Search

Adolescents typically sleep too little and feel drowsy during morning classes. We assessed whether early morning use of an LED bright light device could increase alertness in school students. Twenty-six (8M/18F) healthy, unmedicated participants, ages 13-18 years, (mean 17.1±1.4) were recruited following screenings to exclude psychopathology. Baseline assessments were made of actigraph-assessed sleep, attention, math solving ability, electroencephalography and structural and functional MRI (N=10-11, pre-post). Participants nonrandomly received 3-4 weeks of bright light therapy (LiteBook Edge™) for 30 minutes each morning and used blue light blocking glasses for 2 hours before bedtime. LiteBooks™ were modified to surreptitiously record degree of use so that the hypothesis tested was whether there was a significant relationship between degree of use and outcome. LiteBooks™ were used 57±18% (range 23%–90%) of recommended time. There was a significant association between degree of use and: (1) increased beta spectral power in frontal EEG leads (primary measure); (2) greater post-test improvement in math performance and reduction in errors of omission on attention test; (3) earlier rise times on non-school days and reduced day-to-day variability in rise times; (4) increased dentate gyrus volume and (5) enhanced frontal connectivity with temporal, occipital and cerebellar regions during Go/No-Go task performance. Degree of bright light therapy use was associated with improvement in sleep cycle consistency, arousal, attention and functional connectivity, but not sleep onset or duration (primary measures). Although this was an open study, it suggests that use of bright morning light and blue light blocking glasses before bed may benefit adolescents experiencing daytime sleepiness.

The 300 kV DC high voltage photogun at Jefferson Lab was redesigned to deliver electron beams with a much higher bunch charge and improved beam properties. The original design provided only a modest longitudinal electric field ( E z) at the photocathode, which limited the achievable extracted bunch charge. To reach the bunch charge goal of approximately few nC with 75 ps full-width at half-maximum Gaussian laser pulse width, the existing DC high voltage photogun electrodes and anode–cathode gap were modified to increase E z at the photocathode. In addition, the anode aperture was spatially shifted with respect to the beamline longitudinal axis to minimize the beam deflection introduced by the non-symmetric nature of the inverted insulator photogun design. We present the electrostatic design of the original photogun and the modified photogun and beam dynamics simulations that predict vastly improved performance. We also quantify the impact of the photocathode recess on beam quality, where recess describes the actual location of the photocathode inside the photogun cathode electrode relative to the intended location. A photocathode unintentionally recessed/misplaced by sub-millimeter distance can significantly impact the downstream beam size.

In this work, the experimental study of spectral broadening due to stimulated Raman scattering with respect to variation of input power of pulsed laser, as well as a 4 m length high-numerical aperture fiber with 100 and 500 m of non-zero dispersion-shifted fiber is reported. The results showed extreme broadening of spectrum which is known as supercontinuum generation, originated by self-phase modulation, four- wave mixing and dominated by cascaded stimulated Raman scattering. Supercontinuum spectrum achieved by total width of 850 nm and a remarkable flatness in the range of 1500 to 1600 nm. Furthermore, output spectrum showed a total of five Stokes waves. Numerical results are also presented.

We report a refractive index tip fiber optic sensor based on a modal interferometer coated with a thin copper film. This device can be used for solute concentration in aqueous mixture measurement. The copper film increases the device reflectivity and, as a result, increases the multimodal interference pattern visibility. To validate the sensor device, different water-glycerol weight concentrations were used in the range from 0 to 45 Glycerol %. The recorded spectral responses show a redshifting, and a sensitivity of 19 pm / (Glycerol % by weight) from 0 to 18 % and 4.7 pm / (Glycerol % by weight) from 18 to 45 % was achieved. Besides, using a phase analysis we calculated a sensitivity of -15 rad/RIU.

In this paper, we propose a fiber optic system to measure the changes in the RGB composition of light in liquid solutions using a plastic optical fiber (POF) as an intrinsic sensor. The measurement system is composed of a 3 W white light-emitting diode as the light source, a 20 cm long U-shaped POF, and an RGB photodiode array that allows us to detect the changes in the RGB composition of the light propagating through the POF. The U-shaped POF has a length of 5 mm without coating, which remains in contact with the liquid solutions. The tests were performed with different concentrations of a mixture of tequila and water. The results obtained with the RGB photodiode array showed that the system has a resolution of 0.39 % and a color change sensitivity of 0.1, 0.6, and 0.4 8–bits/% of sample for red, green, and blue colors, respectively. These results will allow us to design a low-cost prototype to measure the amount of adulteration in liquids.

