Fiber Optic Cables

Patch Cords

Quick Reference

APC and UPC connectors cannot and should not be mated. Not only does mating cause poor performance because the fiber cores will not touch, but it can also destroy both connectors. The last thing you want to do is cause permanent transceiver damage, especially on higher-cost single-mode equipment.

Common Fiber Types at FSU

Connector	Receptacle	Type	Mnemonic	Typical Uses
		LC-APC Single-Mode	"Little Click; not blue (thus APC)"	Patching to fiber enclosures.
		LC-UPC Single-Mode	"Little Click; blUe (thus UPC)	Terminating to network devices.
		LC Multi-Mode OM3/OM4	"Little Click"	Intra-room connections - e.g., datacenters.
		MTP/MPO-12 Multi-Mode OM4	n/a	Intra-room high-throughput connections - e.g., datacenters.

Legacy Fiber Types at FSU

Connector	Receptacle	Type	Mnemonic	Typical Uses
		LC Multi-Mode OM1/OM2	"Little Click"	Please don't use this.
		SC-APC Single-Mode	"Stick and Click; not blUe (thus APC)"	Please don't use this.
		SC-UPC Single-Mode	"Stick and Click; blUe (thus UPC)	Please don't use this.
		SC Multi-Mode OM3/OM4	"Stick and Click"	Please don't use this.
		SC Multi-Mode OM1/OM2	"Stick and Click"	Please don't use this.
		ST Multi-Mode OM1/OM2	"Stick and Twist"	Seriously, please don't use this.

Detailed Information

The buffer or jacket on patchcords is often color-coded to indicate the type of fiber used. The strain relief "boot" that protects the fiber from bending at a connector is color-coded to indicate the type of connection. Connectors with a plastic shell (such as SC connectors) typically use a color-coded shell. Standard color codings for jackets (or buffers) and boots (or connector shells) are shown below:

 Info:  Colors are not standards; they are de facto.

Cord buffer/jacket colors

Color		Meaning	1Gb	10Gb	40Gb	100Gb	400Gb
	Yellow	OS1/OS2 single-mode optical fiber, 9/125 μm	100 km	40 km	40 km	40 km
	Lime green	OM5 multi-mode optical fiber, laser-optimized, 50/125 µm	1100 m	550 m	150 m	150 m	150 m
	Aqua	OM3/OM4 multi-mode optical fiber, laser-optimized, 50/125 µm	1000 m / 1100 km	300 m / 550 m	100 m / 150 m	100 m / 150 m	150 m
	Magenta	OM3/OM4 multi-mode optical fiber, laser-optimized, 50/125 µm (12+ strands)	1000 m / 1100 km	300 m / 550 m	100 m / 150 m	100 m / 150 m	150 m
	Orange	OM1/OM2 multi-mode optical fiber, 62.5/125 μm	300 m / 600 m	30 m / 150 m	n/a	n/a	n/a
	Grey	Outdated color code for multi-mode optical fiber

Connector boot colors

Color		Meaning	Comment
	Blue	Ultra Physical Contact (UPC), 0°	With UPC connectors, insertion loss is lower than with APC. Achieving low insertion loss is typically easier with UPC connectors due to less air gaps than APC connectors. Consequently, return loss is higher with UPC because reflected light is reflected straight back toward the light source.
	Green	Angled Physical Contact (APC), 8°	The angled endface of the APC connector causes reflected light to reflect at an angle into the cladding vs. straight back toward the source. This is ideal for applications that are sensitive to return loss. Consequently, insertion loss is higher with APC than with UPC. Remember, return loss is different than insertion loss (the amount of optical power lost through a connector or cable length).
	Grey	Physical Contact (PC), 0°	Multimode fiber connectors
	Beige

APC and UPC connectors cannot and should not be mated. Not only does mating cause poor performance because the fiber cores will not touch, but it can also destroy both connectors. The last thing you want to do is cause permanent transceiver damage, especially on higher-cost single-mode equipment.

