Fiber Optic PC Connectors: Single-channel vs. Multi-channel

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Over the past 30 years, fiber optic
technology has spanned its commitment constantly with, even more, endeavors
nowadays to meet the ever-increasing networking bandwidth for high-quality
Internet applications. In these applications, fiber optic connectors, serving
as mousetraps, are used to couple the source, receiver and other components to
the fiber optic cable. Fiber
optic connectors generally use either physical contact (PC) or expanded
beam technology. This article mainly discusses PC connectors from
single-channel and multi-channel aspects.

 

It’s necessary to figure out what PC
connections are first.

 

What Are PC Connection?

A PC connection is accomplished by
terminating the optical fiber into a precise ceramic ferrule. The tip of the
ceramic ferrule is polished in a precise manner to ensure that light enters and
exits at a known trajectory with little scattering or optical loss. In
achieving PC connection, there are two requirements for a cleaved fiber end
face for PC connection. One is that the fiber end face inclination is less than
0.6°, and the other is that there is no mist on the end face.

 

PC Connector Types

There are countless single-channel and
multi-channel fiber optic PC connector types available for telecommunication
and data communication industries.

 

Single-channel Connectors

 

PC connectors are characteristic of
directly mating and polishing fibers by utilizing tight tolerance ferrules and
alignment sleeves and/or mating pins. This ceramic-ferruled technology permits
reliable optical performance, with several designs becoming widely used as
industry standards. Typically, these connectors are single fiber solutions with
plastic shells. FC and ST connectors are becoming less popular but are still
used in instrumentation. LC and SC connectors are commonly used in the
telecommunication industry.

 

As a push-pull connector, LC connector,
licensed by Lucent Technologies, provides a pull-proof design and small size
perfect for high-density applications. It’s available in simplex or duplex
versions, widely used in 10Gigabit, 40Gigabit, and 100Gigabit applications.
Like Cisco QSFP-40GE-LR4 transceiver, QSFP-40GE-LR4 listed on Fiber-mart.com
establishes 40Gigabit Ethernet (GbE) links with this duplex LC connector for
10km maximum link length over single-mode fiber (SMF).

 

SC connector, developed by Nippon
Telegraph and Telephone (NTT), is recommended in the TIA/EIA-568-A Standard for
structured cabling. It’s also available in simplex or duplex versions,
typically used in Analog CATV (Cable Television) and other telecoms applications
including point to point and passive optical networking.

 

Multi-channel Connectors

 

Multi-channel connectors house multiple
fiber optic termini in a precision insertion. The termini can be configured as
a pin/socket combination or genderless. MTP/MPO connectors belong to PC
multi-channel connector.

 

The US CONEC MTP is an MPO compatible
connector that exhibits quick and reliable connections for up to 12 fibers in a
very small form factor. Just like LC connector, 40G links are likely to deploy
this kind of MPO-12 connector for high performance. Take Cisco QSFP-40G-CSR4
for example, this QSFP-40G-CSR4 transceiver sets up 40G links in 850nm
multi-mode fiber (MMF), with MPO-12 as its connector.

 

Optical Performance

Both single-channel and multi-channel
PC connectors have optical performance characterized by return loss. The return
loss of the connector is a measurement of how much light is reflected back at
the connector interface. It’s affected by alignment, contamination, and
polishing. For example, if the mating faces of the two fibers are not parallel,
some energy reflects back to the source. Additionally, contamination at the
mating interface causes reflection and scattering of light. What’s more, a poor
polish may create an end-gap separation or an end angle.

 

Featuring by the tightest tolerance
ceramic ferrules and alignment sleeves, coupled with the highest quality
termination and polishing procedures, PC connections are able to deliver
unrivaled optical performance.

 

Conclusion

Fiber optic connectors make quick fiber
connection and efficient light transmission possible, gaining more and more
popularity among their users. Fiber-mart.com offers hundreds of fiber optic
connectors, such as FC, D4, DIN, MU, the MTP/MPO ST, SC and LC, as well as their
related optic modules (eg. QSFP-40GE-LR4 and QSFP-40G-CSR4 mentioned above).
You can visit Fiber-mart.com for more information about fiber optic connectors.