In this work we browse an overview of the complex dynamics that arise in the non-stationary modes of operation of partly mode-locked fiber lasers under strict polarization control. Both ring and figure-eight cavities implementing saturable absorber mechanisms that rely on nonlinear polarization rotation were considered. The use of twisted fiber ensures robust operation, whereas precise polarization adjustments allow tailoring the nonlinear switching characteristic in a clear and repeatable manner. The enhanced flexibility of these sources allowed identifying and studying a broad spectrum of peculiar dynamics, in particular by implementing the temporal and spectral mapping techniques. These include the emergence, fusion, splitting, complex evolution and eventual decay of chaotic bunches of radiation, which are also subject to large spectral shifts, ample quasi-periodic instabilities, extreme-intensity events or the creation of solitons, among others, as well as the complex evolution of massively multiple soliton states. Finally, with the help of numerical simulation, several aspects of the physics underlying these puzzling behaviors could be elucidated.

Fredric Schiffer,1,2 Alaptagin Khan,1,2 Kyoko Ohashi,1,2 Laura C Hernandez Garcia,1,2 Carl M Anderson,1,2 Lisa D Nickerson,1,3 Martin H Teicher1,2 1Department of Psychiatry, Harvard Medical School, Boston, MA, USA; 2Developmental Biopsychiatry Research Program, McLean Hospital, Belmont, MA, USA; 3McLean Imaging Center, McLean Hospital, Belmont, MA, USACorrespondence: Fredric Schiffer, Developmental Biopsychiatry Research Program, McLean Hospital, Belmont, MA, USA, Tel +1 617 855 2970, Fax +1 617 855 3712, Email fschiffer@mclean.harvard.eduPurpose: Conventional theories of hemispheric emotional valence (HEV) postulate fixed hemispheric differences in emotional processing. Schiffer’s dual brain psychology proposes that there are prominent individual differences with a substantial subset showing a reversed laterality pattern. He further proposed that hemispheric differences were more akin to differences in personality than in emotional processing. This theory is supported by findings that unilateral treatments, such as transcranial magnetic stimulation, are effective if they accurately target individual differences in laterality. The aim of this paper was to assess if a computer test of hemispheric emotional valence (CTHEV) could effectively identify individual differences in HEV and to ascertain if these individual differences were associated with underlying differences in brain structure and connectivity.Patients and Methods: The CTHEV was administered to 50 (18 male/32 female) right-handed participants, aged 18– 19 years, enrolled in a study assessing the neurobiological effects of childhood maltreatment. Based on a literature review, we determined whether CTHEV correlated with lateralized volumes of the nucleus accumbens, amygdala, hippocampus, and subgenual anterior cingulate as well as volume of the corpus callosum.Results: CTHEV scores correlated with laterality indices of the nucleus accumbens (p = 0.00016), amygdala (p = 0.0138) and hippocampus (p = 0.031). A positive left hemispheric valence was associated with a larger left-sided nucleus accumbens and hippocampus and a smaller left amygdala. We identified four eigenvector network centrality DTI measures that predict CTHEV, most notably the left amygdala, and found that CTHEV results correlated with total and segment-specific corpus callosal volumes.Conclusion: Individual differences in HEV can be readily assessed by computer test and correlate with differences in brain structure and connectivity that could provide a mechanistic understanding. These findings provide further support for a revised understanding of HEV and provide a tool that could be used to guide lateralized brain treatments.Keywords: cerebral laterality, brain structure, personality, Dual-Brain Psychology, corpus callosum

