Optical Fibers for Biophotonics Applications

Abstract

Major challenges in biophotonics applications to the life sciences include how to collect emitted low-power light (down to the nW range) from a tissue specimen and transmit it to a photon detector, how to deliver a wide range of optical power levels to a tissue area or section during different categories of therapeutic healthcare sessions, and how to access a diagnostic or treatment area within a living being with an optical detection probe or a radiant energy source in the least invasive manner. The unique physical and light-transmission properties of optical fibers enable them to help resolve such implementation issues. This chapter provides the background that is necessary to understand how optical fibers function and describes various categories of fibers that are commercially available for use in biophotonics. The optical power levels that have to be detected or transmitted in a biophotonics process can vary by ten orders of magnitude depending on the particular application. The detected light levels of interest can be in the nanowatt range for spec-troscopic applications, whereas optical power being delivered to a biological specimen can be as high as several watts during light therapy sessions or during laser surgery. Major challenges in biophotonics applications to the life sciences include how to collect emitted low-power light (down to the nW range) from a tissue specimen and transmit it to a photon detector, how to deliver a wide range of optical power levels to a tissue area or section during different categories of therapeutic healthcare sessions, and how to access a diagnostic or treatment area within a living being with an optical detection probe or a radiant energy source in the least invasive manner. Depending on the application, all three of these factors may need to be addressed at the same time. The unique physical and light-transmission properties of optical fibers enable them to help resolve such implementation issues [1-6]. Consequently, various types of optical fibers are finding widespread use in biophotonics instrumentation for life sciences related clinical and research applications. Each optical fiber structure has certain advantages and limitations for specific uses in different spectral bands that