Abstract: A printed circuit board includes: a conductor plate below the inner dielectric layer; some vias through the inner dielectric layer, bonded to the conductor plate, centered at respective points on an upper surface of the conductor plate; a ground conductor above the inner dielectric layer, bonded to the vias, extending outwardly from any quadrangle with vertices being the nearest four points of the points; an electromagnetic resonance plate above the inner dielectric layer and inside the quadrangle, electrically connected to the ground conductor and the vias with a portion other than a protruding outer edge serving as a junction; an upper dielectric layer above the electromagnetic resonance plate; and a differential transmission line pair composed of a pair of strip conductors overlapping with the electromagnetic resonance plate, above the upper dielectric layer. The conductor plate and the vias constitute an electromagnetic field confinement structure.

Abstract: Provided is an optical subassembly, which is compact, is easy to manufacture, and has satisfactory high-frequency characteristics. The optical subassembly includes: an eyelet including a first surface, a second surface and a plurality of through-holes; a plurality of lead terminals; a relay substrate including a lead connection surface and a first bonding surface and having first and second conductor patterns formed across the lead connection surface and the first bonding surface; a device mounting unit including a second bonding surface having formed thereon third and fourth conductor patterns; and an optical device configured to convert one of an optical signal and the differential electrical signals into the other. The first and second conductor patterns on the first bonding surface are connected to the third and fourth conductor patterns by bonding wires, respectively, and the first and second bonding surfaces have normal directions in the same direction.

Abstract: An optical module includes: an optical semiconductor device in which a semiconductor laser and an optical modulator are integrated; a bypass capacitor including a lower electrode and an upper electrode, the bypass capacitor being connected in parallel to the semiconductor laser; a dielectric substrate having an upper surface and a lower surface, the optical semiconductor device and the bypass capacitor being surface-mounted on the upper surface, the dielectric substrate having a conductor pattern on the upper surface, the cathode electrode and the lower electrode being bonded to the conductor pattern; and a conductor block supporting the lower surface of the dielectric substrate. The lower electrode of the bypass capacitor having an overlap area overlapping with the upper surface of the dielectric substrate, the lower electrode of the bypass capacitor having an overhang area overhanging from the upper surface of the dielectric substrate.

Abstract: An optical module includes: a light source; an optical modulator capable of modulating light from the light source; a capacitor with an upper electrode and a lower electrode; and a resistor connected in series with and bonded face-to-face to the upper electrode of the capacitor. The resistor and the capacitor are connected in parallel with the optical modulator.

Abstract: The first capacitor is opposed to and electrically connected to the first back electrode. The second capacitor is opposed to and electrically connected to the second back electrode. Each of the first circuit and the second circuit has a main region that overlaps with a corresponding one of the first capacitor and the second capacitor. At least one circuit of the first circuit and the second circuit has an extension region extending from the main region toward another circuit of the first circuit and the second circuit. At least one of one of the pair of first wires and the second wire is bonded to the extension region.

Abstract: An optical module includes: an optical sub-assembly; and a flexible substrate including an insulating film, an interconnection pattern, and a spacer layer, the flexible substrate being connected to the optical sub-assembly. The insulating film has some projections, the projections protruding from a basic area in a first direction, the projections being arranged in a second direction perpendicular to the first direction, the insulating film having a flat shape with a recess between an adjacent pair of the projections. The interconnection pattern includes some pads in the basic area on a first surface of the insulating film, the pads being arranged in the second direction. The pads include some first pads adjacent to the respective projections, the pads including at least one second pad adjacent to the recess. The spacer layer is on the first surface and at each of the protrusions.

Abstract: An optical module includes: a thermoelectric cooler with an upper surface and a lower surface, the lower surface fixed to the first surface of the conductive block, the thermoelectric cooler having a Peltier device therein configured to transfer heat between the upper surface and the lower surface; a metal layer laminated on the upper surface of the thermoelectric cooler; a ground wire connecting the first surface of the conductive block and the metal layer; a photoelectric device adapted to convert an optical signal and an electrical signal at least from one to another; a mounting substrate on which the photoelectric device is mounted, the mounting substrate fixed to the upper surface of the thermoelectric cooler with at least the metal layer interposed therebetween, the mounting substrate having a first wiring pattern electrically connected to the photoelectric device.

