Optical fibers

Optical fiber

An optical fiber (or optical fibre) is a flexible, transparent fiber made by drawingglass (silica) or plastic to a diameter slightly thicker than that of a human hair.Optical fibers are used most often as a means to transmit light between the two ends of the fiber and find wide usage in fiber-optic communications, where they permit transmission over longer distances and at higher bandwidths (data rates) than wire cables. Fibers are used instead of metal wires because signals travel along them with lesser amounts of loss; in addition, fibers are also immune toelectromagnetic interference, a problem which metal wires suffer from excessively. Fibers are also used for illumination, and are wrapped in bundles so that they may be used to carry images, thus allowing viewing in confined spaces, as in the case of a fiberscope. Specially designed fibers are also used for a variety of other applications, some of them being fiber optic sensors and fiber lasers.

Optical fibers typically include a transparent core surrounded by a transparentcladding material with a lower index of refraction. Light is kept in the core by the phenomenon of total internal reflection which causes the fiber to act as awaveguide. Fibers that support many propagation paths or transverse modes are called multi-mode fibers (MMF), while those that support a single mode are calledsingle-mode fibers (SMF). Multi-mode fibers generally have a wider core diameter and are used for short-distance communication links and for applications where high power must be transmitted. Single-mode fibers are used for most communication links longer than 1,000 meters (3,300 ft).

An important aspect of a fiber optic communication is that of extension of the fiber optic cables such that the losses brought about by joining two different cables is kept to a minimum. Joining lengths of optical fiber often proves to be more complex than joining electrical wire or cable and involves the carefully cleaving of the fibers, perfect alignment of the fiber cores and the splicing of these aligned fiber cores. For applications that demand a permanent connection a mechanical splicewhich holds the ends of the fibers together mechanically could be used or a fusion splice that uses heat to fuse the ends of the fibers together could be used. Temporary or semi-permanent connections are made by means of specializedoptical fiber connectors.

The field of applied science and engineering concerned with the design and application of optical fibers is known as fiber optics.

History

Daniel Colladon first described this “light fountain” or “light pipe” in an 1842 article titled On the reflections of a ray of light inside a parabolic liquid stream. This particular illustration comes from a later article by Colladon, in 1884.

Guiding of light by refraction, the principle that makes fiber optics possible, was first demonstrated by Daniel Colladon and Jacques Babinet in Paris in the early 1840s.John Tyndall included a demonstration of it in his public lectures in London, 12 years later. Tyndall also wrote about the property of total internal reflection in an introductory book about the nature of light in 1870:

When the light passes from air into water, the refracted ray is bent towardsthe perpendicular... When the ray passes from water to air it is bent from the perpendicular... If the angle which the ray in water encloses with the perpendicular to the surface be greater than 48 degrees, the ray will not quit the water at all: it will be totally reflected at the surface.... The angle which marks the limit where total reflection begins is called the limiting angle of the medium. For water this angle is 48°27′, for flint glass it is 38°41′, while for diamond it is 23°42′.

Unpigmented human hairs have also been shown to act as an optical fiber.

Practical applications, such as close internal illumination during dentistry, appeared early in the twentieth century. Image transmission through tubes was demonstrated independently by the radio experimenter Clarence Hansell and the television pioneer John Logie Baird in the 1920s. The principle was first used for internal medical examinations by Heinrich Lamm in the following decade. Modern optical fibers, where the glass fiber is coated with a transparent cladding to offer a more suitable refractive index, appeared later in the decade. Development then focused on fiber bundles for image transmission. Harold Hopkins and Narinder Singh Kapany at Imperial College in London achieved low-loss light transmission through a 75 cm long bundle which combined several thousand fibers. Their article titled "A flexible fibrescope, using static scanning" was published in the journal Nature in 1954. The first fiber optic semi-flexible gastroscope was patented by Basil Hirschowitz, C. Wilbur Peters, and Lawrence E. Curtiss, researchers at theUniversity of Michigan, in 1956. In the process of developing the gastroscope, Curtiss produced the first glass-clad fibers; previous optical fibers had relied on air or impractical oils and waxes as the low-index cladding material.

