Semiconductor light-emitting device

Semiconductor light-emitting device comprising:

• a light source;
• a modulator configured to have a quantum well layer for modulating output light from the light source interposed between a first conductivity-type semiconductor layer and a second conductivity-type semiconductor layer;
• and
• a mounting substrate on which the light source and the modulator are mounted, the mounting substrate having a first transmission line extending from a first connection portion electrically connected to the first conductivity-type semiconductor layer, the mounting substrate having a second transmission line extending from a second connection portion electrically connected to the second conductivity-type semiconductor layer,
• wherein
• the first transmission line and the second transmission line constitute a pair of differential signal lines, and
• the first transmission line has a width in a direction perpendicular to a transmission direction, the first connection portion having the width less than or equal to an adjoining part thereof, the first connection portion having characteristic impedance higher than the adjoining part.

Semiconductor light-emitting device comprising:

• a light source;
• a modulator for modulating output light from the light source;
• a mounting substrate on which the light source and the modulator are mounted, the mounting substrate having a first transmission line, a second transmission line, and a matching resistor;
• a first conductor for electrically connecting the modulator to the first transmission line;
• and
• a second conductor for electrically connecting the modulator to the second transmission line,
• wherein
• the first transmission line and the second transmission line constitute a pair of differential signal lines, and
• the matching resistor is connected between the first transmission line and the second transmission line, without the first conductor or the second conductor being interposed therebetween.