| 摘要 |
A high power density light delivery device is presented that uses an optical fiber with a diffuser attached at a distal end for use in, for example, photodynamic therapy (PDT) and laser induced thermotherapy (LITT). Uniform scattering in the diffuser section is obtained by either inducing differences in refractive index profiles of the core or in the core-cladding interface with the use of scattering centers or nano-voids. Nano-voids are created in the core or core-cladding interface by focusing high power laser energy or picosecond/femtosecond laser pulses on the quartz fiber material to induce defects. A special method is used that writes defects into or near to the core/cladding boundary through the jacket, without the necessity to first remove the jacket and then recoat the fiber. The method uses a wavelength that is highly transmissive in the jacket and fiber but absorbed in the fiber at very short laser pulses with high peak power. These processes allow the use of high power laser energy and the emission of the resulting high power densities in quartz fibers. The disclosed optical fiber delivery system is suitable for high power applications that require optical fibers with high flexibility and strength and core diameters from about 50 to about 400 microns.
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