What is an optical network?

Optical networking is a technology that uses light to transmit data between devices. It offers high bandwidth and low latency, and has been the de facto standard for long-distance data communications for many years. Fiber optics are used for most long-distance voice and data communications around the world.

Optical networking has a long history, and as its services and use cases expand, the trend to make it more flexible, intelligent and efficient will continue to grow.

Optical networking is important because it allows high-speed data transmission over long distances. For example, the optical network ensures that users in New York can access servers in Nairobi as fast as the laws of physics allow.

The technology behind optical networking is based on the principle of total internal reflection. When light hits the surface of a medium such as a fiber optic cable, some of the light is reflected by the surface. The angle at which light is reflected depends on the properties of the medium and the angle of incidence (the angle at which the light hits the surface).

If the angle of incidence is greater than the critical angle, then all light is reflected; this is called total internal reflection. Total internal reflection can be used to make optical fibers, a type of glass or plastic that guides light along its length.

As light travels through an optical fiber, it undergoes multiple total internal reflections, causing it to bounce off the fiber walls. This bouncing effect causes light to travel down the length of the fiber in a zigzag pattern.

By carefully controlling the properties of the fiber, engineers can control how much light is reflected and how far it travels before being reflected again. This allowed them to design optical fibers that could transmit data over long distances without any loss of information.

Optical networks consist of several components: optical fibers, transceivers, amplifiers, multiplexers, and optical switches.

optical fiber

Optical fiber is the medium that carries optical signals. It is composed of a variety of materials, including:

① Core: the center that carries light.

② cladding: the material that surrounds the core and helps to keep the optical signal contained.

③ Buffer coating: A material that protects optical fibers from damage.

The core and cladding are usually made of glass, while the buffer coating is usually made of plastic.

transceiver

Transceivers are devices that convert electrical signals to optical signals and vice versa, usually at the last mile of the connection. It is the interface between an optical network and the electronic devices that use it, such as computers and routers.

amplifier

As the name suggests, an amplifier is a device that amplifies light signals so they can travel long distances without losing strength. Amplifiers are placed at regular intervals along the fiber to boost the signal.

multiplexer

A multiplexer is simply a device that takes multiple signals and combines them into a single signal. This is done by assigning each signal a different wavelength of light, allowing a multiplexer to send multiple signals down a single fiber simultaneously without interference.

light switch

An optical switch is a device that routes optical signals from one optical fiber to another. Optical switches are used to control traffic in optical networks and are typically used in high-capacity networks.

History of Optical Networking

The history of optical networking begins in the 1790s when French inventor Claude Chappe developed the optical-signal telegraph, one of the earliest examples of an optical communication system.

Nearly a century later, in 1880, Alexander Graham Bell patented the phototelephone, an optical telephony system. While the Photophone was groundbreaking, Bell’s earlier inventions, the telephone, were more practical and took tangible form. So Photophone never left the experimental stage.

Until the 1920s, John Logie Baird in England and Clarence W. It was Hansell who patented the idea of using an array of hollow tubes or transparent rods to transmit images for television or fax systems.

In 1954, Dutch scientist Abraham Van Heel and British scientist Harold H. Hopkins have each published scientific papers on tractography. Hopkins focused on unclad fibers, while Van Heel only focused on simple clad fiber bundles—a transparent cladding with a lower refractive index around the bare fiber.

This protects the fiber reflective surfaces from external deformation and significantly reduces interference between fibers. The development of imaging bundles was an important step in the development of optical fibers. Protecting the fiber surface from external interference allows for more accurate transmission of optical signals through the fiber.

By 1960, glass-clad fiber had a loss of about 1 decibel (dB) per meter, suitable for medical imaging but too high for communications. In 1961, Elias Snitzer of American Optics published a theoretical description of an optical fiber with a tiny core that could transmit light through only one waveguide mode.

In 1964, Dr. Charles Kao proposed a light loss of 10 or 20 dB per kilometer. This standard helps to improve the range and reliability of telecommunication systems. In addition to his work on loss rates, Dr Gao also demonstrated the need for a purer glass to help reduce light loss.

In the summer of 1970, a team of researchers at the Corning Glass Works began experimenting with a new material called fused silica. This substance is known for its extreme purity, high melting point and low refractive index.

The team, consisting of Robert Maurer, Donald Keck, and Peter Schultz, quickly realized that fused silica could be used to make a new type of wire known as an “optical waveguide fiber.” This fiber-optic wire can carry 65,000 times more information than traditional copper wires. Furthermore, the light waves used to carry information can be decoded at destinations even a thousand miles away.

