A reconfigurable dual-passband to single-passband filter, which is based on miniaturized ring resonators, is presented. The filter is designed for 448 MHz and 668 MHz as the central passband frequencies. Simulations are used for enhancing the design. The lower passband can be eliminated by just changing the location of a short. The filter is implemented using microstrip technology on a RO3010 substrate with thickness of 1.28 mm. Measurements for the optional eliminated band are in good agreement with the expected values. The transmission is -3 dB at the central frequency for dual-passband configuration and -26 dB for single-passband configuration.
Erbium Ring Fiber Laser Cavity Based on Tip Modal Interferometer and Its Tunable Multi-Wavelength Response for Refractiv...Published: 10 August 2018 by MDPI in Applied Sciences
A tunable multi-wavelength fiber laser is proposed and demonstrated based on two main elements: an erbium-doped fiber ring cavity and compact intermodal fiber structure. The modal fiber interferometer is fabricated using the cost-effective arc splice technique between conventional single-mode fiber and microfiber. This optical fiber structure acts as a wavelength filter, operated in reflection mode. When the refractive index and temperature variations are applied over the fiber filter, the ring laser cavity provides several quad-wavelength laser spectra. The multi-wavelength spectra are tuned into the C-band with a resolution of 0.05 nm. In addition, the spectra are symmetric with minimal power difference between the lasing modes involved, and the average of the side mode suppression ratio is close to 37 dB. This laser offers low-cost implementation, low wavelength drift, and high power stability, as well as an effect of easy controllability regarding tuned multi-wavelength.
A compact, magnetic field sensor system based on a short, bi-tapered optical fiber (BTOF) span lying on a magnetic tape was designed, fabricated, and characterized. We monitored the transmission spectrum from a broadband light source, which displayed a strong interference signal. After data collection, we applied a phase analysis of the interference optical spectrum. We here report the results on two fabricated, BTOFs with different interference spectrum characteristics; we analyzed the signal based on the interference between a high-order modal component and the core fiber mode. The sensor exhibited a linear response for magnetic field increments, and we achieved a phase sensitivity of around 0.28 rad/mT. The sensing setup presented remote sensing operation and low-cost transducer magnetic material.
A Core-Offset Mach Zehnder Interferometer Based on A Non-Zero Dispersion-Shifted Fiber and Its Torsion Sensing Applicati...Published: 10 June 2016 by MDPI in Sensors
In this paper, an all-fiber Mach-Zehnder interferometer (MZI) based on a non-zero dispersion-shifted fiber (NZ-DSF) is presented. The MZI was implemented by core-offset fusion splicing one section of a NZ-DSF fiber between two pieces of single mode fibers (SMFs). Here, the NZ-DSF core and cladding were used as the arms of the MZI, while the core-offset sections acted as optical fiber couplers. Thus, a MZI interference spectrum with a fringe contrast (FC) of about 20 dB was observed. Moreover, its response spectrum was experimentally characterized to the torsion parameter and a sensitivity of 0.070 nm/° was achieved. Finally, these MZIs can be implemented in a compact size and low cost.
An all in-fiber Mach-Zehnder interferometer using a photonic crystal fiber is presented for a switchable multiwavelength laser, which emits in the L-band for communications. Three laser emissions are achieved by controlling the polarization state.
Ring self-Q-switched Er3+/Yb3+ fiber laser operated at 1565 nm is presented. The configuration has: high efficient (~62%), high output power (10 W) and short pulses generation (ns), allowing a stable multiple pulsing regime.
Analytical Modelling of a Refractive Index Sensor Based on an Intrinsic Micro Fabry-Perot InterferometerPublished: 15 October 2015 by MDPI in Sensors
In this work a refractive index sensor based on a combination of the non-dispersive sensing (NDS) and the Tunable Laser Spectroscopy (TLS) principles is presented. Here, in order to have one reference and one measurement channel a single-beam dual-path configuration is used for implementing the NDS principle. These channels are monitored with a couple of identical optical detectors which are correlated to calculate the overall sensor response, called here the depth of modulation. It is shown that this is useful to minimize drifting errors due to source power variations. Furthermore, a comprehensive analysis of a refractive index sensing setup, based on an intrinsic micro Fabry-Perot Interferometer (FPI) is described. Here, the changes over the FPI pattern as the exit refractive index is varied are analytically modelled by using the characteristic matrix method. Additionally, our simulated results are supported by experimental measurements which are also provided. Finally it is shown that by using this principle a simple refractive index sensor with a resolution in the order of 2.15 × 10−4 RIU can be implemented by using a couple of standard and low cost photodetectors.