La0.7 Sr0.3 MnO3 (LSMO) nanoparticles have been obtained via solution combustion synthesis (SCS) using urea and glycine as fuels. Also, La0.7 Sr0.27 Ca0.03 MnO3 (LSCMO) nanoparticles have been synthesized through solution combustion using urea as fuel. In this paper, the combustion process was carried out with a fuel to oxidant ratio giving fuel deficient conditions ( $\phi ). The thermal analysis (TGA) indicate that the organic residues from the urea-nitrates gel mixture are eliminated above 600 °C and the post-synthesis heat treatment yields the formation of the desired phase without impurities. The obtained phases were analyzed using X-ray diffraction. The infrared analysis confirms the purity of the samples obtained using urea. However, the sample obtained using glycine confirms the formation of SrCO3. The morphology was analyzed using a FE-SEM microscope, and it was found that the particles present a spherical shape with a mean size of around 45 nm in the selected samples. The samples’ energy dispersive X-ray spectra show that the desired elements (La, Sr, Ca, Mn and O) are present in the nanoparticles. The measured zero field cooled (ZFC) and field cooled (FC) magnetizations were recorded from 4.5 to 380 K at 105 A/m to obtain their blocking and Curie temperatures. Moreover, the hysteresis loops measured at room temperature confirm the superparamagnetic behavior of the elaborated samples. According to the results obtained, these nanoparticles have interesting properties that make them candidates to explore not only for their potential in biomedical applications but also in refrigeration and magnetic storage devices.

This paper presents an axial strain laser sensing setup based on a core-offset Mach-Zehnder interferometer (MZI). The core-offset MZI was implemented by fusion splicing of three segments of single mode fiber and was used as wavelength selective filter and sensing head. The experimental results show that in the strain range from 0 to 333.333 με, the laser wavelength emission shifts linearly from 1554 to 1557 nm, achieving a strain sensitivity of 5.2332 pm µε−1 and an R 2 value of 0. 9988. The laser emission has a linewidth of 20 pm and a single-mode suppression ratio of 45 dB. Furthermore, the fiber laser offers output power stability at room temperature, compactness, and robustness.

The aim of this open study was to delineate domains of benefit and effect size measures to design an appropriately powered randomized control trial to assess the efficacy of Brain Balance

We study numerically supercontinuum generation (SCG) in four different 10-cm-long photonic crystal fibers (PCFs) at 800 nm and ~1060 nm, whose parameters are found in the literature, comparing the performance of noise-like pulses (NLPs) and ultrashort pulses (USPs) as the pump. Averaging hundreds of spectra produced by NLPs from two passively mode-locked fiber lasers (thulium and ytterbium), smooth and uniform curves similar to experimental ones were achieved, requiring low or moderate input peak powers. In contrast, spectra exhibiting poor flatness with strong fluctuations up to 24 dB were obtained when using USPs as the pump.

An experimental study of the interaction between a Mylar® polymer film and a multimode fiber-optic is presented for the simultaneous fiber-optic detection of low-pressure and liquid levels. The junction between the polymer and optical fiber produces an interference spectrum with maximal visibility and free spectral range around 9 dB and 31 nm, respectively. Water pressure, which is controlled by the liquid level, stresses the polymer. As a result, the spectrum wavelength shifts to the blue region, achieving high sensitivities around 2.49 nm/kPa and 24.5 nm/m. The polymeric membrane was analyzed using a finite element model; according to the results, the polymer shows linear stress response. Furthermore, the membrane material is operated below the yielding point. Moreover, the finite analysis provides information about the stress effect over the thickness and the birefringence changes. This sensor exhibits a quadratic polynomial fitting with an adjusted R-squared of 0.9539. The proposed sensing setup offers a cost-effective alternative for liquid level and low-pressure detection.

In the present work, the temporal dynamics of an all-normal-dispersion ytterbium-doped fiber ring laser operating in regimes intermediate between continuous-wave operation and mode locking are studied experimentally. Exploiting the segmented memory data acquisition possibilities of an ultrafast digital oscilloscope and through the use of a specifically developed algorithm, the real-time waveform evolution anchored in absolute time could be retrieved, without relying on a fixed reference carried by the signal itself, which does not exist in these regimes. By controlling the time spacing between the successively acquired frames, several dynamics taking place over different time scales could be evidenced and described. These measurements highlight in particular the evolution cycles of intense localized structures including spikes that emerge, grow, decay, interact and describe peculiar trajectories in phase-space diagrams, whereas their temporal positions evolve, driven in particular by gain dynamics. In spite of their dramatic variability, these structures are found to be enduring features of these regimes. Analysis of these data helps assessing the degree of partial mode locking associated with these dynamics. The time-domain mapping technique optimized using segmented memory data acquisition is shown to be useful to characterize precisely highly dynamical evolutions such as those revealed in this work, which are dominated by structures that present large and complex variations in amplitude, shape and position, and develop over different time scales.

