Optical Transmission Upgrades: Why New Fiber Construction Remains Essential  

As artificial intelligence, high-performance computing, and cloud data centers continue to expand, global communication networks are entering a new round of upgrade cycles. In recent years, optical transmission technologies such as 800G, 1.6T, high-speed coherent optical communications, and ZR+ have achieved continuous breakthroughs, steadily increasing per-fiber transmission capacity and significantly improving network operational efficiency. However, from an industry development perspective, improvements in optical transmission capacity do not mean that demand for fiber construction will decline. On the contrary, new optical fiber networks will maintain a high level of construction intensity over the coming years and become an important part of digital infrastructure.

Optical Transmission Capacity Keeps Rising, Boosting Utilization of Existing Networks

In recent years, technology upgrades in the optical communications industry have centered on raising single-wavelength line rates, improving spectral efficiency, and reducing cost per unit of bandwidth.

Next-generation optical transmission solutions, represented by 800G and 1.6T high-speed optical modules, enable a single fiber to carry greater data traffic through higher-order modulation, more advanced digital signal processing (DSP), and higher-performance coherent optical communications. At the same time, the joint use of the C-band and L-band further expands the available spectrum, enabling substantial capacity gains on existing fibers without laying new cables.

For operators, this means existing fiber resources can be used more fully, per-fiber transmission efficiency keeps improving, and network expansion costs fall accordingly. In metro networks, backbone networks, and some data center interconnect scenarios, next-generation optical transmission systems have effectively postponed the need to build new routes, improving the value delivered by the entire network asset base.

Fiber Capacity Gains Are Approaching Physical Limits

Although optical communications technology continues to advance rapidly, the industry widely believes that its capacity headroom is gradually approaching theoretical limits.

Information transmission follows Shannon's information theory: given fixed spectrum resources and signal-to-noise ratios, the information capacity a single channel can carry has a theoretical upper limit. As modulation technologies keep advancing, optical communication systems are gradually approaching this limit, making it increasingly difficult to sustain capacity growth by raising single-wavelength line rates.

In other words, while technological innovation can still keep improving transmission efficiency, the capacity gain from each upgrade is steadily shrinking. When existing fiber resources approach their carrying limits, upgrading optical transmission equipment alone can no longer meet ever-growing data demand, and building new fiber networks will again become an important path to expansion.

High-speed optical communications technology therefore plays a greater role in improving network efficiency and extending the lifecycle of existing infrastructure than in replacing new fiber construction altogether.

New Data Centers Drive Sustained Growth in Fiber Demand

As hyperscale data centers continue to be built, data flow patterns are changing markedly.

In the past, most network traffic came from end users accessing internet services; in the future, traffic growth will come increasingly from large-scale interconnection among data centers. Training platforms, inference platforms, cloud computing resource pools, and distributed storage systems need to continuously exchange massive volumes of data, placing higher demands on network bandwidth.

Especially in large computing clusters deployed across regions, high-speed, low-latency transmission channels must be established between data centers to enable unified scheduling and resource sharing. This is making data center interconnect (DCI) an increasingly important direction for future network construction.

Current mainstream data center interconnect solutions generally adopt an IP-over-DWDM architecture: large numbers of 800G ZR+ coherent optical modules are deployed on switches or routers, and DWDM systems multiplex multiple high-speed optical signals onto fiber routes for high-speed data transmission across campuses, cities, and even regions.

As data centers keep growing in scale, interconnect bandwidth demand continues to rise, placing greater requirements on fiber resources and further driving the construction of long-haul cables and backbone fiber networks.

Metro, Backbone, and Submarine Networks Enter a Phase of Simultaneous Expansion

Future network expansion is not confined to the data center itself; it extends across the entire communications infrastructure system.

Metro networks must carry ever-growing data aggregation demand, backbone networks handle high-speed cross-regional transmission, and international data exchange depends on submarine cable systems for global interconnection.

As various digital services continue to grow, all of these networks must expand capacity in tandem, and upgrading optical transmission equipment alone cannot meet long-term demand. Future network construction will therefore follow a model that advances “equipment upgrades + new fiber construction” in parallel.

High-speed optical communications technology raises the value of each fiber, while new fiber construction supplies ever-growing physical transmission resources. The two complement each other and jointly underpin the future development of networks.

Power Supply Becomes a Key Constraint on Infrastructure Expansion

Compared with network equipment and fiber construction, power supply is increasingly becoming the critical factor constraining the development of large data infrastructure.

Fiber deployment, equipment upgrades, and network expansion can all be accomplished incrementally through sustained investment, but large data center construction requires not only network resources but also stable, ample energy supply. As computing scale keeps expanding, the electricity demand of a single data center is growing rapidly, and power availability in some regions has become a major constraint on project development.

Because grid construction cycles are long and new generation, transmission, and distribution capacity cannot be scaled up quickly, energy security will remain an important factor shaping the development of large digital infrastructure in the coming years.

Even as computing equipment becomes more energy-efficient and energy consumption per unit of compute continues to decline, rapid growth in overall business scale may offset these efficiency gains, keeping energy demand on the rise.

Optical Communications Enters a Phase Where “Capacity Enhancement” and “Infrastructure Expansion” Proceed in Parallel

Taking stock of industry trends, the future development of optical communications will be driven by two engines.

On one hand, 800G, 1.6T, high-speed coherent communications, ZR+, and more advanced optical transmission technologies will continue to increase network capacity, improve spectral efficiency, and lower cost per unit of bandwidth, making fuller use of existing fiber resources.

On the other hand, with hyperscale data center construction, growing cross-regional traffic, and the continuous upgrade of global digital infrastructure, technology upgrades alone can no longer satisfy long-term network demand. New fiber construction, backbone network expansion, and improved data center interconnect systems will remain key directions for future communications infrastructure development.

The focus of future network construction is no longer solely on raising per-fiber transmission capacity, but on forging a more coordinated development model between high-performance optical transmission technologies and continuously expanding fiber infrastructure, providing long-term, stable, and sustainable network support for ever-growing data exchange demand.