Single-Mode

A typical single-mode optical fiber has a core diameter between 8 and 10.5 µm and a cladding diameter of 125 µm. There are a number of special types of single-mode optical fiber which have been chemically or physically altered to give special properties, such as dispersion-shifted fiber and nonzero dispersion-shifted fiber. Data rates are limited by polarization mode dispersion and chromatic dispersion.

Multi-Mode

The main difference between multi-mode and single-mode optical fiber is that the former has much larger core diameter, typically 50–100 micrometers; much larger than the wavelength of the light carried in it. Because of the large core and also the possibility of large numerical aperture, multi-mode fiber has higher "light-gathering" capacity than single-mode fiber. In practical terms, the larger core size simplifies connections and also allows the use of lower-cost electronics such as light-emitting diodes (LEDs) and vertical-cavity surface-emitting lasers (VCSELs) which operate at the 850 nm and 1300 nm wavelength (single-mode fibers used in telecommunications typically operate at 1310 or 1550 nm). However, compared to single-mode fibers, the multi-mode fiber bandwidth–distance product limit is lower.

MTP/MPO

MPO (Multi-fiber Push On) cables are terminated with MPO connectors at either end. MPO fiber connectors are designed to provide multi-fiber connectivity in one connector to support high bandwidth and high-density cabling system applications. MPO connector is compliant with the IEC 61754-7 standard and the U.S. TIA-604-5 standard. At present, MPO connectors are typically available with 8, 12, 16 or 24 fibers for common data center and LAN applications, and 32, 48, 60, 72 fiber counts are also possible in large scale optical switches for specialty super high- density multi-fiber arrays.

Pinning (Male vs. Female)

MPO connectors come in two types:

Male MPO connectors

have alignment pins.

Female MPO connectors

do not have pins and require mating with a male connector.

The alignment pins ensure that the fiber cores line up correctly when two MPO connectors are connected.

Polarity

Polarity ensures that the fiber signals are transmitted correctly from the transmitter (Tx) to the receiver (Rx). There are three main types of polarity:

Polarity Type A (Straight-through)

• The fiber at position 1 on one end connects to position 1 on the other end.
• Used with Type A MPO trunks and Type A patch cables.
• Common in duplex transceivers but requires an additional A-to-A patch cable to flip polarity at one end.

Polarity Type B (Reversed)

• The fiber at position 1 on one end connects to position 12 on the other end (complete reversal).
• Used with Type B MPO trunks.
• Common in parallel optics like 40G/100G applications.

Polarity Type C (Pairwise Flip)

• Pairs of fibers are flipped (1↔2, 3↔4, etc.).
• Used in duplex fiber applications.
• Less common in modern deployments.

Choosing the Right MPO Configuration

Parallel optics (40G/100G)

Type B polarity with an MPO patch panel.

Duplex applications (10G/25G)

Type A or Type C with polarity-matching patch cords.

Modular installations

Ensure polarity consistency between MPO trunks, cassettes, and patch cords.

Differences MTP vs MPO®

In short, MTP® is just a brand of MPO cable; the Kleenex, if you will. You can use the terms "MPO" and "MTP" interchangeably. MTP® cables, short for "MulTi-fiber Pull-off", are equipped with MTP® fiber connectors at either end. MTP® connector is a trademark by US Conec for a version of the MPO connector with improved specifications. So MTP® connectors are fully compliant with all generic MPO connectors and can interconnect directly with other MPO based infrastructures. However, the MTP® connector is a multiple engineered product enhancement to improve mechanical and optical performance when compared to generic MPO connectors.

Helpful Links

http://www.fiberopticshare.com/introduction-polarity-methods-mtpmpo-systems.html

https://www.fiberopticshare.com/understanding-mtpmpo-polarity-methods-parallel-signals.html

https://www.servethehome.com/mpo-mtp-male-and-female-connector-differences/

https://www.blackbox.com/en-au/insights/black-box-explains/fibre-optic-cable/mpo-pinning-methods