A variety of other image transmission applications soon followed.

In 1880 Alexander Graham Bell and Sumner Tainter invented the Photophone at the Volta Laboratory in Washington, D.C., to transmit voice signals over an optical beam. It was an advanced form of telecommunications, but subject to atmospheric interferences and impractical until the secure transport of light that would be offered by fiber-optical systems. In the late 19th and early 20th centuries, light was guided through bent glass rods to illuminate body cavities. Jun-ichi Nishizawa, a Japanese scientist at Tohoku University, also proposed the use of optical fibers for communications in 1963, as stated in his book published in 2004 in India. Nishizawa invented other technologies that contributed to the development of optical fiber communications, such as the graded-index optical fiber as a channel for transmitting light from semiconductor lasers. The first working fiber-optical data transmission system was demonstrated by German physicistManfred Börner at Telefunken Research Labs in Ulm in 1965, which was followed by the first patent application for this technology in 1966. Charles K. Kao and George A. Hockham of the British company Standard Telephones and Cables(STC) were the first to promote the idea that the attenuation in optical fibers could be reduced below 20 decibels per kilometer (dB/km), making fibers a practical communication medium. They proposed that the attenuation in fibers available at the time was caused by impurities that could be removed, rather than by fundamental physical effects such as scattering. They correctly and systematically theorized the light-loss properties for optical fiber, and pointed out the right material to use for such fibers — silica glass with high purity. This discovery earned Kao the Nobel Prize in Physics in 2009.

NASA used fiber optics in the television cameras that were sent to the moon. At the time, the use in the cameras was classified confidential, and only those with sufficient security clearance or those accompanied by someone with the right security clearance were permitted to handle the cameras.

The crucial attenuation limit of 20 dB/km was first achieved in 1970, by researchers Robert D. Maurer, Donald Keck, Peter C. Schultz, and Frank Zimar working for American glass maker Corning Glass Works, now Corning Incorporated. They demonstrated a fiber with 17 dB/km attenuation by doping silica glass with titanium. A few years later they produced a fiber with only 4 dB/km attenuation using germanium dioxide as the core dopant. Such low attenuation ushered in the era of optical fiber telecommunication. In 1981, General Electric produced fused quartz ingots that could be drawn into strands 25 miles (40 km) long.

Attenuation in modern optical cables is far less than in electrical copper cables, leading to long-haul fiber connections with repeater distances of 70–150 kilometers (43–93 mi). The erbium-doped fiber amplifier, which reduced the cost of long-distance fiber systems by reducing or eliminating optical-electrical-optical repeaters, was co-developed by teams led byDavid N. Payne of the University of Southampton and Emmanuel Desurvire at Bell Labs in 1986. Robust modern optical fiber uses glass for both core and sheath, and is therefore less prone to aging. It was invented by Gerhard Bernsee ofSchott Glass in Germany in 1973.

The emerging field of photonic crystals led to the development in 1991 of photonic-crystal fiber,which guides light bydiffraction from a periodic structure, rather than by total internal reflection. The first photonic crystal fibers became commercially available in 2000. Photonic crystal fibers can carry higher power than conventional fibers and their wavelength-dependent properties can be manipulated to improve performance.

Uses

Communication

Main article: Fiber-optic communication

Optical fiber can be used as a medium for telecommunication and computer networking because it is flexible and can be bundled as cables. It is especially advantageous for long-distance communications, because light propagates through the fiber with little attenuation compared to electrical cables. This allows long distances to be spanned with few repeaters.

The per-channel light signals propagating in the fiber have been modulated at rates as high as 111 gigabits per second(Gbit/s) by NTT, although 10 or 40 Gbit/s is typical in deployed systems. In June 2013, researchers demonstrated transmission of 400 Gbit/s over a single channel using 4-mode orbital angular momentum multiplexing.

