further, quartz used for the PLC has a low thermal conductivity, approximately one-fifth of that of the LN substrate (approximately 1 W/(m·K)), and therefore, a desired phase difference can be maintained with a low power consumption, and thus, the operating point becomes stabilized.

Abstract: Two AWG circuits are integrated while preventing degradation in quality of a multiplexing/demultiplexing function. An arrayed waveguide grating circuit includes: a first slab waveguide (52) connected to a first input waveguide (51a) and second output waveguides (55b); a second slab waveguide (54) connected to first output waveguides (55a) and a second input waveguide (51b); and an array waveguide (53) connecting the first slab waveguide (52) and the second slab waveguide (54), wherein the input waveguides (51a, 51b) are connected to the slab waveguides (52, 54) at an interval of 1.5× from the outermost second output waveguide out of the second output waveguides (55a, 55b) connected at an interval x depending on a wavelength.

Abstract: An optical module has a structure for reducing the stress applied to a package. The optical module is structured so that an end face of a waveguide (37) of a planar lightwave circuit (30) is joined to a plurality of packages (40) storing therein optical elements so that the waveguide is optically coupled to the optical elements. The optical module includes a housing (3) storing therein a planar lightwave circuit and a plurality of packages in which an upper face of a protrusion (270) formed in the bottom section is fixed to the planar lightwave circuit (30). Each of the plurality of packages (40) is electrically connected to an electric part (22) provided in the housing (3) via flexible printed circuits (271a, 271b).

Abstract: Two AWG circuits are integrated while preventing degradation in quality of a multiplexing/demultiplexing function. An arrayed waveguide grating circuit includes: a first slab waveguide (52) connected to a first input waveguide (51a) and second output waveguides (55b); a second slab waveguide (54) connected to first output waveguides (55a) and a second input waveguide (51b); and an array waveguide (53) connecting the first slab waveguide (52) and the second slab waveguide (54), wherein the input waveguides (51a, 51b) are connected to the slab waveguides (52, 54) at an interval of 1.5× from the outermost second output waveguide out of the second output waveguides (55a, 55b) connected at an interval x depending on a wavelength.

Abstract: By reducing the number of PD arrays, and by simplifying the configuration of an optical power monitor in a WDM system, a miniaturized, cost reduced optical signal monitoring apparatus, optical system or optical signal monitoring method is provided. An optical power monitor 1 has an optical switch 30 having four input ports 31, a DMUX 2 having 48 output ports, and six CSP type PD array modules 50 each including an 8-channel PD array. The output port 32 of the optical switch 30 having four switchable input ports 31 is optically connected to the input port 21 of the AWG 20. The 48 output ports 22 of the AWG 20 are each optically connected to photosensitive surfaces 53 of the individual PDs included in the CSP type PD array modules 50. The CSP type PD array modules 50 are mounted on the end face of the AWG 20.

Abstract: An arrayed waveguide grating type optical multiplexer/demultiplexer circuit in which wavelength dispersion is reduced. An input wave guide (1), a first slab waveguide (2), an arrayed waveguide (3), a second slab waveguide (4) and an output waveguide (5) are connected sequentially. Furthermore, a parabola waveguide (6) is provided between the input waveguide (1) and the first slab waveguide (2), and a taper waveguide (7) is provided between the second slab waveguide (4) and the output waveguide (5). A parabola waveguide length Z0 exists in a range Za,0=Z0=Zp,0 determined by a parabola waveguide length Za,0 where the ratio of absolute amplitude between the main peak and the first side peak in the field distribution of far-field of the parabola waveguide (6) has an upper limit of 0.217, and a parabola waveguide length Zp,0 where the relative phase of the main peak and the first side peak in the field distribution of far-field has a lower limit of 3.14 radian.

