Burn-in tests are applied to laser diodes during their manufacturing process to identify potentially defective devices. this early detection allows for a large decrease in infant mortality rates of the devices reaching post-production. In other words, they can be used to screen out lasers with short life expectancies.

All laser diodes are subjected to burn-in testing during manufacturing. Its aim is to identify and remove any defective devices at an early stage that would later suffer from infant mortality. Screening out laser diodes with short life expectancies involves burn-in testing the devices at high temperatures. This will lead to an improved level of reliability among the remaining lasers. Burn-in testing can greatly increase test cycle times and manufacturing costs. It is therefore common that laser diodes have burn-in tests that run for under 100 hours. A laser diode is screened out through burn-in tests if a change in one or more of the operating parameters is detected. These key operating parameters are measured both before and after the high-temperature burn-in tests. It is important during testing that the temperature and operating current are as high as possible to minimise the time required for test completion. However, it is also important to avoid setting them too high that the laser degrades in a manner that would not be present during normal operating conditions.