Optical fibers are ubiquitous, finding wide-reaching applications that enable the modern world. Most importantly, their remarkably low loss has facilitated long-distance telecommunications. Indeed, in late 2017, Corning (as but one of a few large fiber manufacturers) celebrated the delivery of its 1 billionth kilometer of optical fiber, nearly the distance from the Earth to Saturn. Every cell phone conversation or text message propagates along a fiber at some point in its journey. Optical fibers are doped with additives making them attractive active gain media for high power lasers, a market (fiber-based lasers, or fiber lasers) expected to surpass $4 billion by 2025. They are used in imaging systems as endoscopes and as laser power delivery conduits for dental and medical procedures. They are used as the active sensors in sensing systems, enabling the remote and distributed measurement of undersea weather, structural health, and temperature, to name just a few.
Fibers’ performance, however, has reached a sort of plateau, with limitations typically deriving from a bouquet of deleterious nonlinear light-matter interactions between the lightwave and the glass. These usually take the form of a maximum allowable optical power (or rather intensity), either that can be propagated through or produced from an optical fiber. This has inspired a new thrust in specialty fiber design that is largely rooted in conventional wave propagation methodologies. Unfortunately, the vast majority of these waveguide designs offer only incremental improvements to the systems utilizing them since they only enable very slight increases in the maximum allowable power. Consider, for instance, a Poisson-dominated, shot-noise-limited sensing system based on a fiber laser, operating at, or near to, its nonlinearity-restricted upper power limit. Should there be a requirement of a 10 dB enhancement in system signal-to-noise ratio (SNR), this would then require a 20 dB (or 100×) increase in laser power/pulse energy to be realized. Such technological leaps are not possible with the current state-of-the art in waveguide design.
My research and design methodology of optical fibers relies heavily on a highly interdisciplinary approach that marries waveguide engineering and materials science. We owe many of the amazing capabilities of optical fiber to the pioneering work of materials scientists, whose efforts resulted in the mass-production of the low-loss optical fibers which connect our modern world. Soon after the development of the first low loss fiber in the 1970’s, waveguide designers were inspired to develop a wide range of fiber structures that enhance the capabilities of fiber-based systems. Well-known examples include dispersion shifted and tailored fibers, polarization maintaining fibers, and ‘holey’ (or micro- and nano-structured) fibers, to name a few. As such, optical waveguide design (predominantly utilizing silica as the material medium) has traditionally driven most, but not all, advancement in the field of optical fiber technology, with the materials science aspects becoming largely relegated to small niche applications. Today, this practice continues, and hence fiber and fiber laser development now advances only incrementally.
It is precisely this apparent technological stagnation that has inspired my team and I to recognize that materials science can help solve many of the challenges and limitations which waveguide design alone could not. Once we recognized that the aforementioned deleterious phenomena in optical fiber systems relate to a controllable material constant or coefficient, many of which can take on zero- or near-zero-values, it became clear that the performance limiters can be removed simply by prohibiting the unwanted interaction from ever taking place. In short, we have learned how to design these materials systems to achieve optical performance never before seen from optical fibers. This is accomplished through the zeroing or minimization of the material constants that drive the unwanted deleterious processes.
Our current research brings materials science back into the mainstream of fiber design by engineering fibers that that have the potential for disruptive influence. Only by coupling materials science and engineering with electromagnetics will optical fiber capabilities sharply improve in the next decade. This will enable the incredible potential of optical fiber based systems, some of which I am actively pursuing: spectroscopic and coherent lidar systems, high power fiber laser technologies, and communications systems. Our work has also led to designer fibers with unique thermo-mechanical responses that give rise to new distributed sensing architectures. It is important to note that our work also extends other material systems, including crystalline, for next generation applications that rely heavily on these nonlinear processes, such as integrated optical and photonic circuits. The emerging technological renaissance in fibers systems is manifested in my publications and patents.
Three specific examples of current multidisciplinary projects include:
1) Hypersonic acoustic wave engineering of glass optical fiber
2) Bridging a gap between next generation laser sources and active sensing systems such as LIDAR
3) Designing glasses and optical materials for novel optical fiber and waveguide applications including distributed sensing
- Coherent optics/imaging
- Lasers and optical physics
- Modeling and simulation of laser systems
- Optical communications
- Photonic crystals
- Photonic integrated circuits (PICs)
- Radar and LIDAR
- Radio and optical wave propagation
- Remote Sensing
- Semiconductor lasers and photonic devices
- Electronics, Plasmonics, and Photonics
- Photonics: optical engineering and systems
- Sensing systems
Selected Articles in Journals
- Editor’s Pick Paper. M. Tuggle, C. Kucera, T. Hawkins, D. Sligh, A.F.J. Runge, A.C. Peacock, P. Dragic, and J. Ballato, “Highly nonlinear yttrium-aluminosilicate optical fiber with high intrinsic stimulated Brillouin scattering threshold,” Optics Letters, vol. 42, no. 23, pp. 4849-4852 (2017),
- Invited Paper. Cover Article. J. Ballato and P. Dragic, “Glass: The Carrier of Light – A Brief History of Optical Fiber,” International Journal of Applied Glass Science, vol. 7, no. 4, pp. 413-422 (2016).
- P.D. Dragic, C. Ryan, C.J. Kucera, M. Cavillon, M. Tuggle, M. Jones, T.W. Hawkins, A.D. Yablon, R. Stolen, and J. Ballato, “Single- and few-moded lithium aluminosilicate optical fiber for athermal Brilloiuin strain sensing,” Optics Letters, vol. 40, no. 21, pp. 5030 – 5033 (2015).
- J. Ballato and P. Dragic, Invited Paper, "Rethinking optical Fiber: New Demands, Old Glasses," Journal of the American Ceramic Society, vol. 96, no. 9, pp. 2675 - 2692, 2013.
- P.D. Dragic, P. Foy, T. Hawkins, S. Morris, and J. Ballato, “Sapphire-derived all-glass optical fibers,” Nature Photonics, Vol. 6, pp. 629 – 635, 2012.
- C.G. Carlson, P.D. Dragic, R.K. Price, J.J. Coleman, and G.R. Swenson, Invited Paper, “A narrow-linewidth, Yb fiber-amplifier-based upper atmospheric Doppler temperature lidar,” IEEE Journal of Selected Topics in Quantum Electronics, vol. 15, no. 2, pp. 451 – 461, March/April 2009.
- ECE 329 - Fields and Waves I
- ECE 350 - Fields and Waves II
- ECE 465 - Optical Communications Systems
- ECE 466 - Optical Communications Lab
- ECE 495 - Photonic Device Laboratory
- ENG 198 - Special Topics
- ENG 298 - Special Topics
- ENG 491 - Cubesat 1
- ENG 491 - Cubesat 2
- ENG 491 - Nanosatellite Design Build 1
- ENG 491 - Nanosatellite Design Build 2
- ENG 498 - User-Oriented Collaborative De