Optical fiber-based sensing technology has been rapidly developed and widely used in biological and biomedical studies introducing optical fibers and fiber-optical components into conventional imaging systems. Excitation laser beams can be delivered deep into a targeted biological sample through an optical fiber, which otherwise is subject to strong scattering and absorption by biological tissues. In addition, bulk optics and laser sources can be placed remotely from the test sample. However, the physical limitations of conventional optical fibers lead to a number of disadvantages. Generally, there is a tradeoff between optimal excitation and optimal collection with a single-mode fiber versus a multi-mode fiber. For example, single-mode fibers create higher laser peak intensity at the fiber exit tip, which increases the nonlinear optical excitation rate. However, the lower numerical aperture of single-mode fibers suggests that multi-mode fibers have superior collection efficiency of optical signals such as fluorescence. Accordingly, there exists a need to provide an optimized optical fiber to overcome these obstacles.
Researchers at the University of Michigan have developed an enhanced fiber-optic sensing technique using a dual-core fiber. The smaller, second core is generally coaxially disposed within the first core and has the capability to deliver pulsed laser energy for nonlinear optical excitation of the test sample. The feedback signals can then be collected in both the first core and second core for improved detection efficiency relative to both conventional single-mode and multi-mode fibers.
Applications and Advantages
- In vivo biosensing and imaging
- Monitoring environmental and chemical changes
- Improved detection efficiency relative to conventional single-mode and multi-mode fibers