Title :
Tightly focused beam propagation in the waist region
Author_Institution :
Dept. of Transp. Commun., Ukranian State Acad. of Railway Transp., Kharkov, Ukraine
Abstract :
By simulation of focusing using the rigorous solution in 2D-case it is shown that the second spatial moment of intensity distribution does not characterize propagation at the waist region if the waist diameter is close to the wavelength. The effectiveness of beam-fiber coupling is defined by the size of focal spot and depth of focusing. Increasing of the numerical aperture for typical model beam does not proportionally decrease the width of the focal spot but increase the magnitude and weight of sidelobes and probability of aberrations that dramatically decrease efficiency of coupling. The on-axis intensity is found to be proportional to the sinus of divergence angle calculated as generalized value.
Keywords :
aberrations; laser beams; light propagation; optical fibre couplers; optical focusing; aberrations; beam propagation; beam-fiber coupling; focal spot size; focusing depth; intensity distribution; numerical aperture; second spatial moment; tightly focusing; waist diameter; Apertures; Fiber lasers; Laser beams; Lenses; Materials processing; Maxwell equations; Optical coupling; Optical fiber communication; Optical propagation; Rail transportation;
Conference_Titel :
Advanced Optoelectronics and Lasers, 2003. Proceedings of CAOL 2003. First International Conference on
Print_ISBN :
0-7803-7948-9
DOI :
10.1109/CAOL.2003.1250563