This paper presents the design and implementation of an optical sensor to detect color changes in fruit by means of white light reflection to measure fruit ripeness in industrial and agricultural applications. The system consists of a LED RGB array including photodetectors, a power source and plastic optic fiber (POF). By means of Labview ® graphic interface we can control the power emission of the diodes digitally mixing the colors at different intensities until we achieve white light to be used as a source for the color sensor. We used an ATmega2560 microcontroller as a data collection device to monitor the colors obtained and to show them as color models using Matlab ®. We show results from tests conducted using two guava samples, observing the evolution of the color change on the fruit skin until they became overripe. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Fabrication and characterization of a non-zero dispersion-shifted mechanically-induced long-period grating for optical f...Published: 25 August 2015 by SPIE-Intl Soc Optical Eng in Laser Beam Shaping XVI
We present the fabrication and characterization of a mechanically induced long period grating (MLPG) using a grating period of 400 μm and 1m of NZ-DSF. Pressure is gradually applied up to 120 Lb at different angles like 0, 30, 45 and 60 degrees. An attenuation band is observed centered at a wavelength around 1064nm using a fiber position of 30 degrees with respect to the grating´s metal plate and a maximum pressure of 145 Lb. The loss band presents a maximum depth of 22dB and a bandwidth of approximately 10nm. Torsion and curvature characterizations did not change the output spectrum of the optical grating. However, temperature characterization depicted a small shifting which could be insignificant for some applications. Still, there is 16dB attenuation as temperature increases in a range from room temperature up to 450°C. These preliminary studies show that this 1064 nm centered wavelength MILPG might be used in a low linear dynamic range with temperature (75-300)°C as a temperature sensor. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
In this letter, a temperature sensor based on a fiber ring laser is presented. A fiber Bragg grating was used as a sensor head, and a Mach-Zehnder interferometer (MZI) was utilized as a wavelength selective filter to enhance the temperature sensing capability. The MZI was achieved by splicing a piece of photonic crystal fiber between two segments of single-mode fiber. Moreover, it is shown that when the laser emission wavelength is shifted as the temperature is varied, achieving a temperature sensitivity of 18.8 pm/°C at 1550 nm, within the temperature range from 20 °C to 90 °C.
Modified All-Fiber Fabry–Perot Interferometer and Its Refractive Index, Load, and Temperature AnalysesPublished: 01 June 2015 by Institute of Electrical and Electronics Engineers (IEEE) in IEEE Photonics Journal
In this letter, a torsion sensing arrangement based on a three beam path Mach–Zehnder interferometer (MZI) is presented. The MZI with three beam paths was fabricated by fusion splicing a piece of double ytterbium‐doped double‐cladding photonic crystal fiber (Yb‐d‐DPCF) between two segments of single mode fiber (SMF). Moreover, in our sensing arrangement the Yb‐d‐DPCF segment is acting both as the MZI as the gain medium. Here, a spectral MZI fringe shifting is induced by applying torsion over the Yb‐d‐DPCF. By this setup, a torsion sensitivity of 0.001 nm/° was achieved. Finally, it is shown that the sensing arrangement is compact and robust. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1857–1860, 2015
Sub- and Nanosecond Pulsed Lasers Applied to the Generation of Broad Spectrum in Standard and Microstructured Optical Fi...Published: 29 April 2015 by Springer Nature in Springer Series in Optical Sciences
This chapter provides an experimental and theoretical overview of pulsed lasers applications focused on obtaining supercontinuum light source. Particular attention is paid to the supercontinuum generation with short piece of conventional and microstructured fiber. An investigation in the regime of long pulses is performed through pumping sources with pulse duration of 700 ps and 6 ns, showing that it is possible to obtain this kind of source in an economical way by using a microchip laser and a few meters of standard fiber, and achieve spectral broadening comparable with that one using a femtosecond laser. In this chapter the nonlinear effects in short lengths of optical fibers are analyzed, starting with modulation instability, stimulated Raman scattering, and stimulated Brillouin scattering. The interaction of these effects for obtaining supercontinuum light source is shown. It also shown that using a Nd:YAG laser with pulse duration of 6 ns and a repetition rate of 50 Hz to pump two joined photonic crystal fibers with different microstructure and dispersion is possible to obtain a spectral broadening with a greater flatness. Finally the spectral evolution of pumping pulses is presented for different input intensities and different lengths of standard and microstructured fibers.
