Single-mode optical fibers in the visible range

The fabrication and characterization of single-mode optical fibers in the visible range are discussed. The small core size is obtained by etching the core layers with a flux of freon during the collapse of the preform. The modifications of the index profile are attributed to diffusion of germanium and to incorporation of freon during collapse. From the index profile, the authors have calculated the cutoff frequencies of the LP/sub 01/ and LP/sub 11/ modes by assuming a Chebyshev power series of the modal field. The results are in good agreement with theoretical previsions as well as the cutoff wavelength and the losses values.<
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