Patent ID: 6518563
Filing Date: 2003-02-11
Classification: H01S

Abstract:
A method of determining aging of a light emitting device which is capable of selectively emitting light having different wavelengths corresponding to different channels for light transmission as a function of a tuning electrical bias supplied to the device and determining aging of an optical filter through which the light is passed, the method comprising:applying a first value of tuning electrical bias to the device which results in tuning the device to a wavelength corresponding to a desired channel while a control loop is engaged to control the temperature of the device; determining the slope of a curve which is light power from the device as a function of tuning bias, said slope determined at the first value of tuning bias while the control loop is engaged; comparing the determined slope with a prior determined value in order to detect any change from the prior value to determine aging of the device; disengaging the temperature control loop and measuring a voltage signal derived from light from the device after passing through the optical filter; and comparing the measured voltage to a prior value in order to determine aging of the filter.