Optics and photonics

Although the general public is likely to associate "optics" with telescopes and contact lenses, the applications and the underpinning science of optics and photonics are much broader in scope and much more dynamic as a research discipline. A diverse range of the industries rely heavily on optics and photonics and they continue to prosper and grow. The new technologies emerging from research laboratories and universities mean that this growth is sure to continue into the future.

 

Optical technologies are the basis of many of today's popular and powerful technologies: the small semiconductor laser in your CD player and the fibre optic network connecting you to the Internet both rely on developments in optics. Soon, research currently underway may enable computers using optical technology to help solve difficult problems such as weather forecasting.

 

Optical sciences deal with the study of light and its behaviour (although by "light" we often mean the near infra red and ultraviolet, as well as the visible spectrum). The long established traditional areas of optical science are geometrical optics (how light is reflected and refracted by media - critical to the correct design of optical systems) and physical optics (which is concerned with the nature and properties of light). These remain a vital and active area of research and application. For example, adaptive optical systems, which use computer-controlled optical elements to eliminate aberrations or distortions introduced by atmospheric disturbances are already being used by astronomical telescopes and may be used to improve vision. However, there are many other exciting and innovative areas where development relies heavily on research in the fields of optics and photonics.

 

Recent applications of optical research result from work on new light sources and new material to manipulate light. Solid-state light sources (light emitting diodes - LEDs - and lasers) use semiconductor technologies to produce light sources that are small, controllable and can be integrated within electronic systems. LEDs, with their low power consumption, small size and bright light are ubiquitous on watches, microwave ovens and car dashboards, yet they only began to be used widely in commercial applications in the 1970s. Future applications abound, in particular research to develop white light LEDs which will replace fluorescent tubes and general lighting. With lower power consumption and longer life, the 20 - 30% of electricity generated for lighting can be significantly reduced, with obvious savings in cost and greenhouse gas emissions.

 

Another major application for light sources is in optical communication networks. Light, due to its higher frequency, offers incredible increases in the amount of information that it can carry compared with radio or satellite systems. This light can be carried around the globe using fibre optic networks. Fibre optic is a fine strand of glass tailored so that light that enters the fibre remains within it. A piece of fibre optic is one thousandth of a millimeter in diameter and, coupled with the appropriate light source, can carry the equivalent of 30,000 telephone calls simultaneously!

 

The purity of the glass in fibre optic is such that if the wavelength of the light is in the near-infrared, the light signal is able to travel many hundreds of kilometers before needing to be amplified. However, to amplify an optical signal you need to convert it to an electrical signal, amplify the signal and then convert it back to an electrical signal, amplify the signal and then convert it back to an optical signal. In so doing, the speed and capacity of the network is reduced. Research and development is concentrating upon all optical systems. As well as all-optical amplifiers which are beginning to be deployed (removing the need to convert the signal back to the electrical domain) optical switches (the heart of a telecommunications network) and other optical components will significantly improve the capabilities of telecommunication systems, as well as grow new businesses to develop and build the all-optical networks.

 

Solid-state lasers are ideal when you only need low power. Many interesting physics problems demand higher powers or exceptionally short pulses. High power lasers are used to study the properties of plasmas and to understand the properties of `processes in extreme conditions. Ultra-short laser pulses can study interactions between light and matter and are finding many applications in the study of chemical and biological systems. New surgical techniques use ultra-short laser pulses to safely remove tissue without damaging the surrounding body.

 

As well as industry demanding innovative ideas and highly skilled graduate scientists and engineers, there is much leading edge research in universities and laboratories worldwide. Quantum cryptography uses the theory of the quantum mechanical properties of light to encrypt messages (or their keys - the information needed to decode a message) so that they cannot be intercepted without revealing the interference to the sender. Reports on the first experimental verifications of these ideas are beginning to appear.

 

Laser technology has enabled physicists to isolate and work with single atoms (or ions) held in electromagnetic traps. Lasers are used to cool the ions down to a fraction of a degree above absolute zero and then to probe and manipulate their internal states. This has led to fundamental tests of quantum mechanics and it is hoped that a better understanding of the interaction of radiation with matter will lead to applications in, amongst other things, quantum information processing.

 

Optics and photonics continues to be an area that is both scientifically challenging and a key driver for growth industries such as medicine, telecommunications and consumer electronics. However, these areas cannot continue to thrive unless there are talented, trained scientists and engineers with the education and enthusiasm to develop new ideas and technologies, as well as giving themselves rewarding careers in optics and photonics.

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