In today’s hyper-connected world, every phone call, website visit or video download is powered by beams of light racing through optical fibre strands that are as thin as hair. These remarkable fibres transmit data, voice and video signals at near-instant speeds.
This scientific breakthrough is the backbone of our modern network infrastructure that connects billions of people across the globe.
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Science behind optical fibres
Optical fibre technology uses the principles of light reflection to transmit data. Information is encoded into pulses of light, which is sent from one end of the fibre and travels through the core to the other end.
An optical fibre consists of a glass or plastic core with a higher refractive index, surrounded by a cladding layer with a lower refractive index.
This difference between the core and the cladding’s refractive indices decides the critical angle at the boundary between the two materials.
The optical fibre’s critical angle is the point where
light stops refracting – bending and going through the cladding – and instead is completely reflected, bouncing back into the core. Thus, when light hits the boundary between the core and cladding at an angle greater than the materials’ critical angle, the light reflects back into the core (see graphic).
This phenomenon, known as total internal reflection, allows light to travel along the fibre over vast distances with minimal loss of signal.
A milestone in communication
The idea to use light to transmit information dates back over a century, but the true breakthrough came in the 1960s, thanks to the pioneering work of Charles Kao – who grew up in Hong Kong – and his colleague George Hockham.
Before their discovery, copper wires and early glass fibres were used to send data, but these had issues with signal loss during transmission.
In Kao and Hockham’s research paper published in 1966, they explained that signal loss during transmission was mainly caused by impurities in the glass. By proposing the use of fibres made of ultra-pure glass, they paved the way for the development of optical fibres that minimised signal loss. This made high-speed, long-distance communication a reality.
They discovered that purified glass fibres could send light signals over great distances with minimal loss.
Kao made this groundbreaking discovery while working at the Standard Telecommunications Laboratories in the UK. His research earned him the Nobel Prize in Physics in 2009, and he became widely recognised as the “father of fibre optics”.
Endless possibilities
Optical fibre technology has revolutionised the way we communicate and connect. Compared to copper cables and early glass fibres, optical fibres allow us to send much more data at higher speeds. It is also less susceptible to electromagnetic interference.
Optical fibres have a wide range of applications. They are used in telecommunications for high-speed global data transmission, in medicine for real-time imaging during surgeries, and in planes and cars which use remote sensing to warn operators about problems.
As technology continues to advance, its potential applications keep expanding, transforming industries and enhancing lives with limitless possibilities for the future.
Young Post has partnered with Hong Kong Science Museum and Hong Kong Space Museum to encourage your pursuit of science. Every month, the museums answer questions about the world around us, the cosmos and beyond.