Generation of stable high order harmonic noise-like pulses in a passively mode-locked double clad fiber ring laserPublished: 04 March 2015 by SPIE-Intl Soc Optical Eng in Fiber Lasers XII: Technology, Systems, and Applications
We study a passively mode-locked double-clad Erbium-Ytterbium fiber ring laser producing noise-like pulse through nonlinear polarization evolution and polarization selection. Single noise-like pulsing is only observed at moderate pump power. As pump power is increased, and through polarization controllers adjustments, harmonic mode-locking of growing order were successively appearing. For pump powers close to the damage threshold of the setup, we reach harmonic orders beyond 1200 and repetition frequencies in excess of a quarter of a GHz. Finally, these experimental results could be useful in the quest for higher pulse energies and higher repetition rates in passively mode-locked fiber lasers. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Analysis of a low-cost technique for the generation of broadband spectra with adjustable spectral width in optical fiber...Published: 27 February 2015 by SPIE-Intl Soc Optical Eng in Nonlinear Frequency Generation and Conversion: Materials, Devices, and Applications XIV
We study the nonlinear processes involved in the generation of broadband spectra with selectable spectral width. The continuum spectra were generated in short piece of SMF-28 fiber as nonlinear media pumped by a microchip laser at 1064 nm. Bending effects in the spectra were observed through wrapping the fibers on a cylindrical tube. We show that the spectral characteristics directly depend on the properties of the nonlinear medium, the excited nonlinear effects, and the location of the wrapped section which can produce a filtering effect on the SC spectrum. Finally, the main advantages of the proposed scheme are to obtain an adjustable bandwidth for a supercontinuum source through an easy and flexible control, and to provide a low-cost configuration in which photonic crystal fibers are not used. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
The implementation of signal filters in a real-time form requires a tradeoff between computation resources and the system performance. Therefore, taking advantage of low lag response and the reduced consumption of resources, in this article, the Recursive Least Square (RLS) algorithm is used to filter a signal acquired from a fiber-optics-based sensor. In particular, a Long-Period Fiber Grating (LPFG) sensor is used to measure the bending movement of a finger. After that, the Gaussian Mixture Model (GMM) technique allows us to classify the corresponding finger position along the motion range. For these measures to help in the development of an autonomous robotic hand, the proposed technique can be straightforwardly implemented on real time platforms such as Field Programmable Gate Array (FPGA) or Digital Signal Processors (DSP). Different angle measurements of the finger's motion are carried out by the prototype and a detailed analysis of the system performance is presented.
In this letter, a highly sensitive curvature sensor arrangement based on an abrupt tapered fiber (ATF) concatenated with an all-fiber micro Fabry-Pérot interferometer (MFPI) is presented. Here, as the ATF is bent, the MFPI spectral fringes contrast decreases. In addition, the curvature sensitivity is considerably enhanced due to the use of the ATF. Finally, it is shown that with this arrangement, at 1530-nm wavelength, it is possible to detect curvature changes with a sensitivity of 11.27 dB/m -1 and a curvature resolution of 8.87 × 10 -3 m -1 within the measurement range of 0 - 3.5 m -1 .
