Patent attributes
Provided here are: a mounting section having a light-emitting element for emitting an optical signal; a mounting section arranged alongside the mounting section and having a light-emitting element for emitting an optical signal that is different in wavelength from the optical signal; and an optical multiplexer having a filter for transmitting therethrough only the wavelength of the optical signal, a mirror for reflecting the optical signal transmitted through the filter, and a filter arranged alongside the filter, for transmitting therethrough only the wavelength of the optical signal, and for reflecting the optical signal reflected by the mirror and multiplexing it with the transmitted optical signal; wherein the light-emitting element is mounted in the mounting section to be displaced toward the light-emitting element from a center in a width direction across an emission direction of the optical signal.