  A Monte Carlo simulation has been performed to track light rays in
cylindrical fibres by ray optics. The trapping efficiencies for skew and
meridional rays in active fibres and distributions of characteristic quantities
for all trapped light rays have been calculated. The simulation provides new
results for curved fibres, where the analytical expressions are too complex to
be solved. The light losses due to sharp bending of fibres are presented as a
function of the ratio of curvature to fibre radius and bending angle. It is
shown that a radius of curvature to fibre radius ratio of greater than 65
results in a loss of less than 10% with the loss occuring in the initial stage
of the bend (at bending angles Phi circa pi/8 rad).