Each fiber can carry many independent channels, each using a different wavelength of light (wavelength-division multiplexing (WDM)). The net data rate (data rate without overhead bytes) per fiber is the per-channel data rate reduced by the FEC overhead, multiplied by the number of channels (usually up to eighty in commercial dense WDM systems as of 2008). As of 2011 the record for bandwidth on a single core was 101 Tbit/s (370 channels at 273 Gbit/s each). The record for a multi-core fiber as of January 2013 was 1.05 petabits per second. In 2009, Bell Labs broke the 100 (petabit per second)×kilometer barrier (15.5 Tbit/s over a single 7,000 km fiber).

For short distance application, such as a network in an office building, fiber-optic cabling can save space in cable ducts. This is because a single fiber can carry much more data than electrical cables such as standard category 5 Ethernet cabling, which typically runs at 100 Mbit/s or 1 Gbit/s speeds. Fiber is also immune to electrical interference; there is no cross-talk between signals in different cables, and no pickup of environmental noise. Non-armored fiber cables do not conduct electricity, which makes fiber a good solution for protecting communications equipment in high voltageenvironments, such as power generation facilities, or metal communication structures prone to lightning strikes. They can also be used in environments where explosive fumes are present, without danger of ignition. Wiretapping (in this case, fiber tapping) is more difficult compared to electrical connections, and there are concentric dual-core fibers that are said to be tap-proof.

Fibers are often also used for short-distance connections between devices. For example, most high-definition televisionsoffer a digital audio optical connection. This allows the streaming of audio over light, using the TOSLINK protocol.

Advantages over copper wiring

The advantages of optical fiber communication with respect to copper wire systems are:

Broad bandwidth

A single optical fiber can carry 3,000,000 full-duplex voice calls or 90,000 TV channels.

Immunity to electromagnetic interference

Light transmission through optical fibers is unaffected by other electromagnetic radiation nearby. The optical fiber is electrically non-conductive, so it does not act as an antenna to pick up electromagnetic signals. Information traveling inside the optical fiber is immune to electromagnetic interference, even electromagnetic pulses generated by nuclear devices.

Low attenuation loss over long distances

Attenuation loss can be as low as 0.2 dB/km in optical fiber cables, allowing transmission over long distances without the need for repeaters.

Electrical insulator

Optical fibers do not conduct electricity, preventing problems with ground loops and conduction of lightning. Optical fibers can be strung on poles alongside high voltage power cables.

Material cost and theft prevention

Conventional cable systems use large amounts of copper. In some places, this copper is a target for theft due to its value on the scrap market.

Sensors

Main article: Fiber optic sensor

Fibers have many uses in remote sensing. In some applications, the sensor is itself an optical fiber. In other cases, fiber is used to connect a non-fiberoptic sensor to a measurement system. Depending on the application, fiber may be used because of its small size, or the fact that no electrical power is needed at the remote location, or because many sensors can be multiplexed along the length of a fiber by using different wavelengths of light for each sensor, or by sensing the time delay as light passes along the fiber through each sensor. Time delay can be determined using a device such as an optical time-domain reflectometer.

Optical fibers can be used as sensors to measure strain, temperature, pressure and other quantities by modifying a fiber so that the property to measure modulates the intensity, phase, polarization, wavelength, or transit time of light in the fiber. Sensors that vary the intensity of light are the simplest, since only a simple source and detector are required. A particularly useful feature of such fiber optic sensors is that they can, if required, provide distributed sensing over distances of up to one meter. In contrast, highly localized measurements can be provided by integrating miniaturized sensing elements with the tip of the fiber. These can be implemented by various micro- and nanofabrication technologies, such that they do not exceed the microscopic boundary of the fiber tip, allowing such applications as insertion into blood vessels via hypodermic needle.

Extrinsic fiber optic sensors use an optical fiber cable, normally a multi-mode one, to transmit modulated light from either a non-fiber optical sensor—or an electronic sensor connected to an optical transmitter. A major benefit of extrinsic sensors is their ability to reach otherwise inaccessible places. An example is the measurement of temperature inside aircraft jet engines by using a fiber to transmit radiation into a radiation pyrometer outside the engine. Extrinsic sensors can be used in the same way to measure the internal temperature of electrical transformers, where the extreme electromagnetic fieldspresent make other measurement techniques impossible. Extrinsic sensors measure vibration, rotation, displacement, velocity, acceleration, torque, and twisting. A solid state version of the gyroscope, using the interference of light, has been developed. The fiber optic gyroscope (FOG) has no moving parts, and exploits the Sagnac effect to detect mechanical rotation.

