The lab-on-chip platform has presented a powerful opportunity to improve functionalization, parallelization, and miniaturization on planar or multilevel geometries that has not been possible with fiber optic technology. A migration of such lab-on-chip devices into the optical fiber platform would therefore open the revolutionary prospect of creating novel lab-in-fiber systems on the basis of an efficient optical transport highway for multifunctional sensing. For the lab-in-fiber, the core optical waveguide inherently offers a facile means to interconnect numerous types of sensing elements along the optical fiber, presenting a radical opportunity for optimizing the packaging and densification of diverse components in convenient geometries beyond that available with conventional lab-on-chips.
In this talk, 3D patterning inside the optical fiber by femtosecond laser writing, together with selective chemical etching, is presented as a powerful tool to form refractive index structures such as optical waveguides and gratings as well as to open buried microfluidic channels and optical resonators inside the flexible and robust glass fiber. I establish cladding waveguides, X-couplers, fiber Bragg gratings, microholes, mirrors, optofluidic resonators, and microfluidic reservoirs that define the building blocks for facile interconnection of inline core-waveguide devices with cladding optofluidics. With these components, more advanced, integrated, and multiplexed fiber microsystems are presented, demonstrating fluorescence detection, Fabry–Perot interferometric refractometry, and simultaneous sensing of refractive index, temperature, and bending strain. Further, optical resonator arrays and wavefront splitting interferometers are explored to deepen fringe contrasts beyond that available with a single Fabry Perot resonator to add the benefits of improved device sensitivity and resolution. The flexible writing technique and multiplexed sensors described here open powerful prospects to migrate the benefits of lab-on-chips into a more flexible and miniature lab-in-fiber platform for highly functional and distributed sensing capabilities.
References:
[1] M. Haque, K. K. C. Lee, S. Ho, L. A. Fernandes, P. R. Herman, “Chemical-assisted femtosecond laser writing of lab-in-fibers”, Lab Chip 14, p. 3817, 2014. http://dx.doi.org/10.1039/C4LC00648H
[2] J. R. Grenier, M. Haque, L. A. Fernandes, K. K. C. Lee, P. R. Herman, “Femtosecond laser inscription of photonic and optofluidic devices in fiber cladding”, in G. Marowsky (ed.), Planar waveguides and other confined geometries, p. 67, Springer Series in Optical Sciences vol. 189, New York, 2015. http://dx.doi.org/10.1007/978-1-4939-1179-0_4