A curvature sensing Ytterbium-doped fiber ring, using a Thin Core Fiber Modal Interferometer (TCFMI) was experimentally demonstrated in this work. The TCFMI was implemented by fusion splicing a segment of a thin-core fiber, with a small core diameter, between two single-mode fiber sections. The proposed TCFMI functioned as a wavelength-selective filter in the fiber ring laser cavity. It was optimized to achieve a Side Mode Suppression Ratio (SMSR) of 35 dB; the laser emission produced a sensor resolution of 0.37 nm. The experimental results also showed a high curvature sensitivity close to −38.26 nm/ $\text{m}^{{-1}}$ from 0 $\text{m}^{{-1}}$ to 0.399 $\text{m}^{{-1}}$ curvature range. Here, the laser sensor exhibited a bandwidth of 16 nm in the 1072 nm to 1056 nm wavelength range. The fiber ring laser is a low-cost alternative for curvature sensing applications.

In recent years, laser radiation has been proposed as a therapy tool in the medical field (laser therapy). This work presents the efficiency of a pulsed fiber optic laser in its interaction with synthetic monosodium urate monohydrate (MSUM) crystals, for the management of inflammatory processes and lesions in tissues, muscles and osteoarticular joints affected by crystalline pathologies. The synthetic monosodium urate crystals were made based on the McCarthy method. Such samples were exposed to the direct radiation of the laser light source, whose characteristics are as follows: wavelength centered at λ = 1058 nm, pulse width of τ = 13 ns, repetition frequency of fR = 210 kHz and peak energy of EP = 55 nJ. This radiation is absorbed by the tissue, which produces a photochemical interaction at the molecular level in the crystalline formations. The exposure times were from 7 to 12 minutes, and the best exposure time was presented in 12 m. As a result, the photochemical interaction of light with crystals could be observed, resulting in a variation in molecular structure. Likewise, a decrease in their concentration was found in order to make uric acid crystals, that are within the joints or tissues affected by crystalline pathologies, more soluble to be eliminated through the urine, and therefore, provide at the same time analgesic and anti-inflammatory action in the affected area.

Soliton pulses with picosecond time duration whose amplitude and temporal distribution is random and their repetition frequency correspond to the fundamental frequency have been generated from NPR mode-locking fiber laser.

In this work we use two light sources in the visible range (supercontinuum and pulsed laser source) for the identification, detection and evaluation of the state of oil, based on the fluorescence spectroscopy technique.

In this paper, the performance of a switchable multi-wavelength Er–Yb-doped fibre ring laser incorporating a comb filter is described. The comb filter was developed by using the double-pass Mach–Zehnder interferometer with a Sagnac interferometer (DMZI–SI) arranged in series, a 10-m-long PANDA-type polarisation-maintaining optical fibre, and polarisation controllers (PCs). The laser output can be switched from 1536 to 1548 nm (C-band) via careful adjustment of the PCs. A side-mode separation ratio, greater than 28 dB, was obtained to facilitate stable single-, double-, quadruple-, and quintuple-wavelength emissions, with spectral power and wavelength fluctuations of 0.47–1.06 dB and 0.01–0.06 nm, respectively. The measurements were performed for 60 min at 25 °C. The proposed comb-filter configuration facilitates the double-clad fibre ring laser to realise switchable multi-wavelength emission. Experimental results reveal that the proposed laser demonstrates high stability and significantly improved performance compared to the existing DMZI–SI filter-based systems. This indicates their potential for use in applications involving optical sensing, communication systems, and microwave generation.