Abstract: An optical multiplexer is equipped with at least one input channel optical waveguide provided on an optical waveguide substrate, a first slab optical waveguide, a channel optical waveguide array formed from a plurality of optical waveguides having a prescribed waveguide length, a second slab optical waveguide and at least one output channel optical waveguide sequentially connected in a tandem arrangement; and phase adjustment to achieve the same phase distribution in the channel optical waveguide array.

Abstract: A part of a wavelength division multiplexed optical signal output from a multiplexing area is extracted as a check signal, and then the extracted signal is guided to a multiplexing area. A reentered check signal is detected at a facet located opposite a facet from which the check signal has been reentered, and the state of the detected check signal is determined. Furthermore at need, on the basis of the result of the determination, a control signal is output that controls operations of a plurality of optical signals input to the multiplexing area.

Abstract: The object of the present invention is to provide a full-mesh optical wavelength division multiplexing transmission network device which is capable of exhibiting excellent communication quality and being mass produced, by reducing the accumulation number of coherent crosstalk lights, without any modification of constituent components constituting the conventional one. In the full-mesh optical wavelength division multiplexing transmission network device, provided is an N×N wavelength multi/demultiplexer having a periodic wavelength demultiplexing property in input/output combination, which performs input/output from/to first and second I/O port groups for optical signals and allows lightwaves traveling in opposite directions not to interfere with each other within the circut, thus reducing the accumulation number of coherent crosstalk lights in WDM wavelength lights and improving S/N of a received light.

Abstract: The arrayed waveguide grating (AWG) is a known prior art optical multiplexer used in WDM optical communication systems. In the prior art flat-type AWG, the pulse waveform is distorted due to the dispersion in the AWG itself, and this forms a serious problem that makes it impossible to use the AWG as a multiplexer.

Abstract: A part of a wavelength division multiplexed optical signal output from a multiplexing area is extracted as a check signal, and then the extracted signal is guided to a multiplexing area. A reentered check signal is detected at a facet located opposite a facet from which the check signal has been reentered, and the state of the detected check signal is determined. Furthermore at need, on the basis of the result of the determination, a control signal is output that controls operations of a plurality of optical signals input to the multiplexing area.

Abstract: A frequency stabilized laser using an integrated external cavity, comprising a semiconductor laser diode and an optical waveguide installed on the same substrate, and having an optically induced grating formed in the optical waveguide suppresses mode hopping due to a temperature change to stabilize the oscillation frequencies of the laser. A material having a refractive index temperature coefficient opposite in sign to the refractive index temperature coefficient of the semiconductor laser diode is installed on that portion of the optical waveguide between the semiconductor laser diode and the optically induced grating which has been formed by removing an upper cladding and a core, or removing the upper cladding, the core, and a lower cladding.

Abstract: In a light waveguide circuit including a plurality of waveguides having different length, a material (10) having a temperature coefficient of a refractive index including a symbol different from that of a temperature coefficient of an effective refractive index of the waveguide (4) is charged into a groove (12) formed by removing the upper clad and the core from the waveguide (4), or a groove (12) formed by removing the upper clad, the core and the lower clad from the waveguide (4). A difference in length of the removed portions between adjacent waveguides is proportional to a difference in length of the waveguides which were not removed and remained.

Abstract: This planar lightwave circuit includes a buried layer formed in a region between at least two cores branching from a branching point to decrease in thickness as the spacing between the cores increases with an increase in distance from the branching point. The planar lightwave circuit is designed to suppress scattering of light signals at the branching point.

Abstract: The present invention provides a wavelength division multiplexing filter that requires lower costs, a smaller size, and a smaller amount of fiber routing operations. According to the present invention, a first module constitutes a first filter. A second module constituting a second filter is produced by connecting together circuits identical in number to a plurality of output ports of the first module, the circuits each comprising a combination of directional couplers and Bragg gratings both formed of silica-based-glass waveguides, the circuits each having a wavelength selection characteristic so as to correspond to each of the output ports. The second module is connected to the first module via an 8-fiber ribbon to simplify the integration and connection of the circuits.