Optical networking is a technology that uses optical signals to transmit data through fiber optic cables. It consists of a system of components including optical transmitters, optical amplifiers and fiber optic infrastructure to facilitate high-speed communications over long distances.

This technology supports the transmission of large amounts of data at high bandwidth, enabling faster and more efficient communications compared to traditional copper cable networks.

Main components of optical networks

The main components of an optical fiber network include optical fiber cables, optical transmitters, optical amplifiers, optical receivers, transceivers, wavelength division multiplexing (WDM), optical switches and routers, optical cross-connects (OXCS), and optical add-subtract multiplexers.

optic fibre cable

Fiber optic cable is a high-capacity transmission medium made of glass or plastic called optical fiber.

These optical fibers carry optical signals over long distances with minimal signal loss and high data transmission rates. The core of each fiber is wrapped with a cladding material that reflects the optical signal back to the core for efficient transmission.

Compared with traditional copper cables, fiber optic cables have the advantages of resisting electromagnetic interference and reducing signal attenuation, and have been widely used in telecommunications and network applications.

Optical transmitter

Optical transmitters convert electrical signals into optical signals, which are transmitted through fiber optic cables. Its primary function is to modulate a light source, usually a laser diode or light-emitting diode (LED), in response to an electrical signal representing data.

optical amplifier

Optical amplifiers are strategically placed on fiber optic networks to enhance optical signals and maintain signal strength over longer distances. This component compensates for signal attenuation and allows signal transmission over distances without expensive and complex optical-to-electrical signal conversion.

The main types of optical amplifiers include:

• Erbium-doped fiber amplifier (EDFA): EDFA uses erbium-doped fiber. When exposed to light of specific wavelengths, erbium ions in the fiber absorb and re-emit photons, amplifying the optical signal. EDFA is commonly used in the 1550nm range and is a key component for long-distance communications.
• Semiconductor optical amplifier (SOA): SOA amplifies optical signals through semiconductor materials. The incoming light signal induces stimulated emission inside the semiconductor, resulting in signal improvement. SOA is designed for short distance and access network scenarios.
• Raman amplifiers: Raman amplifiers exploit the Raman scattering effect in optical fibers. Pump light of different wavelengths interacts with the optical signal, transferring energy and enhancing it. This type of amplifier is versatile and can operate at a variety of wavelengths, including the commonly used 1550 nm range.

optical receiver

At the receiving end of the optical link, an optical receiver converts the incoming optical signal back into an electrical signal.

transceiver

A transceiver is a multifunctional device that combines the functions of an optical transmitter and receiver into a single unit, facilitating two-way communication over a fiber optic link. They convert electrical signals into optical signals for transmission, and convert received optical signals back into electrical signals.

Wavelength Division Multiplexing (WDM)

Wavelength division multiplexing (WDM) allows multiple data streams to be transmitted simultaneously on a single optical fiber. The basic principle of WDM is to use light of different wavelengths to carry independent data signals, supporting the increase in data capacity and the effective use of spectrum.

WDM is widely used in long-haul and metro optical networks, providing a scalable, cost-effective solution to meet the growing needs for high-speed, large-capacity data transmission.

Optical Add-Subtract Multiplexer

Optical add-subtract multiplexers (OADMS) are the main components in WDM optical networks, providing the ability to selectively add (inject) or reduce (extract) optical signals of specific wavelengths at network nodes. OADMS helps optimize data flow in the network.

Optical switches and routers

Both optical switches and routers contribute to the development of advanced optical networks, providing solutions for high-capacity, low-latency and scalable communication systems to meet the ever-changing needs of modern data transmission.

Optical switches selectively route optical signals from one input port to one or more output ports. They are very important for establishing communication paths in optical networks. These devices work by controlling the direction of light signals without converting them into electrical signals.

Optical routers, on the other hand, direct packets at the network layer based on the destination address. They operate in the optical domain, maintaining the integrity of the optical signal without converting it into electrical form.

Optical Cross Connect (OXCS)

Optical cross-connects (OXCs) enable the reconfiguration of optical connections by selectively routing signals from input fibers to the desired output fibers. By simplifying wavelength-specific routing and rapid reconfiguration, OXCS helps improve the flexibility and low-latency characteristics of advanced optical communications systems.

How optical networks work

The function of optical networks is to use optical signals to transmit data through fiber optic cables, creating a fast communication framework. The process includes optical signal generation, optical transmission, data encoding, optical propagation, signal reception and integration, and data processing.

Optical signal generation

Optical networks first convert data into pulses of light. This conversion is typically accomplished using a laser source to ensure successful representation of the information.

Optical transmission

During this stage, the system sends pulses of light carrying data through fiber optic cables. Light travels within the core of the cable, bouncing off the surrounding cladding due to total internal reflection. This allows light to travel great distances with minimal loss.

