Optical transmitting device and optical transmission system

An optical transmission system comprising:

• an optical receiving device configured to receive an optical signal;
• and
• an optical transmitting device configured to transmit the optical signal to the optical receiving device during a period notified by the optical receiving device, the optical transmitting device including:
• a laser diode to which one of a first driving current and a second driving current is provided;
• a controller configured to provide the laser diode with the first driving current to transmit the optical signal to the optical receiving device during the period notified by the optical receiving device and with a plurality of second driving currents, to emit light, different from each other in magnitude during a periodic duration different from the period notified by the optical receiving device;
• a measuring unit configured to measure an intensity of the light emitted by the laser diode;
• a calculator configured to calculate a threshold current of the laser diode, based on the intensities corresponding to the plurality of second driving currents measured by the measuring unit and magnitudes of the plurality of second driving currents;
• and
• a determination unit configured to determine a precursor of a sudden-death of the laser diode, based on an amount of variation in the threshold current calculated by the calculator during a specific period.