Specialty Fibers for Novel Fiber Lasers and Devices
Designs of novel specialty fibers are finely tuned to enable transmission of light carrying specific properties (wavelength, profile, polarization, dispersion, etc.), opening the route towards potential applications such as average or peak power scaling of fiber laser, beam shaping, optical sensing, and telecommunications.
As the complexity of the fiber inner structure increases, the fabrication process becomes critical. Therefore, there is a strong demand for advanced experimental diagnostics enabling to characterize in detail the transmitted light. Here, a powerful mode analysis technique, directly inspired from the spatially and spectrally resolved imaging experiment (S2 imaging), has been employed to successfully interrogate several specialty fiber prototypes. A few striking examples are presented where targeted applications are proposed according to the measured mode content.
Furthermore, challenges related to the monolithic integration of active specialty fibers with commercially available fiber technologies are highlighted and tackled via two examples of fiber laser systems: one employing an active large-mode photonic crystal fiber and a second using an active seven-core fiber.
Conservation Laws and Optical Interactions at Dielectric Interfaces
Electromagnetic waves carry energy, and linear, and angular momenta that can be exchanged with material systems leading to specific optical phenomena. The light matter interaction governed by the conservation laws can manifest itself as the mechanical action of light at the microscopic level. The electromagnetic force is a consequence of the energy or direct momentum transfer from light to matters. In addition, the coupling between the orbital and spin angular momenta governed by the conservation law of angular momentum is critical for understanding some optical effects and manipulating photon states. These fundamental optical interactions are expected to occur in lower dimensionality systems such as interfaces as well. The spatially varying optical properties and spatial confinement may lead to new and robust capabilities to manipulate physical properties of matter over large scales.
Multimaterial Fibers and Tapers: A Platform for Nonlinear Photonics and Nanotechnology
Chalcogenide glasses (ChGs) exhibit higher optical nonlinearities than rival infrared glasses and have a wider transparency window at MIR. Many researchers previously shied away from ChG fibers due to their large normal dispersion, low damage threshold, and poor mechanical properties. Our approach for MIR-supercontinuum generation (SCG) is based on tapering a novel ChG fiber structure. The nanotapers at the same time are highly nonlinear and mechanically robust; Furthermore, the large core-cladding index contrast enabled us for dispersion engineering. A full experimental and simulation dispersion and nonlinear characterization have been performed on the samples. The nanotapers have been pumped at 1.55 and 2 µm and over an octave spectral-broadening have been achieved.
Our unique tapering capabilities enabled us to observe the Plateau-Raleigh-Instability (PRI) for the first time in a solid fiber during fiber tapering. The PRI can be used for fabricating scalable structured particles with sizes ranging from millimeters to nanometers.
We also discovered that cold-drawing of a polymer fiber or film with a fragile material embedded in or coated on it, causes a mechanical instability manifesting itself in a wave propagating along the fiber or film, resulting in the fragile material undergoing a periodic breakup along the sample length.