What is 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 is used for most long-distance voice and data communications around the world.

Optical networks have a long history, and the trend to make them more flexible, intelligent, and efficient will continue to grow as their services and use cases expand.

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

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

If the angle of incidence is greater than the critical angle, then all of the light is reflected; this is called total internal reflection. Total internal reflection can be used to make optical fiber, 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's walls. This bouncing effect causes the light to propagate down the length of the fiber in a zigzag pattern.

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

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

optical fiber

Optical fiber is the medium that carries light signals. It is made up of a variety of materials, including:

• Core: The center that carries the light.
• Cladding: The material that surrounds the core and helps keep the light signal contained.
• Buffer Coating: Material that protects optical fiber from damage.

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

Transceiver

A transceiver is a device that converts electrical signals into optical signals and vice versa, and is usually implemented at the last mile of a connection. It is the interface between the 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 optical 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 a different wavelength of light to each signal, allowing the multiplexer to send multiple signals along a single optical fiber at the same time without interference.

Optical 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 networks began in the 1790s when French inventor Claude Chappe invented 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 Photophone, an optical telephone system. While the Photophone was groundbreaking, Bell’s earlier inventions were more practical and took a tangible form. As such, the Photophone never left the experimental stage.

It wasn't until the 1920s that John Logie Baird in England and Clarence W. Hansell in the United States patented the idea of ​​using arrays 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 each published a scientific paper on fiber bundle imaging. Hopkins focused on unclad optical fibers, while Van Heel focused only on simple clad fiber bundles—a transparent cladding with a lower refractive index surrounding a bare optical fiber.

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

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

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

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

The team, consisting of Robert Maurer, Donald Keck, and Peter Schultz, soon realized that fused silica could be used to create a new type of wire called "optical waveguide fiber." This fiber-optic line could carry 65,000 times more information than conventional copper wire. Furthermore, the light waves used to carry the information could be decoded at their destination even a thousand miles away.

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

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

In the early 1980s, second-generation fiber-optic communications were designed for commercial use, using 1.3-micron InGaAsP semiconductor lasers. These systems operated at bit rates up to 1.7 Gbps in 1987 with repeater spacings up to 50 km.

Third-generation fiber networks use systems operating at 1.55 microns, with 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 over a 160 km line using optical amplifiers. As of 2021, Japanese scientists were able to transmit 319 Tbps over 3,000 km using a four-core fiber optic cable.

While 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 an optical fiber, and then converted back into electrical signals at the receiving end.

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

Key Trends in Optical Networking

Focus on the network edge

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

Layer Encryption

As cyberattacks become more common, protection of data in motion will continue to be a major concern. SASE (Secure Access Service Edge), the use of cloud-native security capabilities at service endpoints, has gained traction recently. Endpoint protection may 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, protecting Tier 1 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 cyberattack. As businesses become more dependent on data and connectivity, strong security solutions will only become more evident.

Open Optical Network

Open optical networking 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. It also makes it easier to add new features and services as they become available.

Growth of spectroscopy services

As data traffic continues to grow, the need for higher bandwidth and capacity is also increasing. Spectrum services provide this by using light spectrum to increase the capacity of existing fiber networks. These services are becoming increasingly popular because they provide a cost-effective way to meet growing data demands.

More outdoor deployments

As the demand for higher bandwidth and capacity grows, outdoor deployments in street cabinets are becoming more common. Outdoor fiber can be 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 becomes more apparent. This is because space is often limited in data center environments. Compact modular optical components offer a way to save space while still providing high performance.

Future Development of Optical Networks

Intelligent Optical Network

Intelligent optical networks are optical networks that use artificial intelligence (AI) to optimize performance. AI can be used to automatically identify and correct problems in the network. This allows for a more efficient and reliable network.

In addition, AI can be used to predict future traffic patterns and demand. This information can be used to configure capacity in advance, ensuring that the network can meet future demand.

Flexible grid architecture

Flexible mesh architectures are becoming increasingly popular because they offer a way to increase the capacity of existing optical fibers. Flexible meshes allow different wavelengths of light to be multiplexed 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. WDM on demand is a type of WDM that allows capacity to be provided on demand. This means that capacity can be increased as needed without installing new optical fiber.

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 a critical component of many large network infrastructures. It is a key backbone of the Internet, has revolutionized the way we communicate, and has ushered in an unprecedented era of technological advancement.

As trends like 5G mature, optical networks appear poised to continue playing a vital role in our increasingly digital world.