To securely simplify the complexity of an optical transmission system, which requires an optical pulse compressing device, at low cost.

The optical transmission system 100 includes an optical source 105, a dispersing element, and a passive optical compressing device 120. Deformation-limited optical pulses are generated by the optical source 105. The optical pulses are sent to the passive optical compressing device 120. The device 120 filters the pulses or performs spectrum formation normally by using a passive optical notch filter. As the frequency band of the optical pulses expands as the pulses are filtered, the temporal pulse width of the optical pulses is reduced or compressed to desirable narrow pulse width without a control signal nor high-speed electrooptic technology.