From Then to Now (and Beyond): The Advancement of Multimode Optics

Multimode optics, including multimode VCSEL-based transceivers and multimode fiber, has been dominating data center short-reach links. Why? Because they can offer:

  • Lower link costs
  • Less power consumption
  • Higher resistance to fiber misalignment and dirt at connections

There are many innovations in multimode optics on the horizon that will address several challenges, helping support and refine the appeal of multimode optics in the years to come. Let’s discuss them here.

 

VCSEL: The Light Source of Multimode Optics

VCSEL stands for “vertical-cavity surface-emitting laser.” Because of its moderate cost, low power consumption and ability to be manuafactured at high volume in production facilities, it is the light source used for multimode optical transmission.

A VCSEL is typically comprised of 40 to 60 layers of alternating semiconductor materials, each λ/ 4 deep; the bottom and top mirrors of the cavity are made with distributed Bragg reflectors (DBRs).

 

Economic Advantages of Multimode Optics

When measured to singlemode optics, multimode optics continue to be the cost-effective choice for shorter-reach data center applications. The cost of multimode fiber cable is higher than that of singlemode fiber cable, but multimode transceivers are what bring the price down:

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