Photonics — the science and technology of generating, controlling, and detecting photons (particles of light) — is quietly replacing electronics in an expanding range of applications. From the fibre-optic cables that carry 95 percent of international data traffic to the laser-based sensors in autonomous vehicles, light-based technologies have become indispensable to modern civilisation. As electronic systems approach fundamental physical limits in speed and energy efficiency, photonics is emerging as the technology best positioned to power the next generation of computing, communications, and sensing.
From Electronics to Photonics
Electronic circuits transmit information using electrons flowing through copper wires and silicon transistors. While extraordinarily successful, this approach faces growing limitations. Electrons generate heat as they encounter resistance, limiting how densely transistors can be packed and how fast signals can travel. At the scale of modern microprocessors, these thermal and speed constraints are becoming critical bottlenecks.
Photons offer fundamental advantages. They travel at the speed of light, generate no heat during transmission, can carry multiple signals simultaneously at different wavelengths (a technique called wavelength-division multiplexing), and do not interfere with each other the way electrons do. A single optical fibre the diameter of a human hair can carry more data than thousands of copper wires combined.
Photonic Integrated Circuits
The most transformative development in photonics is the photonic integrated circuit (PIC) — a microchip that manipulates light rather than electricity. Just as electronic integrated circuits miniaturised transistors onto silicon chips in the 1960s, photonic integrated circuits are now placing lasers, modulators, waveguides, and detectors onto single chips using standard semiconductor fabrication techniques.
Silicon photonics, which builds photonic components on standard silicon wafers, is particularly promising because it leverages the massive existing infrastructure of the semiconductor industry. Companies including Intel, IBM, and Cisco are manufacturing silicon photonic transceivers for data centres, where they dramatically reduce energy consumption and increase bandwidth compared to electronic interconnects.
Applications Transforming Industries
In telecommunications, photonics is the foundation of the global internet. Undersea fibre-optic cables spanning thousands of kilometres carry virtually all international data traffic, with modern systems achieving transmission rates of hundreds of terabits per second per fibre. Advances in coherent optical transmission and spatial division multiplexing promise to increase this capacity by orders of magnitude.
In healthcare, photonics enables non-invasive diagnostic techniques from optical coherence tomography (OCT, used in ophthalmology) to photoacoustic imaging that combines light and sound to visualise tissues at depth. Laser surgery has become standard for vision correction, dermatology, and precision procedures where millimetre accuracy is essential.
LiDAR (Light Detection and Ranging) systems, which use pulsed lasers to create detailed 3D maps of surroundings, are critical sensors for autonomous vehicles and increasingly used in archaeology, forestry, urban planning, and environmental monitoring.
Photonic Computing and Quantum Technologies
Photonic processors designed specifically for AI computations can perform matrix multiplications — the core mathematical operations in neural networks — at the speed of light with minimal energy consumption. Several startups are developing commercial photonic AI accelerators that promise to process machine learning workloads orders of magnitude faster and more efficiently than electronic GPUs.
Photonics also underpins many quantum technologies. Photonic quantum computers use individual photons as qubits, photonic quantum networks transmit quantum information over long distances through optical fibres, and quantum sensors based on photonic interference achieve measurement sensitivities that classical devices cannot approach. As both classical and quantum photonic technologies mature, light is becoming the dominant medium for processing and transmitting information across the full spectrum of modern technology.