Common uses for fiber optic sensors includes advanced intrusion detection security systems. The light is transmitted along a fiber optic sensor cable placed on a fence, pipeline, or communication cabling, and the returned signal is monitored and analyzed for disturbances. This return signal is digitally processed to detect disturbances and trip an alarm if an intrusion has occurred.

Power transmission

Optical fiber can be used to transmit power using a photovoltaic cell to convert the light into electricity. While this method of power transmission is not as efficient as conventional ones, it is especially useful in situations where it is desirable not to have a metallic conductor as in the case of use near MRI machines, which produce strong magnetic fields. Other examples are for powering electronics in high-powered antenna elements and measurement devices used in high-voltage transmission equipment.

Introduction to Ring Topologie

Ring network

A ring network is a network topology in which each node connects to exactly two other nodes, forming a single continuous pathway for signals through each node - a ring. Data travel from node to node, with each node along the way handling every packet.

Rings can be unidirectional, with all traffic travelling either clockwise or anticlockwise around the ring, or bidirectional (as in SONET/SDH). Because a unidirectional ring topology provides only one pathway between any two nodes, unidirectional ring networks may be disrupted by the failure of a single link. A node failure or cable break might isolate every node attached to the ring. In response, some ring networks add a "counter-rotating ring" (C-Ring) to form a redundant topology: in the event of a break, data are wrapped back onto the complementary ring before reaching the end of the cable, maintaining a path to every node along the resulting C-Ring. Such "dual ring" networks include Spatial Reuse Protocol, Fiber Distributed Data Interface (FDDI), and Resilient Packet Ring. 802.5 networks - also known as IBM token ring networks - avoid the weakness of a ring topology altogether: they actually use a star topology at the physical layer and a media access unit (MAU) to imitate a ring at the datalink layer.

Some SONET/SDH rings have two sets of bidirectional links between nodes. This allows maintenance or failures at multiple points of the ring usually without loss of the primary traffic on the outer ring by switching the traffic onto the inner ring past the failure points.

Advantages

See also: Ring Protection

• Very orderly network where every device has access to the token and the opportunity to transmit
• Performs better than a bus topology under heavy network load
• Does not require a central node to manage the connectivity between the computers
• Due to the point to point line configuration of devices with a device on either side (each device is connected to its immediate neighbor), it is quite easy to install and reconfigure since adding or removing a device requires moving just two connections.
• Point to point line configuration makes it easy to identify and isolate faults.
• reconfiguration for line faults of bidirectional rings can be very fast, as switching happens at a high level, and thus the traffic does not require individual rerouting

Disadvantages

• One malfunctioning workstation can create problems for the entire network. This can be solved by using a dual ring or a switch that closes off the break.
• Moving, adding and changing the devices can affect the network
• Communication delay is directly proportional to number of nodes in the network
• Bandwidth is shared on all links between devices
• More difficult to configure than a Star: node adjunction = Ring shutdown and reconfiguration

Misconceptions

• "Token Ring is an example of a ring topology." 802.5 (Token Ring) networks do not use a ring topology at layer 1. As explained above, IBM Token Ring (802.5) networks imitate a ring at layer 2 but use a physical star at layer 1.
• "Rings prevent collisions." The term "ring" only refers to the layout of the cables. It is true that there are no collisions on an IBM Token Ring, but this is because of the layer 2 Media Access Control method, not the physical topology (which again is a star, not a ring.) Token passing, not rings, prevent collisions.
• "Token passing happens on rings." Token passing is a way of managing access to the cable, implemented at the MAC sublayer of layer 2. Ring topology is the cable layout at layer one. It is possible to do token passing on a bus (802.4) a star (802.5) or a ring (FDDI). Token passing is not restricted to rings.

