White Paper: Test & Measurement

How to Improve Laser Diode Lifetime

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Laser diodes have increased in output power and the increased power means added waste heat. The mounting or heatsinking of the laser package is of tremendous importance because the operating temperature has a strong influence on laser lifetime and performance.

Achieving correct mounting or heatsinking of the laser package is not as simple as many would assume. Making sure the laser diode is mounted correctly will ensure the best performance and most extended lifetimes.

“Laser diode” is a generic term that includes several different semiconductor lasers and many additional types of housings or packages for these semiconductor lasers. The more common types of semiconductor lasers include Fabry-Perot laser diodes, stabilized laser diodes, vertical-cavity surface-emitting lasers (VCSELs), and quantum cascade and interband cascade lasers. Most of these laser diode types are available in many different housings or package types, depending on the laser’s output power and the options needed.

There are general precautions that must be observed for all laser diodes, including eye safety, electrostatic discharge, unpacking procedures, cleaning, electrical connections, and flammability. In addition, there are general thermal management procedures that should be in place for all laser diode types such as waste heat management, operating temperature, thermal spacers, and wavelength checks.

Open heatsinks provide no or minimal protection for the delicate laser chip. The laser chip is very fragile and must be protected from any mechanical contact or contamination. For long lifetimes, the exposed laser facets (mirror coatings) must not be contaminated with any foreign material. A number of precautions should be taken for each type of open package. Sealed packages or windowed packages are hermetically sealed at the factory prior to shipment. These offer lower risk due to the laser diode chip or laser diode bar being protected from dust, mechanical damage, humidity, outgassing, etc.

This paper discusses the various package types and the best practices for ensuring the laser diode is mounted correctly.

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