This invention revolutionized long-distance communication and paved the way for today’s fiber optic technology. The team solved the decibel loss problem defined by Dr. Gao, and in 1973 John MacChesney improved the chemical vapor deposition process for fiber production at Bell Laboratories. As a result, commercial production of optical fiber cables became possible.

In April 1977, General Telephone and Electronics used the fiber-optic network for the first real-time telephone communications in Long Beach, California. In May 1977, Bell Labs soon followed suit, building an optical telephone communication system spanning 1.5 miles in downtown Chicago. Each pair of optical fibers can transmit 672 voice channels, equivalent to a DS3 circuit.

In the early 1980s, the second generation of optical fiber communication was designed for commercial use, using 1.3 micron InGaAsP semiconductor lasers. These systems operated at bit rates of up to 1.7 Gbps in 1987, with repeater spacing of up to 50 kilometers.

The system used by the third-generation optical fiber network operates at 1.55 microns and has a loss of about 0.2 dB per kilometer.

Fourth-generation fiber optic communication systems rely on optical amplification to reduce the number of repeaters required, and wavelength division multiplexing (WDM) to increase data capacity.

In 2006, a bit rate of 14 terabits (Tb) per second was achieved on a 160 km line using optical amplifiers. As of 2021, Japanese scientists were able to transmit 319 Tbps over 3,000 kilometers using a four-core fiber optic cable.

Although the capacity of these fourth-generation fiber-optic communication systems is much greater than previous generations, the basic principle is the same: electrical signals are converted into pulses of light, sent through optical fibers, and then converted back to electrical signals at the receiving end.

However, with each generation the components become smaller, more reliable, and less expensive. As a result, fiber optic communications have become an increasingly important part of our global telecommunications infrastructure.

Major Trends in Optical Networking

Focus on the edge of the network

The optical network edge is where traffic enters and exits the network. In order to meet the needs of cloud-based applications, optical networks are moving closer to end users. This allows for lower latency and more consistent performance.

layer encryption

As cyberattacks become more common, data protection in motion will continue to be a major concern. SASE (Secure Access Service Edge), the use of cloud-native security features at service endpoints, has been gaining traction recently. Endpoint protection can make security controls on connected networks unnecessary.

While this may not eliminate the need for encryption, it will protect sensitive data and applications. Without a single security control, layer 1 protection becomes increasingly tricky.

We can better protect our resources by encrypting control, management, and user traffic. This makes it nearly impossible for hackers to break into the system, greatly reducing the chances of a successful cyber attack. As businesses rely more and more on data and connectivity, robust security solutions will only become more apparent.

Open Optical Network

An open optical network is an optical network that uses standard, open interfaces to allow integration of equipment from different vendors. This provides more choice and flexibility for optical network components. Plus, it makes it easier to add new features and services as they become available.

Spectrum Services Growth

As data traffic continues to grow, so does the need for higher bandwidth and capacity. Spectrum services provide this by using spectrum to increase the capacity of existing fiber optic networks. These services are growing in popularity as they provide a cost-effective way to meet growing data demands.

More outdoor deployment

Outdoor deployments in street cabinets are becoming more common as the need for higher bandwidth and capacity grows. Outdoor fiber can run directly to the user location, providing a more direct connection and lower latency.

compact modular

As optical networks continue to evolve, the need for smaller, more compact components is becoming more apparent. This is because space in a data center environment is often limited. Compact, modular optics provide a space-saving approach while still delivering high performance.

Future Development of Optical Networks

Intelligent Optical Network

An intelligent optical network is an optical network that uses artificial intelligence (AI) to optimize performance. Artificial intelligence can be used to automatically identify and correct problems in the network. This allows for a more efficient and reliable network.

Additionally, AI can be used to predict future traffic patterns and demand. This information can be used to provision capacity ahead of time, ensuring that the network can meet future demands.

Flexible Grid Architecture

Flexible mesh architectures are becoming more popular because they provide a way to increase the capacity of existing fiber optics. A flexible grid allows multiplexing of different wavelengths of light on a single fiber. This allows more data to be carried on each fiber, increasing network capacity.

WDM on demand

Wavelength division multiplexing is a technology that allows multiple wavelengths of light to be transmitted on a single optical fiber. On-demand WDM is a type of WDM that allows capacity to be provided on demand. This means that capacity can be added as needed without installing new fiber optics.

Optical Networking in an Increasingly Digital World

Optical networking has come a long way in its relatively short history. From humble beginnings, it is now an essential part of many large network infrastructures. It is a key pillar of the Internet, revolutionizing the way we communicate and ushering in an era of unprecedented technological advancement.

As trends such as 5G mature, optical networking appears poised to continue playing an important role in our increasingly digital world.