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Four Key Benefits of Fiber Optic Transmission

Fiber optic cables are designed for long-distance, high-performance AV transmission, data networking, and telecommunications. Fiber is the transmission medium of choice for backbone providers in most of the developed world. Here we take a look at the main reasons why.

Introduction

The global fiber optics market is expected to grow to USD 7.89 billion by 2025 at a CAGR of 11.7% during the forecast period of 2018-2025, according to a report by Fior Markets. This is driven by a growing demand for Fiber to the x (FTTx) as we move increasingly towards secure, bandwidth-intensive, high-speed, high-data rate applications for both our business and personal lives.


 


The Basics: Photons versus Electrons
Unlike copper wire based transmission, in which the transmission entirely depends on electrical signals passing through the cable, fiber optic transmission involves signals in the form of light. In a fiber optic communication network that implements extenders, when data is input in the form of electrical signals, they are converted by the local transmitter unit into a light signal via a light source such as a laser. The amplitude, frequency, and phases of the light source must remain stable and free from fluctuation for the most efficient transmission. The light beam from the source travels via a fiber optic cable to the destination where the data is converted back to electrical signals by a remote receiver unit.


More details about fiber optic cables and types of transmission are covered later in this article. First, let’s look at some of the benefits of fiber cables over copper ones.

Main Benefits of Fiber Transmission

There are four main advantages that fiber optics have over copper wire based transmission:


  • Bigger Bandwidth
  • Longer Distance, Faster Speed
  • Higher Resistance
  • Greater Security


 


Bigger Bandwidth
Fiber optic cables provide significant bandwidth for signal transmission and can carry much more data than copper cables of the same diameter. The bandwidth-distance product (BDP) of transmission media is used to compare capabilities in this respect, and media with higher BDP will have longer transmission distance when sending the same bandwidth of data. The higher the BDP, the faster uncompressed video can be delivered and over greater distances, while displaying at exactly the same quality as the native signal. For example, the standard BDP for multimode fiber is 500 MHz/km, which means that 500-meter multimode fiber cable can transmit 1 GHz.


As you can see from the graphic below, which charts the transmission of the same bandwidth signal over various mediums, the BDP of single-mode fiber is much higher than multimode fiber, which is higher than twisted pair copper cable, which is higher than a standard HDMI cable.

The graphic above shows how far the same 4K HDMI signal (4K@30p with a bandwidth of 9 Gbps) can be sent over various cable types.

Longer Distance, Faster Speed
In terms of photons versus electrons, the light in fiber optic cables travels at roughly two-thirds the speed of light, while electrons in copper cables barely reach one percent of that speed. This immense speed advantage has an extreme effect on potential distances. While copper cables are mostly limited to a 100-meter standard distance, fiber optic cables can extend large bandwidth content over extremely long distances in a small diameter. Multimode fiber can triple this distance for a 4K HDMI signal, for example, and depending on the kind of cable, the wavelength, and the rest of the network, single-mode fiber can extend the same signal up to 10 km.



Higher Resistance
Unlike copper-based transmission methods, fiber optic cables contain no metallic components. As a result, they are immune to electro-magnetic interference (EMI) and radio frequency interference (RFI). Furthermore, fiber optic cables are immune to extreme changes in temperature and moisture levels, both of which can hinder transmission in copper cables.



Security
As fiber optic cables do not conduct electrical signals, it is impossible to remotely detect any data signal that is being transmitted, and attempts at physical access would be detectable by surveillance. This security makes fiber the transmission method of choice for industries such as government and banks. In terms of safety, fiber optic cables also pose no risk in spark-hazard environments such as chemical plants and oil refineries.


 


Disadvantages of Fiber
In addition to the extra costs, fiber does have some other disadvantages. Fiber optics are made of glass, and so are more delicate than copper wires and need to be handled more carefully. They are also more difficult to install, mainly due to the fact that unlike copper cables they cannot be conveniently spliced. Also, data communications are not completely in the optical domain, so repeated electrical-to-optical-to-electrical conversion is needed. And, as distances increase, more of the light carrying the data signal gets dispersed. There are two specific wavelengths (1310 nm and 1550 nm) that can combat this and provide lower attenuation, but narrow-spectrum-width lasers at these wavelengths are more difficult to manufacture, and so costs invariably increase along with distance.

Fiber Optic Transmission Technology

Fiber optic cables transmit signals using pulses of light via glass threads. For such fiber optic networks, ATEN offers a variety of optical extender solutions, including both Pro AV and KVM models.

This chart plots ATEN fiber products on a Price-Distance axis, showing light source, wavelength, and mode.

Fiber Optic Cable Structure
Fiber optic cables consist of a highly refractive central core comprised of one or more threads of glass, which is the path that the light signal travels along. Outside of the core is the cladding, which has a low refractive index, ensuring that the path of the light flows onward instead of outward. The cables lastly have a buffer coating that can vary in thickness and a colored jacket to assist in identification.