Windows Store apps

Windows Store apps

Alongside Office RT, free versions of OneNote and the Lync client were made available as Windows Store apps upon the release of Windows 8 and RT. The OneNote app, originally known as OneNote MX, contains a limited feature set in comparison to its desktop version, but is also optimized for use on tablets. The OneNote app has since received several major updates, including camera integration, printing abilities, and multiple inking options.

Universal Microsoft Word, Excel, and PowerPoint apps for Windows 10 are in the preview stage and are set for release later in 2015.

Office Mobile

Further information: Microsoft Office Mobile

Windows Phone 8 ships with an updated version of the Office Mobile suite, consisting of mobile versions of Word, Excel, PowerPoint, and OneNote. In comparison to their Windows Phone 7 versions, the new versions add an improved Office Hub interface that can sync recently opened and modified documents (including changes to documents stored via Office 365 and SkyDrive), a separated OneNote app with additional features (such as voice notes and integration with the new "Rooms" functionality of the OS), and improved document editing and viewing functionality.

In June 2013, Microsoft released a version of Office Mobile for iPhone; it is similar to the Windows Phone version, but originally requires an Office 365 subscription to use. A version for Android smartphones was released in July 2013; it, too, originally needed Office 365 for use.

Apps for iPad and Android tablet computers were released in March 2014 and January 2015, respectively These, along with their smartphone equivalents, have been made free for personal use, though certain premium features have been paywalled and require Office 365, which includes licensing of the apps for business use.

Windows 10 Mobile, set for release later in 2015, will come with brand new Office apps, more in line with their iPhone and Android equivalent, and making use of the "universal app" platform pioneered with Windows 10.

Comparison

Comparison of Office 2013 suites

	As an individual product	Traditional editions						Office 365 subscriptions[46][67]
		Office RT	Home & Student	Home & Business	Standard	Professional	Professional Plus	Personal[68]	Home	University[69]	Small Business Premium	ProPlus	Enterprise
Availability	Varies	Windows RT	Retail,OEM	Retail,OEM	Volume licensing	Retail, OEM	Volume licensing	Software plus services	Software plus services	Software plus services	Software plus services	Software plus services	Software plus services
Maximum users	1	1	1	1	As licensed	1	As licensed	1	all users in one household[70]	1	10	25[71]	Unlimited
Devices per user	1	1	1	1	As licensed	1	As licensed	1 computer and 1 mobile	5 shared among all users[70]	2 computers and 2 mobiles	5	5[71]	5
Commercial use allowed?	Yes	Separate2	No	Yes	Yes	Yes	Yes	No	No[72]	No	Yes	Yes	Yes
Word	Yes	Yes1	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Excel	Yes	Yes1	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
PowerPoint	Yes	Yes1	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
OneNote	Yes3	Yes1	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Outlook	Yes	Yes1	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Publisher	Yes	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Access	Yes	No	No	No	No	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
InfoPath	No	No	No	No	No	No	Yes	No	No	No	No4	Yes	Yes
Lync	Yes3	No	No	No	No	No	Yes	No	No	No	Yes	Yes	Yes
SharePoint Designer	Yes	No	No	No	No	No	No	No	No	No	No	No	No
Project Has multiple editions	Yes	No	No	No	No	No	No	No	No	No	No	No	No
Visio Has multiple editions	Yes	No	Viewer	Viewer	Viewer	Viewer	Viewer	Viewer	Viewer	Viewer	Viewer	Viewer	Viewer

Remarks

¹ The Windows RT versions do not include all of the functionality provided by other versions of Office.

² Commercial use of Office RT is allowed through volume licensing or business subscriptions to Office 365.

³ Windows Store versions are also available.

⁴ InfoPath was initially part of Office 365 Small Business Premium. However, it no longer is.

System requirements

Each Microsoft Office 2013 application has the following requirements, although there may be app-specific requirements.

