A simple and practical all-fiber approach for realizing ultrafast optical differentiators is proposed and numerically tested. In particular, it is demonstrated that first-order and second-order temporal differentiation of an arbitrary optical waveform can be realized by simply propagating the waveform through a suitable uniform longperiod grating photoinscribed in the core of an optical fiber (...

Critical buildings such as hospitals and police stations must remain functional immediately following a major earthquake event. Due to earthquake effects, they often experience large strains, leading to progressive collapses. Therefore, monitoring and assessing the large strain condition of critical buildings is of paramount importance to post-earthquake responses and evacuations in earthquake-...

We suggest a fiber micro-knot fabricated on a long-period fiber grating. The long-period fiber grating excites high-order modes into the micro-knot and transfers the output back to the Gaussian mode. We show theoretically and experimentally that these micro-knots have an improved Q-factor, higher stability, and have an increased evanescence wave coupling to the environment than single mode fibe...

the deep internal structure of the crust can be determined using appropriate seismic and electromagnetic methods. the natural source magnetotelluric (mt) method is the most suitable electromagnetic technique for probing into the deep crust. a long period magnetotelluric data set obtained in the southern chilean andes is investigated in this paper. dimensionality analysis shows that the data may...

This paper presents the research made at the Laboratory of Optics, Lasers and Systems (LOLS) of the Faculty of Sciences of University of Lisbon, Portugal, in the field of fiber-based sensors. Three areas are considered: sensor encapsulation for natural aqueous environments, refractive index modulation and laser micropatterning. We present the main conclusions on the issues and parameters to tak...