Lecture 4 - Constructing a laser

From the programme:

How easy is it to assemble a laser? We shall answer this question by reconstructing what Maiman did in 1960 in California, where the laser was first demonstrated. A photographer’s flash tube, along with a good-quality rod of aluminium oxide doped with chromium is one of the key components of the so-called ruby laser. But there are many other types of systems, chemical and physical, which can be induced to ‘lase’. The requirement for ‘lasing action’ – the creation of a ‘population inversion’ of excited states – will be illustrated, and the stimulation of these excited states to give up their energy in the form of light emission demonstrated. Thus laser light emerges from a cavity as a narrow, exceptionally intense and parallel beam which can be put to many uses. There are lasers which operate in the ultra-violet, visible or infrared regions of the spectrum and a few of their properties will be demonstrated. Some lasers can be made to produce ultra-short pulses of light, others extraordinarily ‘pure’ colours. The polarisations of laser light as well as its so-called ‘coherence’ will be illustrated.

We shall focus upon many other types of lasers, including those that operate in the gas phase and describe some of their spectacular properties.






John Meurig Thomas and David Phillips



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