 


Multimode and single-mode fiber
The two main types of optical fiber cables are single-mode and multimode. Single-mode cables support much longer distances and higher speeds than multimode cables, because they have a smaller core and operate on a higher wavelength, and this results in a more focused light signal. A single-mode core is 8-9 microns compared to multimode’s 50 / 62.5 microns, and single mode uses 1310 nm / 1550nm while multimode uses 650-850 nm. As you can see from the diagram above, the ATEN VE882 HDMI Optical Extender can extend a 4K signal up to 300 m using multimode cables, and a 1080p signal up to 600 m using single-mode, while the CE690 USB DVI Optical KVM Extender extends AV and RS-232/USB signals up to 20 km using single-mode.

The ATEN CE690 USB DVI Optical KVM Extender extends uncompressed DVI video @ 1920 x 1200 and USB / RS-232 control signals at distances up to 20km (single-mode).

Cable Classifications
Multimode cables with 50- and 62.5-micron core diameters are classified as OM2/3/4 and OM1, respectively. OM1 and OM2 commonly use an LED light source and have an orange-colored jacket, while OM3 and OM4 usually use 850 nm VCSELs and have aqua-colored jackets. Single-mode cables are classified as OS1 and OS2, depending on differences mainly in cable construction rather optical fiber specifications. Fiber cable jacket colors also vary depending on hybrid types and whether they are meant for internal or external use.

Hybrid AOC
In addition to single-mode and multimode cables, there are hybrid cables that use a combination of both fiber and copper components. These are known as Active Optical Cables (AOC). The core fiber system utilizes VCSEL lasers and multimode fiber optics for high-speed video signal transmission, while insulated copper conductors provide the channel for control signals such as CEC. By utilizing the strengths of multimode fiber optics and copper conductors, a hybrid AOC is an ideal solution for delivering high-quality video signals over longer distances, up to 100m, compared to pure copper cable solution.


ATEN offers a True 4K HDMI 2.0 Active Optical Cable with excellent EMI-resistance capability and fully compliant with HDCP 2.2 and HDMI 2.0, including 3D, deep color, and with data rates up to 18 Gbps. For more details about ATEN’s AOC range, click here

This diagram shows an AOC cross-section.

Light Source / Laser Type
For fiber optic transmission, both LEDs and lasers can be used. For the light source, single-mode cables use high-wavelength lasers to generate light, and multimode cables use lower-wavelength lasers and LEDs, though all wavelengths are near to the infrared band that is just above the visible range. Vertical-cavity surface-emitting lasers (VCSEL) are mainly used at 850 nm for multimode communication links up to 500 m; Fabry-Pérot (FP) lasers are used when transmission distance is generally less than 20 km, the rate is generally less than 1.25G, and at the two single-mode wavelengths of 1310 nm and 1550 nm; and distributed feedback lasers (DFB) generally use the same mode and wavelengths as FP but for high-speed long-distance transmissions up to 40 km. From the diagram above, you can see that the ATEN VE883 4K HDMI Optical Extender K2 model can send a 4K HDMI signal up to 10 km over single-mode fiber cables that utilize DFB 1310 nm lasers (The VE883 K1 model interfaces with VCSEL 850 nm laser fiber cables).

The ATEN VE883 4K HDMI Optical Extender extends lossless HDMI @ 4K (plus control signals) at distances up to 300 m (multimode, OM3) and up to 10 km (single-mode) over duplex fiber optic cabling.

Duplex and BiDi Transceivers
Small form-factor pluggables (SFPs) are compact, hot-pluggable transceivers used to interface a network device motherboard (for a switch, router, media converter, or similar device) to a fiber optic or copper networking cable. The ATEN VE882 HDMI Optical Extender uses BiDi transceivers, while the VE883 4K HDMI Optical Extender uses Duplex SFP++.

ATEN Fiber Solutions

For quick reference, please see the table below.

 

 VE882

 VE883 K1

 VE883 K2

 CE680

 CE690

Fiber Type 

 SM

 OM3

 OM3

 OM4

 SM

 OM3 / SM

 SM

Extender Type

 AV

 KVM

Video Support

 HDMI

 DVI

Extension Range

 600 m

 300 m

 300 m

 400 m

 10 km

300 m (OM3)

600 m (SM) 

20 km (SM)

Data Rate 

 3.125 Gbps

 10 Gbps

 3.125 Gbps

Highest Resolution 

 1080p@60Hz

4K@60Hz (4:2:0)

4K@30Hz (4:4:4) 

 1920x1200@60Hz

Peripheral Signal Extension 

 IR, UART

 IR, UART, USB 2.0, Gigabit Ethernet

 RS-232, USB

 

For more detailed information about ATEN fiber products:  

Pro AV optical extenders https://www.aten.com/au/en/products/professional-audiovideo/video-extenders/?f3965[]=5

All fiber products https://www.aten.com/au/en/search/?q=fiber