US Patent 8189636 - Electrical overstress indicator using nanocrystal coating

http://www.freepatentsonline.com/8189636.html

Finisar Corporation is a global technology leader in optical communication components and subsystems. This patent from Finisar teaches how nanocrystals can be used to visibly indicate electrical stress in lasers. Claim 1 reads:

1. A laser comprising:

an active area;

a metal contact region in electrical communication with the active area; and

a coating on the contact region configured to manifest a change in a visual attribute of the coating in response to exposure of the contact region to an electrical overstress event,

wherein the coating includes nano-crystals that are configured to change direction such that the nano-crystals are substantially oriented along a discharge path of the electrical overstress event such that this change of orientation results in a change of color.