Item	Requirement
CPU	1 GHz clock speed, IA-32 or x64 architecture with SSE2 support
RAM	IA-32 edition: 1 GB x64 edition: 2 GB
Hard disk drive	3.0 GB free disk space
Operating system	Windows 7 Windows Server 2008 R2 Windows 8 Windows Server 2012 Windows 8.1 Windows Server 2012 R2
Software	.NET Framework 3.5, 4.0 or 4.5

In addition to these, graphics hardware acceleration requires a screen resolution of 1024×576 pixels or larger and a DirectX 10-compliant GPU with at least 64 MB of video memory (in case of absence of the required hardware, however, Office 2013 applications can still run without graphics acceleration.)

Microsoft Office 2013

Microsoft Office 2013 (formerly Office 15) is a version of Microsoft Office, a productivity suite for Microsoft Windows. It is the successor ofMicrosoft Office 2010 and includes extended file format support, user interface updates and support for touch among its new features.Office 2013 is suitable for IA-32 and x64 systems and requires Windows 7, Windows Server 2008 R2 or a later version of either. A version of Office 2013 comes included on Windows RT devices.

Development on this version of Microsoft Office was started in 2010 and ended on October 11, 2012, when Microsoft Office 2013 was released to manufacturing. Microsoft released Office 2013 to general availability on January 29, 2013.^[1] This version includes new features such as integration support for online services (including SkyDrive,Outlook.com, Skype, Yammer and Flickr), improved format support forOffice Open XML (OOXML), OpenDocument (ODF) and Portable Document Format (PDF) and support for multi-touch interfaces.

Microsoft Office 2013 comes in twelve different editions, including three editions for retail outlets, two editions for volume licensing channel, five subscription-based editions available through Microsoft Office 365program, the web application edition known as Office Web Apps and the Office RT edition made for tablets and mobile devices. Office Web Apps are available free of charge on the web although enterprises may obtain on-premises installations for a price. Microsoft Office applications may be obtained individually; this includes Microsoft Visio, Microsoft Project and Microsoft SharePoint Designer which are not included in any of the twelve editions.

On February 25, 2014, Microsoft Office 2013 Service Pack 1 (SP1) was released.

Development

Development started in 2010 while Microsoft was finishing work on Office 14, released as Microsoft Office 2010. On January 30, 2012, Microsoft released a technical preview of Office 15, build 3612.1010, to a selected group of testers bound by non-disclosure agreements.

On July 16, 2012, Microsoft held a press conference to show off Office 2013 and to release the Consumer Preview. The Office 2013 Consumer Preview is a free, fully functional version but will expire 60 days after the final product's release.An update was issued for the Office 2013 Customer Preview suite on October 5.

Office 2013 was released to manufacturing on October 11, 2012. It was made available to TechNet and MSDNsubscribers on October 24. On November 15, 2012, 60-days trial versions of Microsoft Office 2013 Professional Plus,Project Professional 2013 and Visio Professional 2013 were made available to the public over the Internet. Microsoft has released Office 2013 for general availability on January 29, 2013. Microsoft released the service pack 1 update on February 25, 2014.

Features

New features

Office 2013 is more cloud-based than previous versions; a domain login, Office 365 account, or Microsoft account can now be used to sync Office application settings (including recent documents) between devices, and users can also save documents directly to their SkyDrive account.

Microsoft Office 2013 includes updated support for ISO/IEC 29500, the International Standard version of Office Open XML(OOXML) file format: in particular it supports saving in the "Strict" profile of ISO/IEC 29500 (Office Open XML Strict). It also supports OASIS version 1.2 of ISO/IEC 26300:2006, Open Document Format, which Office 2013 can read and write. Additionally, Office 2013 provides full read, write, and edit support for ISO 32000 (PDF).

New features include a new read mode in Microsoft Word, a presentation mode in Microsoft PowerPoint and improvedtouch and inking in all of the Office programs. Microsoft Word can also insert video and audio from online sources as well as the capability to broadcast documents on the Web. Word and PowerPoint also have bookmark-like features which sync the position of the document between different computers.

The Office Web Apps suite was also updated for Office 2013, introducing additional editing features and interface changes.

