Recent Advances in Forward Brillouin Scattering: Sensor Applications.

In-fiber opto-mechanics based on forward Brillouin scattering has received increasing attention because it enables sensing the surrounding of the optical fiber. Optical fiber transverse acoustic resonances are sensitive to both the inner properties of the optical fiber and the external medium. A particularly efficient pump and probe technique-assisted by a fiber grating-can be exploited for the development of point sensors of only a few centimeters in length.

Denaturing for Nanoarchitectonics: Local and Periodic UV-Laser Photodeactivation of Protein Biolayers to Create Functional Patterns for Biosensing.

The nanostructuration of biolayers has become a paradigm for exploiting nanoscopic light-matter phenomena for biosensing, among other biomedical purposes. In this work, we present a photopatterning method to create periodic structures of biomacromolecules based on a local and periodic mild denaturation of protein biolayers mediated by UV-laser irradiation. These nanostructures are constituted by a periodic modulation of the protein activity, so they are free of topographic and compositional changes along the pattern.

Monitoring the Growth of a Microbubble Generated Photothermally onto an Optical Fiber by Means Fabry-Perot Interferometry.

In the present paper, we show the experimental measurement of the growth of a microbubble created on the tip of a single mode optical fiber, in which zinc nanoparticles were photodeposited on its core by using a single laser source to carry out both the generation of the microbubble by photothermal effect and the monitoring of the microbubble diameter. The photodeposition technique, as well as the formation of the microbubble, was carried out by using a single-mode pigtailed laser diode with emission at a wavelength of 658 nm. The microbubble's growth was analyzed in the time domain by the analysis of the Fabry-Perot cavity, whose diameter was calculated with the number of interference fringes visualized in an oscilloscope.

High-speed and high-resolution interrogation of FBG sensors using wavelength-to-time mapping and Gaussian filters.

In this work we report a novel intensity-based technique for simultaneous high-speed and high-resolution interrogation of fiber Bragg grating (FBG) sensors. The method uses a couple of intensity Gaussian filters and the dispersion-induced wavelength-to-time mapping effect. The Bragg wavelength is retrieved by means of the amplitude comparison between the two filtered grating spectrums, which are mapped into a time-domain waveform.

Ytterbium-doped fiber laser as pulsed source of narrowband amplified spontaneous emission.

We report random noise pulsed regime of an ytterbium-doped fiber laser arranged in common Fabry-Perot configuration. We show that the laser output obeys the photon statistics inherent to narrowband amplified spontaneous emission and that the noise pulsing is properly addressed in terms of probability density and autocorrelation functions. Our novel approach reveals, in particular, that the regime's coherence time dramatically shortens, from few ns to tens ps, with increasing laser power.

ASE narrow-band noise pulsing in erbium-doped fiber amplifier and its effect on self-phase modulation.

In this paper, we report a study of the features of polarized and unpolarized narrow-band amplified spontaneous emission (ASE) in a low-doped erbium fiber at 976-nm pumping. We demonstrate that ASE noise can be treated as a train of Gaussian-like pulses with random magnitudes, widths, and inter-pulse intervals. ASE noise can also provide a statistical analysis of these three parameters.

Sensitivity optimization with cladding-etched long period fiber gratings at the dispersion turning point.

This work presents a refractive index sensor based on a long period fiber grating (LPFG) made in a reduced cladding fiber whose low order cladding modes have the turning point at large wavelengths. The combination of these parameters results in an improved sensitivity of 8734 nm/refractive index unit (RIU) for the LP mode in the 1400-1650 wavelength range. This value is similar to that obtained with thin-film coated LPFGs, which permits to avoid the coating deposition step.

Randomized clinical trial of the efficacy and safety of insulin glargine vs. NPH insulin as basal insulin for the treatment of glucocorticoid induced hyperglycemia using continuous glucose monitoring in hospitalized patients with type 2 diabetes and respiratory disease.

