The FT-E408x-321 is a high radiance VCSEL designed to convert electrical current into optical power that can be used in fiber optic communications and other applications. As the current varies above threshold, the light intensity increases proportionally.
The FT-E408x-321 is designed to be used with inexpensive silicon or gallium arsenide detectors (see HFD3081-103, HFD3081-108), but excellent performance can also be achieved with some indium gallium arsenide detectors.