Other features of Office 2013 include:

• Flatter look of the Ribbon interface and subtle animations when typing or selecting (Word and Excel)
• A new visualization for scheduled tasks in Microsoft Outlook
• Remodeled start screen
• New graphical options in Word
• Objects such as images can be freely moved; they snap to boundaries such as paragraph edges, document margin and or column boundaries
• Online picture support with content from Office.com, Bing.com and Flickr (by default, only images in public domain)
• Ability to return to the last viewed or edited location in Word and PowerPoint
• New slide designs, animations and transitions in PowerPoint 2013
• Support for Outlook.com and Hotmail.com in Outlook
• Support for integration with Skype, Yammer and SkyDrive
• IMAP special folders support
• Excel 2013 supports new limit models, as follows:

Quantifiable limits in objects

Object	Upper limit
Characters in a table or column name	100 characters
Number of tables in a model	2,147,483,647 bytes (2 GiB minus 1 byte)
Number of columns and calculated columns in a table	2,147,483,647 bytes (2 GiB minus 1 byte)
Memory limit, checked when saving a workbook	4,294,967,296 bytes (4 GiB)
Concurrent requests per workbook	6
Number of connections	5
Number of distinct values in a column	1,999,999,997
Number of rows in a table	1,999,999,997
String length	536,870,912 bytes (512 MiB)

Restrictions in objects

Category	Details
Reserved characters that cannot be used in a Name1	. , ; ' ` : / \ * | ? " & % $ ! + = () [] {} < >

Remarks

¹ "Name", in this context, is a form of variable in Microsoft Excel

Removed features

The following features are removed from Microsoft Office 2013.

Removed from the entire suite

• Microsoft SharePoint Workspace
• Microsoft Clip Organizer
• Microsoft Office Picture Manager
• Office 2007 and Office 2010 chart styles
• Ability to insert a 3D cone, pyramid, or cylinder chart (It is still possible to insert a 3D rectangle chart and change the shape after insertion.)
• Only basic version of help files available while offline. There is no longer an option to install local help files during installation.

Features removed from Microsoft Word

• Custom XML markup has been removed for legal reasons
• Older WordArt objects are now converted to new WordArt objects
• Word 2013 no longer uses ClearType

Features removed from Microsoft Access

• Access Data Projects (ADP)
• Support for Jet 3.x IISAM
• Access OWC control
• dBASE support suite

Features removed from Microsoft Outlook

• Download Headers Only mode for IMAP
• Outlook Exchange Classic offline
• Microsoft Exchange Server 2003 support
• Public Folder Free/Busy feature (/Cleanfreebusy startup switch)
• Ability to import from or export to any formats other than Personal Storage Table (PST) or comma-separated values(CSV)
• Notes and Journal customization
• Outlook Activities tab
• Outlook Mobile Service (OMS)
• Outlook Search through Windows Shell

Features removed from Microsoft PowerPoint

• Support for Visio Drawing

Changes

Distribution changes

Unlike past versions of Office, retail copies of Office 2013 on DVD are only offered in select regions, such as those Microsoft classifies as emerging markets, as well as Australia, at the discretion of retailers. In all other regions, retail copies of Office 2013 and Office 365 subscriptions only contain a product key, and direct users to the Office website to redeem their license and download the software.

Licensing changes

The original license agreement for retail editions of Microsoft Office 2013 was different from the license agreements of retail editions of previous versions of Microsoft Office in two significant ways. The first of these was that the software could no longer be transferred to another computer. In previous versions of Office, this restriction applied only to OEM editions; retail Office license agreements allowed uninstalling from one computer to install on another computer.

Digitally downloaded copies of Office were also said to be permanently locked to that PC's hardware, preventing it from being transferred to any other computing device. Should the buyer have wished to use Office 2013 on a different computer, or if they later became unable to use the computing device that the original license was downloaded to (e.g. hardware became inoperable due to malfunction) then a completely new, full-priced copy of Office 2013 would have to have been purchased to replace the prior one. Microsoft stated that this change was related to the software piracy that has been rampant for years, worldwide. However, many commentators saw this change as an effort to forcibly move its customers towards the subscription-based business model used by the Office 365 service. The legality of this move, particularly in Europe, has been questioned.

