10, 40 & 100 Gig
With each passing year demand for higher data rates in data center environments grow. More and more sophisticated equipment is introduced into the marketplace and more users need access to data center services. Today, we are able to transmit data within the data center at 10 Gig / second using multimode fiber.
OM2, OM3, and OM4 are all terms used to describe different grades of 50/125 multimode fibers by the ISO/TEC 11801 and standard.
Each grade has its own specifications in regards to its data transmission properties:
|
OM2 |
OM3 |
OM4 |
Physical Characteristics |
50/125 Optical Fiber Optimized for Use with LED Transmitters |
50/125 Optical Fiber Optimized for Use with Laser Transmitters |
50/125 Optical Fiber Optimized for Use with Laser Transmitters |
Jacket Color Code |
Orange |
Aqua |
Aqua |
Transmission Properties |
|
|
|
Overfilled Launch |
500/500 |
1500/500 |
3500/500 |
Laser Launch |
Not Specified |
2000 |
4700 |
1 Gb/s Distance |
550 Meters |
Not Specified |
Not Specified |
10 Gb/s Distance |
82 Meters |
300 Meters |
500 Meters |
While this seems like an enormous transmission rate, user demand will catch up with it fairly quickly. Thankfully technologies are emerging that will allow transfer rates of up to 100 Gig / second in the data center. Also on the horizon are 10 Gig / second data rates to the desktop. As demand for service grows so must the transmission standard. These new increased data rates will require cleaner signals for transmission of laser pulses on multimode fiber.
Introduction of Laser Optimized Fiber
Standard, Non-Laser Optimized Multimode fiber, typically is manufactured with an optical defect in the center of the core. While this defect is not detrimental to the transmission of light emitted by LED's, coherent light emitted by lasers is greatly affected. In order to efficiently transmit laser light through multimode cable one must use a mode conditioning cable. These costly patch cables offset the launch of the laser to avoid the center defect. In the early 2000's optical fiber manufactures began producing fiber without the center defect… Laser Optimized Multimode Fiber was born. OM3 was the first standard to emerge, codifying laser optimization of multimode fiber. This technology was the first to allow designs of laser transmission systems utilizing multimode optical fiber without the use of mode conditioning cables. This new fiber when paired with new low cost Vertical-cavity surface-emitting laser technology allowed for 10 Gig transmission.
The next direction to boosting performance of optical networks in the datacenter lies in parallel optics. Parallel optics utilizes VCSEL lasers to launch a signal down multiple paths of a multifiber connector and incorporates an MPO/MTP® brand interface for the transceivers. In 40G applications, a 12 fiber ferruled MTP brand interface utilizing 8 of the fibers would be used (4 for transmit, 4 for receive, while the 4 in the middle would remain unused). In 100G applications, a MTP brand 24 fiber ferrule is utilized in a similar manner.
Polarity is maintained via a Roll Over configuration where:
Fiber 1 Corresponds to Position 1 on Side A, Position 12 on Side B
Fiber 2 Corresponds to Position 2 on Side A, Position 11 on Side B
…
Fiber 12 Corresponds to Position 12 on Side A, Position 1 on Side B
40 G transceivers currently have the name QSFP (Quad Small Form Factor Pluggable) and are currently available on the open market from several manufacturers.