IR-Transmitting Fibers for Biomedical Applications

(WE-Wrk-2-04)

I. D. Aggarwal, L. E. Busse, J. S. Sanghera, L. B. Shaw and D.Talley (1); D. Jansen and N. Tolk (2); A. Cricenti (3); G. M. Peavy (4)  

(1) Naval Research Laboratory, Code 5606, Washington, DC; (2) Vanderbilt University, Dept. of Biomedical Engineering, Nashville, TN; (3) Instituto di Struttura della Materia, Roma, Italy; (4) Beckman Laser Institute and Medical Clinic, University of CA, Irvine, CA

IR-transmitting fibers of selenide- and sulfide-based compositions are being developed at NRL for various biomedical applications.  The fibers have been utilized for FEL applications involving laser surgery and scanning near field microscopy.  We have also fabricated evanescent fiber probes and obtained preliminary IR spectroscopic results for cancerous and non-cancerous tissue.

            Using the Vanderbilt FEL, we have succeeded in delivering output of about 18 mJ at 6.1 $\mu$m from sulfide fiber and about 14 mJ at 6.5 $\mu$m from selenide fiber.  Such power levels are sufficient for soft tissue surgery and are approaching that necessary for bone surgery (i.e., $\tilde{\hspace{0.4em}}$20-30 mJ delivered).

We have successfully fabricated infrared fiber microtips to achieve the first high resolution infrared spectroscopic data, as well as topographical results.  A reproducible and time-efficient chemical etching method was developed for making sub-micron tips on chalcogenide fiber ends, followed by a deposition of metallic gold coating on the tip.  These microtips were tested in the 2.0 to 7.5 $\mu$m wavelength region using the Vanderbilt FEL with a Scanning Near Field Microscope, in collaboration with scientists at Vanderbilt and from the Instituto di Struttura della Materia (Rome).  We achieved record optical resolution in the infrared of 100 nm, and topographical resolution of 25 nm utilizing these microtips with pancreatic cells, bacterial growth medium and an integrated circuit chip.