Varnham, M.P., Poole, S.B. and Payne, D.N.
A new technique for the measurement of axial-stress in optical-fibre preforms
At Symposium on Optical Fiber Measurements, United States.
02 - 03 Oct 1984.
Full text not available from this repository.
The ability to measure the axial stress in optical-fibre preforms is essential for the development of highly-birefringent specialist fibres, in which high levels of thermal stress are deliberately introduced to modify the fibre propagation characteristics. Conversely, it has been found that the loss of telecommunications-grade fibre can be reduced by minimising the stresses within the core. To date, axial stress profiles have been measured by the rather cumbersome method of reconstruction from the retardation profiles measured transversely across the preform this technique has not seen widespread routine use, presumably because the results rarely justify the complexity of the measurement. In this paper we present a new method for measuring the axial stress profile which should see widespread adoption as a result of its simplicity and convenience. The method has the advantage that it uses the same hardware and software that are commonly used in transverse refractive-index profiling and it is therefore readily incorporated into existing equipment. The technique can also in principle be applied to two-dimensional stress profiling of asymmetric preforms. In addition, the work provides a new insight into how thermal stresses affect fibre refractive-index profiling techniques.
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