A Mach-Zehnder Interferometer (MZI) using an ytterbium doped photonic crystal fiber (YbDPCF) is presented as a torsion sensor. The MZI was fabricated by fusion splicing an YbDPCF between two single mode fibers (SMF), which spectral interference pattern is modified by applying torsion over the YbDPCF. For this arrangement the torsion sensitivity achieved was 0.001 nm/°. In addition, experimental results of polarization states and the group birefringence value are provided. This approach is compact, portable and inexpensive and it requires a very simple fabrication procedure.
We show the sensing of load by means mechanically induced long-period fiber grating (MLPFG) made by applying pressure by means a screw to a pair of grooved plates over single-mode fiber. We used a torquemeter in order to obtain precision in the adjustment screw and thus establish an equilibrium pressure applied to a specific region of the optical fiber to form the long-period grating mechanically induced fiber. The increase the torque to screw, the resonance wavelength of MLPFG increases its depth over 16 dB. We use a detector to observe the changes amplitude according to the fiber pressure.
Mechanically induced long-period gratings in polarization maintaining photonic crystal fiber with a supercontinuum gener...Published: 05 September 2014 by SPIE-Intl Soc Optical Eng in Optical Engineering + Applications
We present the results from the fabrication and characterization of mechanically induced long period fiber gratings in polarization maintaining photonic crystal fiber (PM-PCF). A supercontinuum source in the range of 600nm - 1700nm is used. This source is generated using a micro-chip laser at 1064nm and a single mode fiber. A long-period grating is induced over 40mm long unjacketed PCF using a V-grooved aluminum plate. External pressure is gradually applied with a metal screw and a torque meter and a loss dip with resonance wavelength is observed. Low insertion losses are depicted from (1-3) dBm with a bandwidth of about 30nm and a loss dip around 15dBm. Sensitivity for this preliminary work is found at 27 dB/Lb. Several applications are potentially possible with the optimization of the transmission spectrum controlled by applied pressure.
Experimental analysis of the interaction between modulation instability and stimulated raman scattering in short lengths...Published: 01 February 2014 by Institute of Electrical and Electronics Engineers (IEEE) in 2014 International Conference on Electronics, Communications and Computers (CONIELECOMP)
In this work the interaction between modulation instability (MI) and stimulated Raman Scattering (SRS) in conventional short fibers (8m) to supercontinuum generation is reported. Here we used short length optical fibers pumped with a microchip laser emitting a pulsed signal at 1064 nm wavelength and 700ps. Moreover was obtained a detailed analysis of spectral evolution of pulses propagated through the fiber. Hence MI is observed as first nonlinear effect unchaining more of those until reach a 293 nm wide spectrum. A comparative analysis was done between 1060XP and SM28 short section optic fibers showing important SRS gaining differences, achieving on SMF28 fiber a higher gain on anti-Stokes wavelength. On the other side was achieved a higher broadening spectral on 1060XP fiber than the one generated on communications optical.
A tunable multi-wavelength erbium doped fiber laser based on a Mach–Zehnder interferometer and photonic crystal fiberPublished: 18 November 2013 by IOP Publishing in Laser Physics
Highly sensitive curvature and displacement sensing setup based on an all fiber micro Fabry–Perot interferometerPublished: 01 November 2013 by Elsevier BV in Optics Communications
A novel torsion sensor based on a Mach-Zehnder interferometer is presented. The interferometer is made with a piece of Ytterbium doped photonic crystal fiber (YbDPCF) spliced between two single-mode fibers. The torsion sensitivity obtained is 0.05nm/º in a torsion range from 0° to 360° along with a sensitivity of 0.06dBm/º at specific wavelength. The interference fringes and torsion characteristics have been experimentally investigated and demonstrated. This compact fiber component with acceptable sensing performance makes its a good candidate for the measurement of numerous physical parameters. © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Determination of refraction nonlinear index, for effect thermal, of solutions with nanoparticles of goldPublished: 10 September 2013 by SPIE-Intl Soc Optical Eng in SPIE Organic Photonics + Electronics
Research of nonlinear optical properties of materials for manufacturing opto-electronic devices, had a great growth in the last years. The solutions with nanoparticle metals present nonlinear optical properties. In this work we present the results of characterizing, analyzing and determining the magnitude and sign of the nonlinear refractive index, using the z-scan technique in solutions with nanoparticles of gold, lipoic acid and sodium chloride. We used a continuous Argon laser at 514 nm with variable power, an 18 cms lens, and a chopper. We determined the nonlinear refractive index in the order of 10-9. These materials have potential applications mainly as optical limiters. © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
In this work an Intrinsic Fabry-Perot Interferometer (IFPI) based on an air-microcavity is presented. Here the air microcavity, with silica walls, is formed at a segment of a hollow core photonic crystal fiber (HCPCF), which is fusion spliced with a single mode fiber (SMF). Moreover, the spectral response of the IFPI is experimentally characterized and some results are provided. Finally, the viability to use the IFPI to implement a simple, compact size, and low cost refractive index sensor is briefly analyzed.
