A fundamental measuremant for diode lasers is the light-current-voltage sweep test or in short LIV measurement. Current applied to the laser diode is swept and the intensity of the resulting emitted light is measured in the LIV test.
For example following characteristics can be determined based on the LIV measurement:
Spectral analysis is executed measuring an input of light signal magnitude vs wavelength. The results are presented on chart which has the spectrum wavelength on the horizontal axis and the amplitude displayed on the vertical axis.
For example following characteristics can be determined based on the spectral measurement:
Diode laser failure mechanisms can be divided into two main categories: infant mortality failures and wear out failures (see lifetime testing). Infant mortality failures can be caused by defects introduced during the manufacturing process of the diode lasers. These kind of defects can originate in semiconductor material during epitaxial growth for example.
Burn-in process is used to screen out infant mortality failures. In this process testing device is run for certain time (typically less than 100h) under controlled operating conditions. Typical operating parameters are tested before and after the burn-in. A notable change in parameters, when comparing before and after results, typically indicates high possibility for infant mortality failure.
Diode laser failure mechanisms can be divided into two main categories: infant mortality failures (see burn-in) and wear out failures. Wear out failures in diode lasers are typically found to be caused by the growth of non-radiative, optically absorbing defects within the active region of the diode laser.
Lifetime testing is used to identity wear out failures. This is done by collecting diode laser lifetime data under carefully controlled operating conditions. Typical operating parameters are tested during the process. Analyzing changes in the results will help to develop statistical models for predicting diode laser lifetime.
The facet visual inspection can be used to detect particles, cracks and coating defects on the diode laser facets. Automatic microscope takes an image of the front facet and the image is then analyzed either by the user or by machine vision software.