Mention semiconductors to the general public, and the image that usually comes to mind is a silicon chip foundry in Taiwan or South Korea. That is understandable. Advanced silicon manufacturing dominates headlines and investment.

Yet it tells only part of the story. A large and growing segment of the semiconductor world looks very different. It centres on optoelectronics, the semiconductors that emit, detect or manipulate light. These devices underpin the wider photonics industry, which builds complete systems for generating, controlling and using light.

Photonics is increasingly recognised as a strategic technology platform that underpins modern communications, sensing, healthcare and advanced computing. In the UK alone, the sector already generates £18.5 billion ($24.9bn) in annual turnover and contributes £8.6 billion ($11.58bn) to the economy, according to a February 2026 report by the Council for Science and Technology.

The foundation of many photonic systems lies in the optoelectronic semiconductor components embedded inside them. These include lasers, LEDs, photodetectors, and sensor arrays that convert electricity into light, or light into electrical signals.

Understanding and advancing these semiconductor building blocks will be central to the next phase of photonics innovation. Equally critical is developing the processes to integrate them into complete photonic systems.

Two sides of the same technology

Photonics can be thought of as the system-level technology of light. It includes optical fibers, lenses, waveguides, sensors, and integrated photonic circuits that control how light travels and interacts with matter.

Optoelectronics refers more specifically to the semiconductors that generate or detect that light.

These two domains have always been closely connected, but historically they were often developed separately. Photonic systems might contain discrete lasers or detectors connected through optical components assembled at the packaging stage.

The future of photonics looks different. Increasingly, the industry is moving towards photonic integration, where optoelectronic semiconductors are combined directly with photonic circuits on a single platform.

This approach promises smaller, faster, and more energy-efficient systems. It is particularly attractive for applications such as optical communications, sensing, and emerging technologies such as optical computing.

But achieving this integration is technically demanding.

The integration challenge

Silicon-based photonics is a core technology, where semiconductor foundry processes can be used to manufacture optical circuits on the same platform as semiconductor devices. Silicon is an excellent platform for carrying light through waveguides and for integrating electronics. But silicon has one crucial limitation – an indirect bandgap means it cannot efficiently emit light.

For that reason, many optoelectronic devices rely on other semiconductor materials such as gallium arsenide, indium phosphide, or gallium nitride.

The critical step for the future of photonics is therefore heterogeneous integration: combining different semiconductor materials and photonic structures in a single integrated system.

In practical terms, this might mean placing a light-emitting semiconductor laser directly onto a silicon photonic chip, or integrating arrays of photodetectors alongside optical waveguides.

The potential advantages are considerable. Integrated photonic systems could transform data communications, sensing, and computing by increasing speed, reducing power consumption, and shrinking system size.

However, this step also introduces new scientific and manufacturing challenges.

Measurement at the heart of innovation

At first glance, the main obstacle might appear to be materials engineering. In reality, measurement science is the critical enabler.

Heterogeneous photonic systems involve multiple materials, microscopic optical structures, and delicate interfaces between components. Tiny variations in alignment, strain, or material quality can completely compromise how light is generated, transmitted, or detected.

This creates a complex metrology problem.

To manufacture integrated photonic systems reliably, engineers must be able to measure optical, electrical, and structural properties across several different materials and components simultaneously. They must also understand how these properties interact once the system is assembled.

Measurement, therefore, becomes a fundamental part of effective innovation. Without reliable ways to measure device behaviour, new photonic architectures are difficult to optimize, compare, or scale into manufacturing.

The challenge becomes even clearer when considering the two broad classes of optoelectronic devices mentioned above- light-emitting devices (essential for optical communications, displays, and emerging applications such as optical computing) and light-detecting devices (used in everything from cameras and autonomous systems to medical diagnostics).

Both categories must operate with extreme precision. Light sources must produce stable wavelengths and power levels. Detectors must measure faint signals accurately and consistently. When these components are integrated into photonic circuits, measurement becomes even more complex.

A strategic opportunity

For countries seeking a role in the future of semiconductors, this shift in technology architecture creates an opportunity.

The global race for leading-edge silicon manufacturing is dominated by a handful of large economies. Photonics and optoelectronics present a different landscape.

The UK has long-standing strengths in photonics and optoelectronic research, compound semiconductor manufacturing, and semiconductor processing equipment. Universities and companies across the country contribute to technologies ranging from optical fibers and lasers to quantum photonics and imaging systems.

As the photonics sector evolves toward integrated photonic systems, these capabilities can become strategically important. The ability to measure and validate complex photonic devices will help determine which technologies move from research laboratories into commercial deployment.

In other words, leadership in measurement science can shape how the next generation of photonic technologies develops.

From components to systems

The photonics industry is often described in terms of the systems it enables, from faster communications networks to advanced sensors and medical imaging.

Yet those systems ultimately depend on the performance of the semiconductor devices inside them.

Recognizing the relationship between photonics and optoelectronics, therefore, matters. Photonics may be the visible industry. Optoelectronic semiconductors are the engines that make it work.

As photonic systems become more integrated, the ability to measure these semiconductor components and their interactions within complex optical systems will only grow in importance.

In the coming decade, the success of photonics may depend as much on measurement science as on materials or design.

And that is precisely where the next competitive advantage may lie.