Experimental study on a broad and flat supercontinuum spectrum generated through a system of two PCFsPublished: 14 May 2013 by IOP Publishing in Laser Physics Letters
In this work we present the study of nonlinear optical properties of Au nanoparticles suspended in different solutions, using the z-scan technique. Thermal lens model and Shiek-Bahae formalism were used to determine the nonlinear properties. Parameters as the sign and nonlinear refractive index n2 , nonlinear absorption coefficient (β) and dn/dt were found. Analyses of changes in these parameters using different solutions with the same concentration of Au nanoparticles are shown.
Generation of a spectrum with high flatness and high bandwidth in a short length of telecom fiber using microchip laserPublished: 01 April 2013 by Elsevier BV in Optics Communications
A compact high temperature fiber sensor where the sensor head consists of a short fattened long period fiber grating (F-LPFG) of at least 2 mm in length and background loss of −5 dBm is reported. On purpose two different F-LPFGs were used to measure temperature variations, taking advantage of their broad spectrum and the slope characteristics of the erbium light source. This approach affected the spectrum gain as the linear band shifting took place. The measured sensitivity of the long period fiber gratings were about 72 pm/°C in a range from 25 to 500 °C. Here, the temperature rate of the experiment was 0.17 °C/s and the temperature response time was within 3 s. Moreover, temperature changes were detected with an InGaAs photodetector, where a sensitivity of 0.05 mV/°C was achieved.
Research nonlinear optical properties of the materials for the fabrication of opto-electronic devices have growth in the last years. Ionics liquids present nonlinear optical properties. In this work we present the results of nonlinear optical properties of four ionic liquids of 1-methylpyrrolidine family, analyzed using a z-scan technique. The results show the difference obtained using or not a chooper for measuring the nonlinearity and the photoinduced lens. Ionic liquids have a negative nonlinearity (self-defocusing) of thermal origin. © (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Fabrication of Mach-Zehnder interferometers with conventional fiber optics in detection applications of micro-displaceme...Published: 13 September 2012 by SPIE-Intl Soc Optical Eng in Optical Engineering + Applications
In this paper we shows the results obtained to fabricate and implement Mach-Zehnder interferometers of conventional fiber optic using Long Period Fiber Gratings (LPFG´s) which were developed by electric arc technique. We obtains this type of interferometer when we fabricated two LPFG’s in series or in cascade with the same characteristics such as number of discharges and the same period, placing them in cascade separated by a distance which three times the length of the LPFG. The application which was given at interferometer fabricated was as a liquids sensor, volume sensor of liquids and micro-displacement sensor. The sensors of liquids and liquids volumes were placed in a container in which the interferometer is fixed so that results of measurements are only by incorporating each of the liquid and not by some external movement. The sensed fluids were: water, alcohol and solution (water with sugar). Final length of the interferometer is between 4 to 6 cm. We analyze the results obtained to when a section the Mach-Zehnder interferometer is displaced in of the order of microns. The variations observed in transmission spectra obtained from each of the sensors mentioned, show changes in the amplitude and the attenuation peak of the interferometer was displaced. © (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Numerical analysis of a broadband spectrum generated in a standard fiber by noise-like pulses from a passively mode-lock...Published: 01 April 2012 by Elsevier BV in Optics Communications
