Optical fibre that preserves the properties of light

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A new type of optical fibre that has a large core diameter and preserves the properties of light has been developed by scientists from the Moscow Institute of Physics and Technology (MIPT) and the Russian Academy of Sciences. The results of the study could enable high power pulsed fibre lasers and amplifiers as well as polarisation-sensitive sensors.

When it comes to optical fibre applications, preserving the properties of light is said to be crucial. The researchers claim there are two principal parameters that need to be preserved: the distribution of light intensity and the polarisation of light.

The researchers found that if the expansion of the fibre occurs adiabatically – relatively slowly – it is possible to reduce the amount of energy transferred to other modes – parasitic nonlinear effects which affect the intensity of the optical signals – to less than 1%, even with a large core diameter of up to 100µm.

To preserve the polarisation state of the light, the scientists showed that the geometric length of the path travelled by light through the fibre depends on the fibre core diameter: It decreases as the diameter is increased.

According to the group, the ability to measure this parameter is in itself evidence of the fact that the polarisation state in the fibre is preserved.

"The fibre samples we obtained have demonstrated great results, indicating good prospects for further development of such technological solutions,” said MIPT Professor Sergey Nikitov. “They will find use not only in laser systems but also in optical fibre sensors, where the change of polarisation characteristics is known in advance, since they are determined by external environmental factors, such as temperature, pressure, biological and other impurities.

“Besides, they have a number of advantages over semiconductor sensors. For example, they need no electrical power and can carry out distributed sensing."