Aims: To investigate the clinical efficacy and safety of insulin glargine compared with NPH insulin as basal insulin for the management of corticosteroid-induced hyperglycemia in hospitalized people with type 2 diabetes (T2DM) and respiratory disease.

Materials And Methods: Randomized, two-arm parallel group, clinical trial undertaken from February 2011 to November 2012 on the pneumology ward of the Hospital Regional Universitario de Málaga (Spain), involving 53 participants with T2DM treated with medium/high doses of intermediate-acting corticosteroids. Participants were randomly assigned to receive one single dose of insulin glargine or NPH insulin in three equally divided doses before each meal as basal insulin within a basal-bolus insulin protocol.

A refractive index sensor based on the resonant coupling to cladding modes in a fiber loop.

We report an easy-to-build, compact, and low-cost optical fiber refractive index sensor. It consists of a single fiber loop whose transmission spectra exhibit a series of notches produced by the resonant coupling between the fundamental mode and the cladding modes in a uniformly bent fiber. The wavelength of the notches, distributed in a wavelength span from 1,400 to 1,700 nm, can be tuned by adjusting the diameter of the fiber loop and are sensitive to refractive index changes of the external medium.

Smart Q-switching for single-pulse generation in an erbium-doped fiber laser.

In this paper, we report an active Q-switching of an erbium-doped fiber laser with special modulation functions and novel laser geometry. We experimentally demonstrate that using such a smart Q-switch approach, Q-switch ripple-free pulses with Gaussian-like shape and 17.3 ns width can be easily obtained.

Stenosis in laparoscopic gastric bypass: management by endoscopic dilation without fluoroscopic guidance.

Objectives: gastric bypass is the surgical procedure that is carried out most frequently in the treatment of morbid obesity. Stenosis of the gastro-jejunal anastomosis is a relatively frequent complication that requires endoscopic management. However, the optimal dilation technique is yet to be determined.

Electrically tunable photonic true-time-delay line.

We present a new application of the acousto-optic superlattice modulation of a fiber Bragg grating based on the dynamic phase and group delay properties of this fiber-optic component. We demonstrate a tunable photonic true-time-delay line based on the group delay change of the light reflected from the grating sidebands. The delay is electrically tuned by adjusting the voltage applied to a piezoelectric transducer that generates the acoustic wave propagating along the grating.

Doubly active Q switching and mode locking of an all-fiber laser.

Simultaneous and independent active Q switching and active mode locking of an erbium-doped fiber laser is demonstrated using all-fiber modulation techniques. A magnetostrictive rod attached to the output fiber Bragg grating modulates the Q factor of the Fabry-Perot cavity, whereas active mode locking is achieved by amplitude modulation with a Bragg-grating-based acousto-optic device. Fully modulated Q-switched mode-locked trains of optical pulses were obtained for a wide range of pump powers and repetition rates.

Effective length of short Fabry-Perot cavity formed by uniform fiber Bragg gratings.

In this paper, we describe the properties of Fabry-Perot fiber cavity formed by two fiber Bragg gratings in terms of the grating effective length. We show that the grating effective length is determined by the group delay of the grating, which depends on its diffraction efficiency and physical length. We present a simple analytical formula for calculation of the effective length of the uniform fiber Bragg grating and the frequency separation between consecutive resonances of a Fabry-Perot cavity.

Temperature sensor based on the power reflected by a Bragg grating in a tapered fiber.

We present a temperature sensor based on two chirped gratings made in optical fibers tapered by fusion. One of the gratings has a metallic shielding and acts as sensor element, whereas the second grating provides a reference signal. The sensor is interrogated by measuring the power reflected by the two gratings, and the system has an accuracy of 0.

Simple high-resolution wavelength monitor based on a fiber Bragg grating.

A compact and low-cost device for monitoring the peak wavelength of single-peak spectral distributions is presented. The system is based on the transmission properties of a fiber Bragg grating when its period is modulated. Different types of optical signal, such as the emission of distributed-feedback lasers and the reflection of a broadband optical source produced by fiber gratings used in sensor systems, can be measured with this device.