We reported Supercontinuum (SC) generation in standard telecom fiber using picosecond pulses of microchip laser. The pulses width is 700 ps at 1064 nm, using 57 m long of standard fiber, and the spectra extend from 700 to above 1700 nm, some 100 nm further into the visible. The physical processes leading to the formation of the continuum spectrum were studied by monitoring the growth of the SC while increasing the input power. The coupling efficiency of ours experimental setup between the microchip laser and the telecom fiber helped us to obtain this wide spectrum.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Supercontinuum generation is being widely studied due to its applications in communications, medicine and metrology. Usually, special fibers, such as photonic crystal fibers and dispersion-shifted fiber, have been utilized. However, there is few information about the potential use of standard fiber with this purpose, which shows some advantages: low cost and availability. In this work, the influence of losses due to induced macrobends on the supercontinuum generation using standard fiber was studied. The losses were introduced by wrapping 30 m in length of standard fiber on cylinders with different diameter, a nanosecond microchip laser and 1064 nm of wavelength were employed. The continuum was recorded at the fiber output by using an optical spectrum analyzer and its dynamics was analyzed by tuning the launched power. In a first stage, the fiber was used without bends generating strong firs-order Raman Stokes and a supercontinuum spectrum of 636 nm. When the fiber was wrapped in a cylinder of 0.9 cm of diameter to induce macrobends, the Raman Stokes of high order were attenuated and the output spectrum was reduced to 240 nm. Also, a peak pulse was observed, around 1030 nm, that means new frequencies were generated in the near infrared region. Thus, induced macrobends affect the supercontinuum broadening.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
We study experimentally and numerically the transient behavior of a (2+1)D beam when it is totally reflected by nonlinear interface formed by SBN61:Ce photorefractive crystal. The dynamics give rise to observation of new beams. Due to modulation instability of the beam, the nonlinear interface stimulates the break of the beam into new beams that are reflected to different angles.
Supercontinuum generation in a standard fiber pumped by noise-like pulses from a figure-eight fiber laserPublished: 24 October 2011 by Pleiades Publishing Ltd in Laser Physics
We report the experimental study of broadband spectrum generation in a piece of standard fiber (SMF-28) using as the pump a train of noise-like pulses, or sub-nanosecond packets of sub-ps pulses with randomly varying amplitudes. The pulses are generated by an erbium-doped figure-eight fiber laser, and present a wide (∼50 nm) optical spectrum, which represents a significant advantage to seed the generation of new frequencies. Another advantage of the pulses is their relatively large energy, as they are made up of a large number of ultrashort pulses. After amplification with an Erbium Doped Fiber Amplifier (EDFA), the pulses were injected in a 0.75 km length of SMF-28 fiber. We obtained experimentally at the end of the fiber an output signal spectrum extending from 1530 nm to at least 1750 nm (the upper limit of the spectrum analyzer) for pump pulses with an average power of 20.4 mW, corresponding to a few kilowatts peak power. The spectral broadening is due to Raman self-frequency shift (SFS). It is noteworthy that the spectrum of the newly created frequencies was extremely uniform over the range of measurement. Considering that the Raman shift is directly related to the pump pulse duration, spectral flatness is a direct consequence of the random distribution of amplitudes and durations of the pulses in the packet. Finally, the results show the capabilities of noise-like pulses from a fiber laser for applications in supercontinuum generation based on nonlinear phenomena such as Raman SFS.
This article presents the fabrication of Long Period Gratings in Optical Fiber (LPFGs) applied to the sensing loops. In implementing the manufacturing method used a commercial splicer fiber optic (FiTel S-175), capable of being programmed to a short section of standard optical fiber (SMF28) is taken at intervals between shots in a range from 400μm to of 650μm. The LPFGs Being able to obtain through attenuation bands above 20 dB, while the wavelength of central attenuation is close to 1550nm. We shows the experimental scheme to measure curvatures with diameters ranging between 12 and 13.1cm, having a linear variation of peak output cut at the LPFGs with tuning of 17nm.