We propose and demonstrate a fibre optic system based on bi-tapered silica fibre that can simultaneously measure strain and fibre curvature. Both modalities on the signal can be extracted with no measurable crosstalk between them. The experimental signal has a pure phase modulation when strain is applied to the tapered fibre optic section of the sensor and the signal shows only intensity modulation when an un-tapered fibre section is bent. High sensitivity is achieved from the experimental results for strain and bending losses and the estimation of measurement errors is 0.2 and 0.1%, respectively. This system offers low-cost, compactness and it can be adapted for structural health monitoring.

We present the use of conventional arc discharge technique for manufacturing an optical fiber Fabry-Perot interferometer using hollow core photonic crystal fiber and conventional single-mode fiber. The interferometric structure is composed by several intrinsic Fabry-Perot cavities, here the excitation of several fiber optic modes generates a high frequency interference reflection spectrum with special properties such as a free spectral range of 0.1 nm and visibility near to 6 dB. Thermal analysis has been conducted to demonstrate a sensing application, hence several modal Fabry-Perot interferometers were immersed in liquid and controlled temperature increments were applied. The thermal variations show a linear phase shifting to a shorter wavelength. The analysis exhibits a sensitivity and resolution of 27pm/°C and 0.7 °C respectively. The proposed fiber structure offers compactness, robustness, low-cost fabrication, simple manufacturing process and remote sensing operation. Moreover, it was demonstrated for real sensor applications: suitable sensitivity, good resolution, and long dynamic range.

Some complex dissipative dynamics associated with the noise-like pulse (NLP) regime of a passively mode-locked erbium-doped fiber laser are studied numerically. By means of a convenient 3D mapping of the spatio-temporal pulse evolution, for properly chosen dispersion parameters, several puzzling dissipative dynamics of NLPs are identified, including the expelling of sub-packets that move away from the main bunch, the sudden extinction of isolated sub-pulses, the collision between different internal fragments travelling at different speeds, the rising of sub-pulses, the formation of complex trajectories by substructures that first move away and then return to the main bunch, and so on. In addition, the emergence of optical rogue waves (ORWs) within NLPs is also demonstrated numerically; to help understand these behaviors evidenced in the time domain, spectral analyzes were also performed that show, among other things, that the spectrum of a NLP is notoriously distorted when it hosts an ORW phenomenon. These numerical results are consistent with previously published experimental results.

We study numerically complex noise-like pulse dynamics in a passively mode-locked erbium-doped fiber laser. Wavelength-dependent gain dynamics is modeled as a combination of a three-level and a four-level system, which approximate the gain behavior in the 1530-nm and 1560-nm regions, respectively. The typical deformation of the erbium gain spectrum as it saturates is properly reproduced by this approach. Several puzzling noise-like pulse dynamics that were recently observed experimentally are qualitatively reproduced numerically, in particular slow quasi-periodic energy variations and the emergence and walkoff of wavelength-shifted radiation components. These results clearly reveal that gain dynamics is deeply involved in the onset of such complex temporal and spectral instabilities in these sources.

In this work, we show an optoelectronic system based on a plastic optical fiber (POF), which can detect changes in the RGB composition in liquid solutions. This system consists of a white light (LED) with 3 W of power, and 20 centimeters of POF with cladding in the U-configuration,where 0.5 cm is without cladding that allows having contact with the rest of the solution. Also, the arrangement of photodiodes allows us to capture the intensity of light that comes from the fiber. Furthermore, we tested different solutions where we observed changes in the RGB color composition, using different concentrations of water with alcohol. These results shall allow us to design in the future a prototype for measuring the refractive index in different liquid solutions.

In this paper a design of a graphical user interface (GUI), to observe polarization states changes on a standard single-mode optical fiber (SMF-28) that has been twisted, is presented. Here, we modify two different groups of parameters: 1) the input polarizationellipticity injected to an optical fiber; this is, the tilt or the angle of propagation and the intensity on each electric field or the shift phase; the other group is 2) the birefringence fiber values, mainly induced by mechanicalefforts, since its fabrication either by pinching, bending or in general by manipulating it; obtaining simulated results that describes the output polarized light at the end of the fiber. The results are depicted on the Poncaire Sphere and Stokes parameters graphics. Moreover, the GUI was developed in Visual-Basic, used for the interface windows, and it was connected to Matlab, used like mathematic engine.

