Preventive maintenance method for optical module and preventive maintenance apparatus for optical module

A preventive maintenance apparatus for an optical module, for preventing degradation of an optical module and performing maintenance of the optical module, the preventive maintenance apparatus being targeted for an optical module including an internal measuring instrument that measures physical quantities including optical transmission power and a bias current and an internal memory in which the measured physical quantities are recorded, the preventive maintenance apparatus comprising:

• a correlation coefficient calculator that calculates, from the optical transmission power and the bias current recorded in the internal memory of the optical module, a correlation coefficient for converting the optical transmission power to a signal quality;
• a signal quality calculator that calculates a signal quality with use of a correlation expression including the optical transmission power and the correlation coefficient;
• and
• a signal quality degradation determiner that diagnoses degradation in the signal quality by comparing the signal quality and a signal quality degradation identification value,
• the preventive maintenance apparatus being configured to report a degradation state of a light emitting element of the optical module with use of a diagnosis result obtained by the signal quality degradation determiner.