In this paper we performed the experimental and numerical study of a passively mode-locked fiber laser that generates packets of sub-picosecond pulses instead of individual pulses. The proposed configuration is a figure-eight fiber laser scheme, which includes a Nonlinear Optical Loop Mirror with polarization asymmetry inserted into a ring cavity. No experimental evidence of self-starting mode locking operation of the laser was observed; however, for proper adjustments of the wave retarders included in the setup, a mechanical stimulation triggers the onset of mode locking. The autocorrelation of the generated pulses shows a narrow sub-picosecond peak riding a large sub-nanosecond pedestal whose intensity is half that of the peak, and the optical spectrum is smooth and wide. We show that contrary to conventional ultrashort pulses, these pulses do not vanish rapidly after propagation through a long dispersive fiber, which makes then attractive for super-continuum generation as well as for applications in metrology. Finally, we study the pulse formation in the laser and present arguments based on experimental data and numerical simulations that the observed pulses are actually sets of a large number of solitons.
We prepare optrodes of fiber optic plastic with sol-gel technique. Suitable concentration of carbone nanotubes (CNTs), phenol red, bromophenol blue and cresol red, design optrodes with fiber optic plastic. The surface charge of silica and the refractive index, which play an important roll on the fiber, modifies the conditions of light propagation into the plastic optical fiber. We use the transmittance to measure the pH of a solution or fluid in a range between 3 and 9.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
We study the transmission of light through different lengths of Hollow-core bandgap fiber. We demonstrate 95% transmission of 5 picosecond pulses at 1064nm through fiber lengths of 1m, but only 77% transmission through longer lengths of 10m. This variation is not consistent with the measured attenuation of the "fundamental" low-loss mode of the fiber as being below 20dB/km in this spectral range, because the light transmitted through the short fiber not exclusively in the fundamental fiber mode. We conclude that great care is required to understand coupling efficiencies using short fiber lengths.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Polarization study on solid core photonic crystal fibers partially sedimented with polyethylene micro-spheres and carbon...Published: 13 October 2010 by SPIE-Intl Soc Optical Eng in Workshop on Specialty Optical Fibers and Their Applications (WSOF-10)
We present an experimental study of light polarization on solid core microstructured optical fibers type (Large Mode Area) LMA-16, LMA-20 and LMA-25. These fibers were partially filled with one micron diameter polyethylene spheres or carbon nanotubes diluted in distilled H2O by capillarity. Polarization characterization was realized on these Photonic Crystal fibers with air filled holes and partially particle filled holes using a He-Ne 633nm central wavelength laser at 10mW. The achieved results were compared using graphical data of every test collected at different exposition dates where the fiber was exposed to particle sedimentation. Results depicted that short time sedimentation of these particles does not change the light polarization leaving from the fiber except for the phase of the beam. On the other hand, longer time particle exposition visibly changes the light phase measured at the end of the photonic crystal fiber with repeatable results.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
We study de nonlinear optical properties of organic materials. Multiple rings appear as a CW Ar laser passes through a nonlinear organic liquid. The rings formation is due to spatial self-phase modulation and is observed with 50 mW of continuous wave of Ar laser. We show the dependence between power and rings formed. As a first approximation to value the nonlinear refractive index we use the number of the rings and power of laser in a cell of 2 mm of length.
We study de nonlinear optical properties of three ionic liquids of family [BMIM]. The ionic liquids are 1-buthyl-3-methylimidazolium tetrafluoroborate, 1-buthyl-3-methylimidazolium trifluoroacetate, and 1-buthyl-3-methylimidazolium Bis((trifluoromethyl)sulfonyl)imide. We calculate the static molecular polarizability (α) and hyperpolarizability (β,γ) using PM3 model and determinate experimentally the third-order nonlinear optical susceptibility χ(3), using z-scan technique. Interest in nonlinear optics has grown in recent years. High performance electro-optic switching elements for telecommunications and optical information processing are based on materials with high nonlinear optical (NLO) properties. This NLO are presents when a laser interacts with the materials, and can be studied at to levels: molecular o bulk.