This work reports the experimental demonstration of supercontinuum (SC) generation with broad spectral output of 950 nm maximum or a 3.7 dB variation within the range from 1300 to 1600 nm and demonstrate how some fiber properties enhance nonlinearities and shows different SC output spectrum. Broad spectrum was achieved throughout a subnanosecond microchip pulsed laser operating at 1064 nm. Three different conventional fibers were employed: highnumerical aperture fiber (HNAF), dispersion shifted fiber (DSF) and single mode fiber (SMF). SMF was wrapped in different diameters to induce fiber losses. Several combinations of these three fibers and diameters resulted in high spectral width as well as high flatness in the telecom band.

This paper presents several broad-spectrum sources generated by pumping a 532nm laser microchip, with 600ps pulses and various combinations of conventional thin-core optical fibers. Fibers with a core of 2.1μm, 2.5μm and 3.5μm were used; with lengths of 38m, 23.3m and 19.7m respectively. We present the results derived from experimenting with each type of fiber separately, as well as making combinations among them, obtaining broad spectrum light sources (supercontinuous light) with a spectral width of approximately 300nm and powers greater than -20dBm.

We show a broad-spectrum source by pumping short pulses from 600 ps at 532nm wavelength in two thin-core fiber sections achieving a source with a spectral width of approximately 300 nm.

Mn0.75Zn0.25Fe2O4 nanoparticles were used to characterize magnetic fields using an all-fiber Fabry–Perot interferometer. The 20-nm nanoparticles were fabricated with citrate and displayed a coercive field of approximately 10 mT. The nanoparticles were dispersed in oleic acid to prepare a magnetic fluid to fill a Fabry–Perot structure fabricated by arc splicing with conventional single-mode and hollow core photonic crystal fibers. This device provided sensitivity and resolution of 0.11 dB/mT and 0.09 mT, respectively. Thermal analysis indicated that the magnetic measurements are weakly depending on temperature (0.7 pm/°C and 7 × 10−3 dB/°C). This device offers low-cost fabrication, simple implementation and may be used in several industrial applications.

We used a Fourth-Order Runge-Kutta in the Interaction Picture Method for simulating supercontinuum generation (SCG) in a designed solid-core photonic crystal fiber (PCF) with zero dispersion wavelength (ZDW) at 800 nm and other solid-core PCF with ultra-flattened dispersion in the range of 1300 nm to 1550 nm obtaining a SCG with a bandwidth of 850, 1200, and 2300 nm using a femtosecond laser in the three communication windows. Here we achieved ZDW close to the first, second and third communication windows which gives us the possibility to obtain a wide spectrum at these points with good quality in the 40-dB bandwidth for SCG with flat spectrum. The design of the two PCFs proposed here is analyzed numerically using finite element method (FEM) and we showed the results when we used a pump wavelength in normal and anomalous dispersion regimes close to ZDW points of these two PCFs for SCG.

In this work an optical sensing setup is designed and implemented to estimate the ripening in fruits. Here by white light reflected signal the color fruit can be calculated to provide information about the fruit condition. The main components in the proposed system are red, green and blue (RGB) module, photodetector and an optical plastic fiber. Moreover the sensing system is compact and versatile, due to the light signal used in the system can me adequate according to some fruit requirements by using a Labview interface, besides the detection and result displaying is proposed by a microcontroller device and Matlab interface. In order to demonstrated the system proposed a guava fruit was used to show the evolution color changes during its ripeness.

This paper presents the experimental results obtained in the development of novel optical fiber lasers architectures operating in continuous-wave and pulsed regimes. The first laser shown is an actively Q-switched operating at 1565 nm with a double-clad fiber doped with Er 3+ /Yb 3+ , pulse widths in the order of hundreds of ns, repetition rate from 200 kHz to 310 kHz, and average power up to 2.5 W. The second architecture is a passive mode-locked laser with higher harmonics generation. Output characteristics are; center wavelengths 1563 nm, noise-like pulses with durations around 80 ns, harmonics evolution up to the order 1270, and repetition rates to 259 MHz. The results presented seek to provide a comparison between two types of optical fiber lasers of great technological interest.

