Vertical cavity surface emitting laser (VCSEL) Several common VCSELs are usually 850nm wavelength, multimode; they are characterized by low cost (production and processing, test costs), low power cons

Vertical cavity surface

emitting laser (VCSEL) Several common VCSELs are usually 850nm wavelength,

multimode; they are characterized by low cost (production and processing, test

costs), low power consumption, easy coupling (the spot is close to a circle),

and easy arraying, so CoB process can be used to achieve large-scale

integration Module. Since VCSELs have certain difficulties in achieving high

speeds, it seems that 400G should be implemented as 8x50G PAM4, which is the

form of 8 channels of 25G baud rate plus PAM4 modulation. VCSELs dominate in

applications less than 100 meters (receiving optical modules and active optical

cables) and can further integrate more on-board optical modules (OBOs).

However, VCSELs require multimode fiber and the cost is higher than that of

single-mode fiber. Datacom system manufacturers need to prepare multimode

(below 100 meters) and single-mode (greater than 100 meters) fibers.