Abstract: This optical waveguide is provided with a slab waveguide in which a grating is formed, an arrayed waveguide connected to a position where a constructive interference portion of a self-image of the grating is formed, and a refractive index change region which is formed between the slab waveguide and the arrayed waveguide, in which an average value of a refractive index in a refractive index distribution in a direction substantially vertical to a light propagation direction is averagely increased from the slab waveguide toward the arrayed waveguide, and in which an average value of the refractive index in a refractive index distribution in a direction substantially parallel to the light propagation direction is increased at a central axis of the arrayed waveguide.

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: A category setting part sets a type of a decoded image based on characteristics of the decoded image which are fineness of the decoded image and an intensity of movement of the decoded image. A code amount setting part sets a target code amount of an output image based on the type of the decoded image. A quantization step value setting part sets a quantization step value of the output image based on the target code amount of the output image. A transcoder can set the target code amount of the output image depending on fineness of the decoded image. The transcoder can distribute the target code amount of the output image to a reference image and a predicted image depending on the intensity of movement of the decoded image.

Abstract: A digital transmission system includes at least a client device and a transmission device, and rate-adjusts the client signal transmitted from the client device to the transmission device before accommodating/multiplexing the signal in a frame. The transmission device includes a rate adjusting unit and a frame processing unit. The rate adjusting unit encapsulates the client signal by using a predetermined frame structure, inserts an idle pattern if necessary, and performs rate adjustment into the bit rate which can be contained in the frame. The frame processing unit accommodates/multiplexes the signal after the rate adjustment. The digital transmission system inserts a bit string of the client signal directly in a payload area of the digital frame, or accommodates and multiplexes it. Alternatively, a specific pattern is accommodated in the payload area, or accommodated and multiplexed after performing a reversible digital signal processing.

Abstract: An APD is provided with the semi-insulating substrate, a first mesa having a first laminate constitution in which a p-type electrode layer, a p-type light absorbing layer, a light absorbing layer with a low impurity concentration, a band gap inclined layer, a p-type electric field control layer, an avalanche multiplier layer, an n-type electric field control layer, and an electron transit layer with a low impurity concentration are stacked in this order on a surface of the semi-insulating substrate, a second mesa having an outer circumference provided inside an outer circumference of the first mesa as viewed from the laminating direction and having a second laminate constitution in which an n-type electrode buffer layer and an n-type electrode layer are stacked in this order on a surface on the electron transit layer side, and a depletion control region that is provided in layers on the second mesa side relative to the p-type electric field control layer, formed in an encircling portion provided inside an out

Abstract: A low-cost optical module with highly consistent properties. The optical module includes, in a housing, an optical waveguide array, an optical functional element array, lens optics using one or a plurality of lenses for optically coupling the optical waveguide array and the optical functional element array, and a mirror disposed so as to convert the propagation direction of optical beams transmitted by the lens optics such that the optical beams are incident on the optical incidence ports of the optical functional element array. The optical functional element array is affixed to the housing, and the angle of the mirror is fixed in place after the angle of the mirror is adjusted such that the optical waveguide array and the optical functional element array are optically coupled.

Abstract: An APD is provided with a semi-insulating substrate, a first mesa having a first laminate constitution in which a p-type electrode layer, a p-type light absorbing layer, a light absorbing layer with a low impurity concentration, a band gap inclined layer, a p-type electric field control layer, an avalanche multiplier layer, an n-type electric field control layer, and an electron transit layer with a low impurity concentration are stacked in this order on a surface of the semi-insulating substrate, a second mesa having an outer circumference provided inside an outer circumference of the first mesa as viewed from the laminating direction and having a second laminate constitution in which an n-type electrode buffer layer and an n-type electrode layer are stacked in this order on a surface on the electron transit layer side of the first mesa, and in the APD, a total donor concentration of the n-type electric field control layer is lower than a total acceptor concentration of the p-type electric field control laye

Abstract: An arrayed waveguide grating optical multiplexer/demultiplexer according to the present invention including an input channel waveguide, an input slab waveguide, an arrayed waveguide, a polarization dependence eliminating means, an output slab waveguide, a temperature compensating means, and an output channel waveguide is characterized in that the temperature compensating means compensates for the temperature dependence of the optical path lengths in the channel waveguides of the arrayed waveguide, and the polarization dependence eliminating means eliminates the temperature dependence and the polarization dependence of the arrayed waveguide grating optical multiplexer/demultiplexer at the same time.

Abstract: In an optical component configured to fix to a mount an optical device chip in which a plurality of waveguide type optical devices having different thermal expansion coefficients are butt-jointed, deterioration in reliability due to thermal stress is suppressed. The optical component (300) comprises an optical device chip (310) including an LN waveguide (311), a first PLC waveguide (312) connected to an end of the LN waveguide (311), a second PLC waveguide (313) connected to the other end of the LN waveguide (311), and a fiber alignment member (314) connected to the first PLC waveguide (312), a mount (320) on which the optical device chip (310) is mounted, and optical fibers (330) aligned to the fiber alignment member (314).

Abstract: An output rate controller has a TS packet buffer, a maximum value increase detector, a minimum value decrease detector and an output controller. The TS packet buffer accumulates input packets. The maximum value increase detector detects an increasing trend of the maximum number of packets being accumulated in the TS packet buffer within a fixed time period. The minimum value decrease detector detects a decreasing trend of the minimum number of packets being accumulated in the TS packet buffer within a fixed time period. The output controller sets a higher output rate of packets being accumulated in the TS packet buffer if an increasing trend has been detected by the maximum value increase detector, and sets a lower output rate of packets being accumulated in the TS packet buffer if a decreasing trend has been detected by the minimum value decrease detector.