Data encoding

The data is then encoded onto the light pulses, introducing changes in the intensity or wavelength of the light. This process is tailored to business application needs and ensures seamless integration with the optical network framework.

light propagation

Pulses of light travel through fiber optic cables, providing high-speed, reliable connections within the network. This makes the transfer of important information between locations faster and more secure.

Signal reception and integration

At the receiving end of the network, light-sensitive devices, such as photodiodes, detect the incoming light signal. Photodiodes then convert these light pulses back into electrical signals, improving the integration of optical networks.

data processing

The electrical signals are further processed and interpreted by electronic equipment. This stage includes decoding, error correction, and other operations necessary to ensure the accuracy of data transmission. The processed data is used in a variety of operations to support critical functions such as communication, collaboration, and data-driven decision-making.

8 types of optical networks

There are many different types of optical networks that serve different purposes. The most commonly used ones are mesh networks, Passive Optical Networks (PON), Free Space Optical Networks (FSO), Wavelength Division Multiplexing (WDM) networks, Synchronous Optical Networks (SONET) and Synchronous Digital Hierarchy Networks (SDH), optical Transport Network (OTN), Fiber to the Home (FTTH)/Fibre to the Premises (FTTP) and Optical Cross Connect (OXC).

1. Mesh network

Optical mesh networks interconnect nodes through multiple fiber optic links. This provides redundancy and allows traffic to be dynamically rerouted in the event of a link failure, enhancing network reliability.

• Typical applications: Typically used in large-scale mission-critical applications where network resiliency and redundancy are essential, such as in data centers or core backbone networks.

2. Passive Optical Network (PON)

PON is a fiber optic network architecture that delivers fiber optic cables and signals to end users. It uses unpowered optical splitters to distribute the signal to multiple users, making it passive.

• Typical applications: "last mile" connectivity, providing high-speed broadband access to residential and commercial users.

3. Free space optical communication (FSO)

FSO uses free space to transmit optical signals between two points.

• Typical applications: High-speed communications in environments where fiber optic deployment is impractical or difficult, such as urban areas or military purposes.

4. Wavelength Division Multiplexing (WDM)

WDM uses different wavelengths of light for each signal, thereby increasing data capacity. Subtypes of wavelength division multiplexing include coarse wavelength division multiplexing (CWDM) and dense wavelength division multiplexing (DWDM).

• Typical applications: CWDM is used for short-distance metropolitan area networks, and DWDM is used for long-distance, large-capacity communications.

5. Synchronous Optical Network (SONET)/Synchronous Digital Hierarchy (SDH)

SONET and SDH are standardized protocols for transmitting large amounts of data over long distances using fiber optic cables. SONET is more commonly used in North America, while international industry uses SDH.

• Typical applications: SONET and SDH are designed for high-speed, long-distance voice, data and video transmission. They provide a synchronized and reliable transport infrastructure for telecommunications infrastructure and carrier networks.

6. Optical transmission network (OTN)

OTN transmits digital signals at the optical layer of the communication network. It has functions such as error detection, performance monitoring and fault management.

• Typical applications: used with WDM to maximize the resiliency of long-distance transmission.

7. Fiber to the home (FTTH)/fiber to the home (FTTP)

FTTH and FTTP refer to the direct deployment of fiber optics to residential or commercial locations to provide high-speed Internet access.

• Typical applications: FTTH and FTTP support bandwidth-intensive applications such as video streaming, online gaming and other broadband services.

8. Optical cross-connect (OXC)

OXC makes the exchange of optical signals easier without the need to convert optical signals into electrical signals.

• Typical applications: Mainly used by telecom operators for traffic management in large optical networks.

Today’s use of optical networks

Today, many industries and fields are using optical networks for high-speed and efficient data transmission. These include telecommunications, healthcare, financial institutions, data centers, internet service providers (ISPs), enterprise networks, 5G networks, video streaming services and cloud computing.

telecommunications

Optical networks are the basis of telephone and Internet systems. Today, optical networks remain key to telecommunications, connecting cell sites, ensuring high availability through dynamic traffic rerouting, and enabling high-speed broadband in metro and long-haul networks.

medical insurance

For healthcare, optical networks ensure fast and secure transmission of medical data, accelerating remote diagnosis and telemedicine services.

Financial Institutions

Financial institutions leverage this technology for fast and secure data transfer, which is essential for activities such as high-frequency trading and seamless branch-to-branch connections.

data center

Optical networks in data centers connect servers and storage units, providing a high-bandwidth and low-latency infrastructure for reliable data communications.

internet service provider

Internet service providers utilize optical networks to provide broadband services, using fiber optic connections for faster access to the Internet.

Enterprise network

Large enterprises leverage internal optical networks to connect offices and data centers to maintain high-speed and scalable communications within their infrastructure.

