Abstract: Provided here are: a sub-mount board that is provided with, on its front surface, a GND pattern, a capacitor mounting pattern and a signal line, and is provided with, on its back surface, a GND pattern; a light modulation element that is bonded to the surface of the GND pattern; a matching capacitor whose back surface is bonded to the surface of the capacitor mounting pattern and whose front surface is connected through a wire to a front surface electrode of the light modulation element; a matching resistor that makes a connection between the capacitor mounting pattern and the GND pattern; and a protective resistor that makes a connection between the signal line and the GND pattern across the sub-mount board in a board thickness direction, the signal line being connected through a wire to the front surface electrode of the light modulation element. Accordingly, the sub-mount board is small-sized.

Abstract: A first conductive pattern (13) is provided on an upper surface of the submount (7). A GND pattern (9) is provided on a lower surface of the submount (7). A lower surface electrode (21) of a capacitor (3) is bonded to the first conductive pattern (13) with solder (22). An upper surface electrode (23) of the capacitor (3) is connected to a light emitting device (2). A terminating resistor (4) is connected to the first conductive pattern (13). The first conductive pattern (13) has a protruding portion (25) which protrudes outside from the capacitor (3) in planar view. A width of the protruding portion (25) is narrower than a width of the capacitor (3).

Abstract: An optical modulator includes: laser diodes disposed in parallel with each other, each laser diode having a different lasing wavelength; optical waveguides disposed in parallel with each other with first ends facing the laser diodes; an optical isolator inserted between the laser diodes and the optical waveguides and attenuating return light reflected from the optical waveguides toward the laser diodes; a lens focusing light emitted from the laser diodes onto the optical waveguides through the optical isolator; an optical switch selecting one of the light beams exiting from the optical waveguides; and an optical modulator modulating the light beam selected by and output from the optical switch.

Abstract: An optical detecting device includes a light-detecting element for outputting an electrical signal, a pre-amplifier for amplifying the electrical signal, a signal line connected to an output of the pre-amplifier, and a resistor and a capacitor connected in series between the signal line and GND.

Abstract: An optical modulator includes: laser diodes disposed in parallel with each other, each laser diode having a different lasing wavelength; optical waveguides disposed in parallel with each other with first ends facing the laser diodes; an optical isolator inserted between the laser diodes and the optical waveguides and attenuating return light reflected from the optical waveguides toward the laser diodes; a lens focusing light emitted from the laser diodes onto the optical waveguides through the optical isolator; an optical switch selecting one of the light beams exiting from the optical waveguides; and an optical modulator modulating the light beam selected by and output from the optical switch.

Abstract: An optical detecting device includes a light-detecting element for outputting an electrical signal, a pre-amplifier for amplifying the electrical signal, a signal line connected to an output of the pre-amplifier, and a resistor and a capacitor connected in series between the signal line and GND.

Abstract: An optical module includes a stem with a piercing hole, an optical element mounted on a top surface of the stem, a lead which passes through the piercing hole, one end of the lead being connected to the optical element, and an insulating material in the piercing hole and insulating the stem from the lead. An opening of the piercing hole on the top surface of the stem is smaller than an opening of the piercing hole on an underside of the stem.

Abstract: An optical module includes a stem with a piercing hole, an optical element mounted on a top surface of the stem, a lead which passes through the piercing hole, one end of the lead being connected to the optical element, and an insulating material in the piercing hole and insulating the stem from the lead. An opening of the piercing hole on the top surface of the stem is smaller than an opening of the piercing hole on an underside of the stem.