Abstract: A synchronization signal generator of a decoder adds a predetermined value to a time value, and outputs a synchronization signal when the added time value coincides with a reproducing time value in a frame.

Abstract: An image processing device carries out processing in a processing unit of 3-blocks. Data of 192(=64×3)-pixels is required in the processing of 3-blocks. This is an amount of data corresponding to 16-cells. When 3-blocks and 16-cells are arranged along an scanning direction of an image, both ends of them in the scanning direction are aligned.

Abstract: According to the present invention, as shown in FIG. 5(a), when a signal for clock recovery ED is generated, which is formed by alternately generating enable periods EN having a ratio (N/M) of N clocks' client data to M clocks' line data and disable periods D1 to D4, a phase of the disable period D2 is advanced by a phase corresponding to the disable period (such as one clock period) during the enable period with reference to phase information added to the signal for clock recovery ED as shown in FIG. 5(c) when a stuff pulse in the line data is detected as indicated by the symbol m0 in FIG. 5(b), thereby generating the signal for clock recovery ED.

Abstract: A semiconductor optical modulator that includes a first semiconductor optical waveguide having a laminated structure including a core layer, a first clad layer, a second clad layer, and a barrier layer, the first clad layer and the second clad layer being disposed below and above the core layer, the barrier layer being inserted between the second clad layer and the core layer; a second semiconductor optical waveguide having a laminated structure in which the second clad layer has a p-type semiconductor penetrating locally through a n-type semiconductor in a laminated direction in the laminated structure of the first semiconductor optical waveguide; a first electrode connected to the first clad layer of the first semiconductor optical waveguide; and a second electrode electrically connecting the second clad layer of the first semiconductor optical waveguide and the p-type semiconductor of the second clad layer of the second semiconductor optical waveguide.

Abstract: A technique that does not increase the circuit size, does not make the circuit design and manufacturing difficult, and can reduce insertion loss when light enters from a slab waveguide toward an arrayed waveguide or when the light enters from the arrayed waveguide toward the slab waveguide. An optical waveguide provided with a slab waveguide in which a grating is formed therein at a distance from an end, and an arrayed waveguide whose end is connected to an end of the slab waveguide at a position where a constructive interference portion of a self-image of the grating is formed.

Abstract: A wavelength selection switch that includes an optical component for adjusting an optical path with an image magnification of M that is provided between a second imaging position and a mirror array. Therefore, it is possible to provide a small wavelength selection optical switch with a short optical path length that is capable of reducing the focal length of each of a first lens and a second lens to 1/M while maintaining the structure of the spectral element, the fiber array, and the mirror array according to the related art. Since the optical path length is reduced, it is possible to reduce the number of reflecting mirrors used to convert an optical path and thus reduce the size of a housing. Therefore, it is possible to reduce manufacturing costs.

Abstract: In the present invention, unlike a conventional circuit, discrimination is not made by integrating a logical code that includes “0” and “1” to some extent and produced from a random code, but repetition of an identical pattern of a well-known preamble signal added to a head portion of a signal is discriminated when a bit-rate of the signal is changed. More specifically, the repetition of the identical pattern is converted into a consecutive identical signal to generate the consecutive identical signal (having a length of tens bits to thousands bits). Although the consecutive identical signal is longer than a same-code continuation length included in the signal, and is shorter than a time constant necessary to the conventional circuit by about one to three digits. Therefore, an integration time can be shortened to the same degree as the generated consecutive identical signal length, and the bit-rate can be discriminated at high speed within a preamble signal receiving time.

Abstract: In an optical component, a part of a waveguide type optical device is fixed to a convex portion of a mount. The optical component includes an optical support base, a pressure member and a pressure support base. The optical device support base is interposed between the mount and the presser member enough to be slidable in a direction parallel to surfaces of the mount and the presser member.

Abstract: In an integrated optical receiver or transmitter, both the displacement of an optical axis caused by thermal changes and the property degradation of an optical functional circuit are inhibited. A planar lightwave circuit having a substrate and a waveguide-type optical functional circuit formed thereon composed of a material different from that of the substrate, and includes a waveguide region formed only of an optical wavelength that is in contact with a side forming an emission-end face of the optical waveguide for propagating the light emitted from the optical functional circuit or an incident-end face of an optical waveguide for propagating the light incident on the optical functional circuit. The planar lightwave circuit is fixed to a fixing mount only at the bottom of the substrate where the waveguide region is formed.

Abstract: In a waveguide device, unnecessary optical power is appropriately terminated. According to an embodiment of the present invention, the waveguide device has a termination structure filled with a light blocking material to terminate light from a waveguide end. In the termination structure, a cladding and a core are removed to form a groove on an optical waveguide. The groove is filled with a material (light blocking material) that attenuates the intensity of light. Thus, light input to the termination structure is attenuated by the light blocking material, suppressing crosstalk which possibly effects on other optical devices. Thus, such a termination structure can restrain crosstalk occurred in optical devices integrated in the same substrate and can also suppress crosstalk which possibly effects on any other optical device connected directly to the substrate.