Sapphire fibers grown using the Saphikon EFG technique have proven to be effective delivery systems for Erbium:YAG and Erbium:YSGG laser energy. A special emphasis has been given to the hard tissue dental application following the FDA approval of this procedure in May of 1997. A range of sensor applications also utilize these EFG sapphire fibers. Through the latter half of 1997, Saphikon has successfully transitioned the process from a research/pilot scale level to high volume production. Fiber losses as low as 0.2 dB/meter with an average of 1.5 dB/meter, which were first demonstrated on a research level in which tens of meters were produced, have now been sustained over thousands of meters in full scale production. Use of sapphire fibers in non-medical applications, erbium laser dentistry, and other medical procedures is discussed.
Sapphire fibers grown using the Saphikon EFGTM technique have proven to be effective delivery systems for Erbium:YAG and Erbium:YSGG laser energy. Improvements to the growth process have decreased average fiber attenuation to 1.5 dB/meter with 0.2 dB/meter demonstrated. Diameter control has also improved considerably. Current growth capabilities include diameters ranging from 150 microns to 1500 microns, multiple strands grown simultaneously, and increased length of grown fibers. Laser damage threshold levels of 1250 J/cm2 and power handling capacity of over 11 watts have been demonstrated, as have pulse lifetimes of 150,000 pulses at 275 mJ/pulse output energy. Use of sapphire fibers for high power applications such as dentistry along with other, non-medical applications is discussed.
Utilization of the promising Erbium:YAG laser has been hindered by the lack of a truly effective optical fiber delivery system. In a National Eye Institute funded Phase I SBIR, sapphire fibers produced by the Saphikon Edge-defined, Film-fed Growth (EFGTM) technique were proven effective in delivering 2.94 micron Er:YAG laser energy in pre-clinical in-vitro ophthalmic procedures. A brief overview of the results of both the ab-externo sclerostomy and laser trabecular ablation procedures is given. A Design of Experiments methodology was used to significantly reduce average loss and variability of the EFG fibers, with losses below 1 dB/meter demonstrated in multi-meter lengths of 300 micron diameter fiber. Laser damage threshold levels above 1000 J/cm2, and power handling capability over 8 watts has been demonstrated. Details of ongoing and planned pre-clinical and clinical studies in ophthalmic, otologic, and dental procedures are discussed, along with other, non- medical applications for the sapphire fibers. Introduction of additional fiber diameters and devices is also reviewed.
Single-crystal sapphire fibers are produced by the Saphikon edge-defined, film-fed growth (EFGTM) technique. Total losses below 3 dB/meter have been measured at the Erbium:YAG laser wavelength of 2.94 microns. Fibers with lengths greater than a meter have delivered over 400 mJ of Er:YAG laser energy. EFG fibers have been shown to lose less than 10% transmission when bent to a 6 cm radius. The apparent numerical aperture (NA) has been measured as 0.31 for an unclad fiber, and 0.38 for fiber clad with teflon FEP. Scattering losses were shown to dominate loss, with measurements at both visible and 3 micron wavelengths using integrating spheres. Spectroscopy was used to identify absorptive losses in the EFG fibers.
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