cisco hands-on experience

fiber optic

singlemode / multimode fiber

singlemode fiber
inglemode fiber is an optical fiber that is constructed to carry only a single ray of light. The light travels only with one wavelength trought the core and therefore singlemode prevent light rays overlapping. As a result destroying of data is not given, but can be appear at multimode fiber. With singlemode you can reach longer distances in opposite to multimode fiber. The distance of singlemode can be 50 times higher as multimode fiber. Another advantage is in some cases the higher bandwidth of singlemode fiber. Single-mode fibers are used in long-distance cables, but they require connectors with better precision and expensive devices. On this kind of fiber the light has only one way of travelling inside the fiber core. The core diameter is between 7 and 10 microns and its cladding diameter is around 125 microns, so both multi-mode and mono-mode cables have the same diameter, what makes the difference is the diameter of the core. There are three types of single-mode fibers: non dispersion-shifted fiber (NDSF), dispersion-shifted fiber (DSF) and non zero-dispersion-shifted fibers (NZ-DSF).

multimode fiber
ultimode fiber is an optical fiber that is constructed to carry multiple light rays or modes concurrently. Each at a marginally different reflection angle within the optical fiber core. Mulitmode fiber transmission is used for relatively short distances tend to disperse over longer length(modal dispersion). On multimode fibers the core diameter is greater than the core diameter of single-mode fibers, making the light to have several propagation modes, i.e. the light goes through the fiber core using several paths and not using a single path, like in single-mode fibers. Multimode fibers have a core diameter 50 to 100 microns (typical commercial values are 50, 62.5 and 100 microns) and a cladding diameter of 125 microns. Multimode fibers can be classified into graded-index and step-index, depeding on the refraction index between the core and the cladding – on graded-index there is a gradual change between the core and the cladding, while on step-index this change is abrupt. Step-index fibers can transmit data up to 50 Mbps, while grade-index fibers can transmit data up to 1 Gbps. Multi-Mode fibers are also known as MMF and they are used by short-distance fibers.
Here you can the see the composition of a fiber cable
lateral cut
step- and graded index
multimode 50µm / multimode 62.5µm / singlemode 9µm
multimode 50µm
multimode 62.5µm
singlemode 9µm
fiber categories and areas of operation
category color code fiber type attenuation in dB/km minimal modal bandwidth
OFL in MHz•km EMB2 in MHz•km
850 nm 1310 nm 1383 nm 1550 nm 850 nm 1310 nm
multimode fiber
OM1 Orange G62,5/125 3,5 1,5 n.a. n.a. 200 500 n.a.
OM2 Orange G50/125 3,5 1,5 n.a. n.a. 500 500 n.a.
OM3 Aqua G50/125 3,5 1,5 n.a. n.a. 1500 500 2000
OM4 Aqua G50/125 3,5 1,5 n.a. n.a. 3500 500 4700
monomode fiber (singlemode fiber)
OS1 Yellow E9/125 n.a. 1,0 n.a. 1,0 n.a.
OS2 Yellow E9/125 n.a. 0,4 0,4 0,4 n.a.

OFL = over-filled-launch-bandwidth
EMB = effective-modal-bandwidth

maximum transmission operating distance for several highspeed-applications with the range
Local Area Network und Storage Area Network
Ethernet OM1 OM2 OM3 OM4 OS1/OS2
100 Mbit/s 100BASE-SX 850 nm 300 m 300 m 300 m n.a.
100BASE-FX 1310 nm 2000 m 2000 m 2000 m 2000 m 2000 m
1 Gbit/s 1000BASE-SX 850 nm 300 m 500 m 1000 m 1000 m
1000BASE-LX 1310 nm 500 m 500 m 500 m 500 m 5000 m
10 Gbit/s 10GBASE-SR 850 nm 30 m 80 m 300 m 500 m
10GBASE-LR(M) 1310 nm 220 m 220 m 220 m 220 m 10.000 m
10GBASE-ER 1550 nm 40.000 m
40 Gbit/s 40GBASE-SR4 850 nm n.a. n.a. 100 m 125 m
40GBASE-LR4 1310 nm 10.000 m
40GBASE-ER4 1550 nm 40.000 m
Fibre Channel OM1 OM2 OM3 OM4 OS1/OS2
850 nm 1310 nm 1550 nm
1 Gbit/s 1GFC 300 m 500 m 800 m n.a. 10.000 m 50.000 m
2 Gbit/s 2GFC 150 m 300 m 500 m n.a. 10.000 m 50.000 m
4 Gbit/s 4GFC 70 m 150 m 380 m 400 m 10.000 m n.a.
8 Gbit/s 8GFC 20 m 50 m 150 m 190 m 10.000 m n.a.
16 Gbit/s 16GFC 15 m 35 m 100 m 125 m 10.000 m 50.000 m*
InfiniBand OM1 OM2 OM3 OM4 OS1/OS2
850 nm 1310 nm
2 Gbit/s 1X-SDR 125 m 250 m 500 m n.a. 10.000 m
4 Gbit/s 1X-DDR 65 m 125 m 200 m n.a. 10.000 m
8 Gbit/s 1X-QDR 33 m 82 m 300 m n.a. 10.000 m
8/16/24 Gbit/s 4X/8X/12X-SDR** 75 m 125 m 200 m n.a. n.a.
16/32 Gbit/s 4X/8X-DDR** 50 m 75 m 150 m n.a. n.a.

* at 1490 nm
** Increase of data transfer rate by the use of parallel data communication over 4(8) / 8(16) / 12(24) channel(fibers)

Fiber Optic Patch Cables

When you get no link, if you plugged in the fiber optic cable, do the following!!!
Check if you have inverted the fiber cable. Don’t look directly in the light coming out of the fiber optic cable. Lower wagelength cable light are more dangerous for your eyes as higher wavelenght light. To verify where the light get out, take your mobile phone – activate the camera and look into the camera. It’s the same procedure taking a picture. In that case your eyes are protected from the dangerous light rays and you see where the light come out.

  1. Lothar Beckstein Reply

    great job. thx a lot!

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      • George Reply

        thx 🙂

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    • George Reply

      Thank you very much for your feedback.

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