A glimpse into optical engineering

Optical engineering is the engineering discipline that focuses on the design of equipment and devices that function by using light. It is based on the science of optics, a field of physics that studies the properties and behaviors of visible light. This field is important to a very wide array of technologies, including optical instruments such as microscopes and binoculars, lasers, and many commonly used electronic and communication devices.

Optical engineering is essential to fiber-optic technology, which transmits information through cables using pulses of light instead of electricity. Optical fibers are flexible materials that can be used as waveguides, materials that can guide the direction of light. They guide light as it travels by taking advantage of a phenomenon called total internal reflection, which keeps the light channeled down the core of the fiber. The design of optical fibers requires an understanding of how light is refracted as it moves through different media.

The global optical networking market is poised to hit revenues of US$ 24 Bn towards the end of 2029. 5G will be relying on fiber as an advanced radio technology to deliver front haul for Cloud-RANs (radio access networks) and backhaul for dense, fast networks. 5G wireless network brings to optical networking new requirements such as high bandwidth, low latency, accurate synchronization, and the ability to perform network slicing.

The requirement for high bandwidth is driven by emerging wireless applications such as massive multiple-input-multiple-output (MIMO), whereas the requirements for low latency and accurate synchronization are driven by cloud radio access network (C-RAN) and coordinated multi-point (CoMP). Fiber-optical communications benefited from scientific advances in the field of optics, photonics, electronics, and digital signal processing (DSP).

Fiber-optic transmission systems and networks are expected to continue to evolve to offer higher capacity and wider application space, especially through interworking with wireless networks. The three main features of future optical networks in the decade of 2020s are: enhanced fiber transmission capacity (eFTC), massive optical cross-connections (mOXC), and intelligent network operation and maintenance (iO&M).

To meet the demands of enhanced mobile broadband (eMBB) in 5G, optical networks need to provide more transmission capacity and do so cost-effectively. This calls for enhanced fiber transmission capacity (eFTC). The key is to increase per-fiber capacity, by fully utilizing the following four physical dimensions of a light wave traveling along a fiber transmission link: amplitude and phase of a given optical carrier, polarization-division multiplexing (PDM), wavelength-division multiplexing (WDM), and Space-division multiplexing (SDM).

Generally, there are three basic physical attributes of a light wave that can be modulated to carry information, its amplitude, phase, and polarization. There are three popular modulation and detection schemes: intensity modulation and direct detection (IM/DD), differential phase keying (DSPK), and coherent optical modulation and detection. For IM/DD, the most common optical modulation format is on-off-keying (OOK), in which the light intensity is turned on and off to represent the “1” and “0” states of a digital signal.

Mobile network applications have a diverse set of demands such as ultra-low latency, ultra-high availability, ultra-large bandwidth, and overall optimization of the entire network. With the use of software-defined network (SDN), intelligent optical networks can be built with the network virtualization and slicing capabilities for 5G.

C-RAN is playing an important role in mobile networks by improving network performance via CoMP and increasing network energy efficiency via capacity sharing and optimization. Mobile fronthaul is a key network element in the C-RAN architecture, as it connects centralized baseband units (BBUs) with remote radio units (RRUs). The interface for mobile fronthaul is primarily based on the common public radio interface (CPRI) and the evolved CPRI (eCPRI) via a point-to-point (PTP) architecture.

Mobile front-haul could also be used to support massive multiple-input-multiple-output (M-MIMO), which is considered as another key technology for 5G networks. On the other hand, mobile back-haul connects BBUs with the core networks to transport the baseband data streams to their respective destinations.

As the capacity of reconfigurable optical add/drop multiplexer (ROADM) or optical cross-connect (OXC) continues to evolve, existing technologies are enough to meet the capacity requirements of evolving optical nodes for the next 3 years. Although it's unknown which technologies will be used to meet capacity requirements thereafter, future traffic demand will move toward ultra-large capacity, ultra-high-speed, and ultra-long-haul transmission.

Glow’s role

Here at Glow, we help with design, market and technology-analysis services, meeting specific requirements for equipment vendors and customers in fiber network consultation, and network engineering. We offer a host of services including design, engineering, optical networks intelligence services, fiber characterization, splicing and testing.