What is Laser Reliability Testing?
Laser reliability testing consists of a series of tests that laser diodes can be put under in order to ensure their reliability for post-production use. There are different types of tests that can be carried out and there are multiple measurements that can be taken in order to evaluate the reliability of the device. One of these tests is laser diode burn-in.
What is Laser Diode Burn In?
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 which 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.
There are two main ways to conduct burn-in tests:
BURN-IN TEST WITH SITU
At low testing volumes, or if the same system is used for burn-in and the engineering evaluation of a device it can be more cost effective to perform device parameter tests in the same system as burn-in. Yelo's burn-in systems are capable of burn-in with in-situ testing.
BURN-IN WITH SEPARATE TEST
In contrast to low production volumes, it is usually more cost effective to use constant current and temperature burn-in chambers, separate from the system used for device parameter testing. This can also allow for spectrum measurement incorporation to the testing process, as this becomes difficult to achieve when using an in-situ system.