Mobile network (5G)

For 5G mobile networks, optical networks allow for increased data rates and low latency requirements. Fiber optic connections connect 5G cell sites to the core network, bringing bandwidth to a variety of applications.

video streaming services

Optical networks enable smooth data transmission, delivering high-quality video content through streaming platforms for a more active viewing experience.

cloud computing

Cloud service providers rely on optical networks to connect data centers to deliver scalable, high-performance cloud services.

The history of optical networks

The combined efforts of several optical networking companies and prominent individuals have significantly shaped the optical networking landscape as we know it today.

• 1792: French inventor Claude Chappe invented the optical telegraph, one of the earliest optical communication systems.
• 1880: Alexander Graham Bell patented the optical telephone system. However, its first invention, the telephone, was considered more practical.
• 1965: German physicist Manfred Börner demonstrates the first working fiber optic data transmission system at the Telefunken research laboratory in Ulm.
• 1966: Sir Charles K. Kao and George A. Hockham proposed that optical fiber made of ultrapure glass could transmit distances of several kilometers without completely losing the signal.
• 1977: General Telephone and Electronics Corporation tests and deploys the world's first commercial fiber-optic network for long-distance communications.
• 1988-1992: The emergence of the SONET/SDH standard.
• 1996: The first commercial 16-channel DWDM system is launched by Ciena.
• 1990s: Organizations begin using fiber optics to connect Ethernet switches and IP routers in corporate local area networks (LANs).

Rapidly expand optical networks to support the growing demands of the Internet boom.

Organizations are starting to use optical amplification to reduce the need for repeaters, and more businesses are implementing WDM to increase data capacity. This marked the beginning of optical networking, as WDM became the technology of choice for extending the bandwidth of fiber optic systems.

• 2000: The bursting of the dot-com bubble leads to the decline of the optical networking industry.
• 2009: The term software-defined networking (SDN) is first coined in an MIT review article.
• 2012: Network Function Virtualization (NFV) was first proposed by the European Telecommunications Standards Institute (ETSI) at the OpenFlow World Congress, which is composed of service providers such as AT&T, China Mobile, British Telecom Group, and Deutsche Telekom.
• Current status: 5G becomes operational in 2020.

Research and development in photonic technology continues. Photonics solutions have more reliable laser capabilities and can transmit light at historic speeds, allowing device manufacturers to unlock a wider range of applications and prepare next-generation products.

Optical network development trends

Optical network development trends such as 5G convergence, elastic optical networks, optical network security, data center interconnection, and green networking highlight the continuous evolution of optical network technology to meet the needs of new technologies and new applications.

5G integration

Optical networks can provide high-speed, low-latency connections to meet the data needs of 5G applications. 5G integration ensures you have fast and reliable connectivity for activities like streaming, gaming, and emerging technologies like augmented reality (AR) and virtual reality (VR).

Advances in coherent optics

Continuing advances in coherent optics technology are helping to enable higher data rates, longer transmission distances and increased optical network capacity. This is critical to accommodate growing data traffic and support applications that require high bandwidth.

edge computing

The integration of optical networks with edge computing reduces latency and improves the performance of applications and services that require real-time processing. This is essential for applications and services that require real-time response, such as self-driving cars, telemedicine procedures, and industrial automation.

Software Defined Networking (SDN) and Network Functions Virtualization (NFV)

By adopting SDN and NFV in optical networks, you can achieve better flexibility, scalability and effective utilization of resources. This allows operators to dynamically allocate resources, optimize network performance, and respond quickly to changing demands, thereby improving overall network efficiency.

Resilient Optical Network

Resilient optical networks allow the spectrum and capacity of optical channels to be dynamically adjusted based on business needs. This promotes optimal use of resources and minimizes the risk of congestion during peak usage.

Optical network security

Focusing on strengthening the security of optical networks, including encryption technology, is important to protect sensitive data and communications. As cyber threats become more sophisticated, protecting their networks becomes critical, especially when transmitting sensitive information.

Optical interconnect for data centers

The demand for cloud computing, big data processing and artificial intelligence applications has driven the growing demand for high-speed optical interconnects in data centers. Optical interconnects have the bandwidth to handle large amounts of data in data center environments.

green network

Efforts to make optical networks more energy efficient and environmentally friendly are in line with broader sustainability goals. Green network practices play a key role in reducing the environmental impact of telecommunications infrastructure, making it more sustainable in the long term.

Summary: Optical networks are here to stay

The development of optical networks has played an important role in shaping the history of computer networks. As computer networks evolve, the need for faster data transmission methods continues to grow, and optical networks provide a solution. By using light for data transmission, this technology enables the high-speed networks used today.

As fiber optic networks grow, they do more than just provide faster internet speeds. For example, optical network security can protect their organizations from emerging cyber threats, while trends such as green networking can make telecom infrastructure more sustainable over time.