Optical transmission device

An optical transmission device comprising:

• a substrate on which a first optical modulator that modulates first light split off from light of a first wavelength, a second optical modulator that modulates second light split off from the light of the first wavelength, a third optical modulator that modulates third light split off from light of a second wavelength, and a fourth optical modulator that modulates fourth light split off from the light of the second wavelength are arranged in parallel along a width direction;
• a first prism that moves, to a side opposite to the third optical modulator and the fourth optical modulator along the width direction of the substrate, an optical path of first output light obtained by the first light being modulated by the first optical modulator and an optical path of second output light obtained by the second light being modulated by the second optical modulator;
• and
• a second prism that is arranged at a position away from the first prism along a longitudinal direction of the substrate and that moves, to a side opposite to the first modulator and the second optical modulator along the width direction of the substrate, an optical path of third output light obtained by the third light being modulated by the third optical modulator and an optical path of fourth output light obtained by the fourth light being modulated by the fourth optical modulator.