Abstract: The relay board includes a first end face opposed to and fixed to the first surface of the conductive block, a second end face opposite to the first end face, and a top and a bottom defining thickness of the relay board. The top has a slope at a position closer to the first end face than the second end face. The slope inclines such that the thickness decreases in a direction from the first end face to the second end face. The conductor layers include a signal pattern on the top with part of the signal pattern disposed on the slope, and a first ground pattern extending from the bottom to each of the first end face and the second end face. The signal wire has one end bonded to the signal lead pin and another end bonded to the signal pattern on the slope.

Abstract: An optical module includes a photoelectric device and a flexible printed circuit board. The flexible printed circuit board includes an insulating substrate with a first surface and a second surface, a first wiring pattern on the first surface, and a second wiring pattern on the second surface. The first wiring pattern includes a signal line with a signal terminal portion at a tip and a signal-line portion narrower than the signal terminal portion, the first wiring pattern including a pair of ground pads at positions sandwiching the signal-line portion, at least part of the pair of ground pads avoiding being adjacent to the signal terminal portion. The second wiring pattern includes a ground plane overlapping with the signal-line portion and being connected to the pair of ground pads, the second wiring pattern including a signal pad connected to the signal terminal portion.

Abstract: In an optical module, optical signal output having satisfactory waveform and intensity can be obtained. A differential transmission line includes a first differential transmission line, which has a first characteristic impedance and is connected to a drive IC, a second differential transmission line, which has a second characteristic impedance and is connected to a light output element, the second characteristic impedance being smaller than the first characteristic impedance, and connecting portions configured to connect the first differential transmission line and the second differential transmission line in series with each other. A resistive element is arranged between the connecting portions. The resistive element has a resistance value that is set to a value with which an absolute value of a reflection coefficient for a signal traveling from the second differential transmission line side to the first differential transmission line side is 0.10 or less.

Abstract: An optical module includes an eyelet having a first surface, a second surface opposite to the first surface, and a penetration hole penetrating from the second surface to the first surface; a lead pin in the penetration hole, for transmitting electric signals; a pedestal protruding from the first surface in an extension direction of the lead pin; and a relay board on the pedestal, the relay board having a transmission line for electrically connecting an optical element and the lead pin. The lead pin is in no contact with an inner surface of the penetration hole. The lead pin has a flat surface which is at least a part of a surface bonded to the transmission line.

Abstract: An optical subassembly includes: a support block made of ceramic in front of the first surface, the support block having a substrate mounting surface, the support block having a first side opposite to a surface in front of the first surface; an element-mounted substrate on the substrate mounting surface, the element-mounted substrate having a first conductor pattern; a pedestal made of metal and configured to be the same potential as the eyelet, the pedestal situated in front of the first surface; and a lead pin in the through-hole and for transmitting the electric signal. The support block has a metallization pattern that is electrically connected to the pedestal and is continuous from at least a part of the substrate mounting surface to at least a part of the first side.

Abstract: An optical module includes: a first substrate with a first surface, the first substrate having some first pads on the first surface; a second substrate with a second surface, the second substrate having some second pads on the second surface, each of the first pads and a corresponding one of the second pads being opposed to each other and constituting an opposed pair of pads; a first insulation wall between an adjacent pair of the first pads, and in contact with the first surface of the first substrate; and a second insulation wall between an adjacent pair of the second pads, and in contact with the second surface of the second substrate. The first insulation wall and the second insulation wall overlap with none of the opposed pair of pads and are adjacent to each other in a direction along the first surface and the second surface.

Abstract: An insulation film has a first surface and a second surface opposite to each other and has a first portion and a second portion extending in a direction opposite to each other from a central portion. The optical subassembly is connected to the flexible printed circuit board at the central portion with the stem opposed to the second surface. The flexible printed circuit board curves with the second surface at least the central portion facing outward. The printed circuit board intervenes between edges of the first portion and the second portion and is connected to the flexible printed circuit board. The first portion and the second portion of the flexible printed circuit board curves in a shape to avoid mutual contact and three-dimensionally intersect with each other, and the first portion and the second portion on the second surface are opposed to the printed circuit board.