Fiber optic nanotechnology: a new frontier of fiber optics

Abstract

Nanophotonics is an exciting new field of nano-science that deals with the interaction of light with matter on a micro/nanometer size scale. It is a field in which photonics merges with nanoscience and nanotechnology, providing challenges for fundamental research and creating opportunities for new technologies and applications. Nanotechnology has spawned new areas of research for fiber optics, namely fiber optic nanophotonics. When we think of optical fibers, we typically think of optical propagation through waveguides of dimensions greater than or similar to the optical wavelength. Conventionally, little attention need be given to sub-wavelength or nano meter size features. However, when nano-features are intentionally incorporated into optical fibers, many interesting phenomena may arise. For example, with nano-features of sufficient refractive index contrast, a properly designed optical fiber can do more than simply guide light from one point to another. Such features can be used to create different types of waveguiding phenomena as well as enabling capabilities for manipulation of light that go beyond conventional optical transport. This additional functionality offers great potential of fiber-based nanotechnology for applications in communications, computation, sensing, biology and chemistry for both waveguides and waveguide-based devices. Nanotechnology can be exploited in multiple ways. In perhaps the most widely recognized form, nano-features provide an additional mechanism for confinement of light in so-called photonic crystal fiber. The concept of using air-glass structures to guide light was proposed in 1974 as a possible design for low-loss optical fiber. However, the field saw little activity until 1996. A major reason for this was because conventional fibers were so successful commercially that most research efforts were focused on exploiting more conventional fibers. Demonstrations of fibers with photonic crystal cladding, and later photonic band-gaps, in the late 1990s reinvigorated the field and attracted new research interest because air-glass microstructures offer a number of interesting physical effects that do not exist in conventional fibers. Microand later nano-structured optical fibers became an extremely active research area while miniaturization pushed toward micro/nanophotonic devices, such as tapers, resonators and interferometer for a wide range of telecommunications and specialty applications.