However, on March 6, 2013, Microsoft announced that equivalent transfer rights to those in the Office 2010 retail license agreements are applicable to retail Office 2013 copies effective immediately. Transfer of license from one computer to another owned by the same user is now allowed every 90 days, except in the case of hardware failure, in which the license may be moved sooner. The first user of the product is now also allowed to transfer it to another user. The second difference, which remains in the updated licensing agreement, is that the software can be installed on only one computer. In previous versions of Office, this restriction also applied only to OEM editions; retail Office license agreements allowed installing the product on two or three computers, depending on the edition.

Editions

Lineup of Microsoft Office 2013 icons, from left to right: Word, Excel, PowerPoint, Outlook, Access, OneNote, Publisher, Lync and InfoPath.

Traditional editions

As with previous versions, Office 2013 is made available in several distinct editions aimed towards different markets. All traditional editions of Microsoft Office 2013 contain Word, Excel,PowerPoint and OneNote and are licensed for use on one computer.

Five traditional editions of Office 2013 were released:

• Home & Student: This retail suite includes the core applications Word, Excel, PowerPoint, and OneNote.
• Home & Business: This retail suite includes the core applications Word, Excel, PowerPoint, and OneNote plusOutlook.
• Standard: This suite, only available through volume licensing channels, includes the core applications Word, Excel, PowerPoint, and OneNote plus Outlook and Publisher.
• Professional: This retail suite includes the core applications Word, Excel, PowerPoint, and OneNote plus Outlook, Publisher and Access.
• Professional Plus: This suite, only available through volume licensing channels, includes the core applications Word, Excel, PowerPoint, and OneNote plus Outlook, Publisher, Access, InfoPath and Lync.

Office 365

Main article: Microsoft Office 365

The Office 365 online services (previously aimed towards business and enterprise users) were expanded for Office 2013 to include new plans aimed at home use. The subscriptions allow use of the Office 2013 applications (along with other services) by multiple users using a software as a service model. Different plans are available for Office 365, some of which also include value-added services, such as 20 GB of SkyDrive storage (later increased to 1 TB) and 60 Skype minutes per month on the new Home Premium plan. These new subscription offerings were positioned as a new option for consumers wanting a cost-effective way to purchase and use Office on multiple computers in their household.

Office RT

A special version of Office 2013, initially known as Office 2013 Home & Student RT, is shipped with all Windows RT devices. It initially consisted of Word, Excel, PowerPoint and OneNote. In Windows RT 8.1, the suite was renamed Office 2013 RT and Outlook was added. The edition, whilst visually indistinguishable from normal versions of Office 2013, contains special optimizations for ARM-based devices, such as changes to reduce battery usage (including, for example, freezing the animation of the blinking cursor for text editing during periods of inactivity), enabling touch mode by default to improve usability on tablets, and using the graphics portion of a device's SoC for hardware acceleration.

Windows RT devices on launch were shipped with a "preview" version of Office Home & Student 2013 RT. The release date for the final version varied depending on the user’s language, and was distributed through Windows Update when released. On June 5, 2013, Microsoft announced that Windows RT 8.1 would add Outlook to the suite in response to public demand.

Office RT modifies or excludes other various features for compatibility reasons or resource reduction. To save disk space; templates, clip art, and language packs are downloaded online rather than stored locally. Other excluded features include the removal of support for third-party code such as macros/VBA/ActiveX controls, the removal of support for older media formats and narration in PowerPoint, editing of equations generated with the legacy Equation Editor, data models in Excel (PivotCharts, PivotTables, and QueryTables are unaffected), searching embedded media files in OneNote, along with data loss prevention, Group Policy support, and creating e-mails with information rights management in Outlook.

As the version of Office RT included on Windows RT devices is based off the Home & Student version, it cannot be used for "commercial, nonprofit, or revenue-generating activities" unless the organization has a volume license for Office 2013 already, or the user has an Office 365 subscription with commercial use rights.