We introduce a photochemical alternative procedure for uric-acid crystals degradation by controlled exposure of pulsed near infrared radiation from a ring fiber laser. The laser provides a wide spectrum from 1050 nm to 1120 nm, this spectrum exhibits a burst pulsed response with a pulse packet frequency rate of 210 kHz and an internal pulse frequency of 29 MHz. To demonstrate the technique, uric acid crystals were prepared synthetically and exposed under different radiation conditions, then by using an effective digital image processing the samples are before and after compared. Results confirm it is possible to exponentially reduce the number of crystals by an adequate combination of energy and number of pulses. The technique offers the possibility to reduce up to 50 % of the initial uric acid in a long period of safety wavelength radiation.

In this paper, we proposed a system to integrate optical and electronic instrumentation devices to predict a mode-locking fiber laser response, using a remote data acquisition with processing through an artificial neural network (ANN). The system is made up of an optical spectrum analyzer (OSA), oscilloscope (OSC), polarimeter (PAX), and the data acquisition automation through transmission control protocol/internet protocol (TCP/IP). A graphic user interface (GUI) was developed for automated data acquisition with the purpose to study the operational characteristics and stability at the passively mode-locked fiber laser (figure-eight laser, F8L) output. Moreover, the evolution of the polarization state and the behavior of the pulses are analyzed when polarization is changed by proper control plate adjustments. The data is processed using deep learning techniques, which provide the characteristics of the pulse at the output. Therefore, the parameter classification-identification is in accordance with the input polarization tilt used for the laser optimization.

The analysis of polarization evolution in a tunable fiber laser in a ring configuration is presented, an interferometer was used to tune the laser and was manufactured with thin-core fiber (Thin-Core Fiber, TCF). The interferometer was achieved by splicing a segment of thin-core fiber (Thin-Core Fiber, TCF) between two segments of single-mode fiber SMF-28 (Single-Mode Fiber). Single and double and triple line emissions were obtained by means of the angular micrometric deflection in the TCFMI (Thin-Core Fiber Modal Interferometer) interferometer section, as well as depending on the position of the polarization controller plates (PC1 and PC2). Also, a uniform tuning was achieved, depending on the polarization state of the pumping source and the position of the plates of the second polarization controller (PC2), which started at 1534.70265 nm and moved to the left side to 1531.65142 nm and the evolution of the polarization state in this tuning range was observed. A tuning range of 1527.01738 to 1553.66363 nm was also achieved by means of the angular micrometric deflection in the TCFMI interferometer section.

In this work, we present an analytical methodology to evaluate the response of a three-beam path Mach-Zehnder interferometer (MZI) based on a multiresolution signal analysis using a discrete Wavelet transform (DWT). Here, the MZI was implemented by fusion splicing of a segment of ytterbium-doped double cladding photonic crystal fiber (Yb-d-DCPCF) between two pieces of single mode fibers. Moreover, Yb-d-DCPCF core and claddings were used as the arms of the MZI, while the hole collapsed regions acted as optical fiber couplers. So, the MZI interference pattern occurs of two main modal interferences, between the core and cladding. Hence, as a result, an interference spectrum with aperiodic sinusoidal waveform was observed. In this way, in our proposed methodology we decompose the interference spectrum into eight bands of spatial frequency (SF) using the DWT with a wavelet mother Daubechies order twenty (db20) for detecting the two main modal interferences. The spectral analysis of the decomposed signal reveals that the level 7 and 8 contain the two main modal interference between the core and the cladding 1 and cladding 2, respectively. Additionally, the fundamental mode is obtained in the level 8. In the same way, the decomposed signal provides information about the wavelength and spatial frequency simultaneously that can be used for knowing the energy spectral density. Finally, we claim that the proposed methodology provides the best accuracy in SF of MZI intermodal and DWT indicates the wavelength region in which the propagation modes occur, improving the description of the refractive index difference.

In this work, we focus on the numerical study of a NLP, generated by a figure-eight fiber laser (F8L), propagating in single-mode fiber (SMF-28) and photonic crystal fiber (PCF) through the RK4IP method. We have performed a numerical study in the evolution of supercontinuum spectra by varying the input power of NLP, using even lower input powers than those used with ultrashort pulses. Our main purpose is to highlight the NLPs are an excellent seed for wide, soft and in particular, flattened spectra.