In this work, we show that the enhanced backscatter originating from the recently discovered ROGUE (Random Optical Grating by Ultraviolet or ultrafast laser Exposure) increases the performance of random distributed feedback lasers. The inscription of ROGUEs inside regular optical fibers leads to lower power thresholds, and more compact lasers requiring shorter lengths to achieve lasing. These ROGUEs can also be used in half-open cavities, to further decrease the lasing threshold.
We investigate the properties of the ROGUE (Random Optical Grating by Ultraviolet or ultrafast laser Exposure), a type of grating we demonstrated recently, to better understand the origins of its enhanced reflectivity and broad bandwidth. Through this study, we are able to distinguish which proportion of the signal comes from random defects originating from the laser exposure, and which proportion comes from the random grating written in the fiber core. Through the understanding of the cause and the parameters responsible for the signal enhancement, we can optimize ROGUE fabrication to minimize scattering losses due to the random generation of defects and optimize the signal backscatter. Additionally, we investigate the origins of the ROGUE’s large bandwidth, and derive the parameters defining it allowing us to tune the bandwidth to the optimal value for sensing applications.
Femtosecond laser written devices inside a smartphone screen, in this case Gorilla Glass ®, have been recently demonstrated1 with a high potential of increasing the functionality of cellphones, consuming minimal space using the glass screen2. Even though low loss waveguides have been reported in this glass, the behavior of the refractive index of the glass subject to femtosecond laser radiation is not well understood. Here, we propose a study of that behavior by presenting the identification of two major transitions where the induced refractive index seems to decrease. The first transition occurs at lower fluence and is characterized by a single structure while the second one occurs at much higher fluences, and is well characterized by a double shell structure. In both these transitions, the refractive index at the center of the structure seems to decrease. However, it should be noted that between these two regimes, there is narrow regime in which light seem to be guide in the middle of the fs processed region, confirming the possibility of making a single pass waveguide. The fluence limits of each regime has been investigated as has the quality of the waveguide made by a single and multi-passes. The refractive index of the affected zones is mapped by a highly sensitive phase-interference technique.
 Lapointe, J., Gagné, M., Li M.J., and Kashyap R., "Making smart phones smarter with photonics," Op. Exp., Vol. 22, No. 13, pp. 15473-15483, (2014)
 Lapointe, J., Parent, F., Soares de Lima Filho, E., Loranger, S., and Kashyap R. "Toward the integration of optical sensors in smartphone screens using femtosecond laser writing," Optics Letters, Vol. 40, No. 23, pp. 5654-5657, (2015)