This work shows the development of a fiber optic taper machine by applying a controlled melting temperature, which is induced by a 30W CO2 laser. The laser is made to influence the fiber, heating it and making it malleable. Then the tension axis of the device moves, having three independent axes X, Y and Z on the laser system, it is possible to mark the fiber in order of generate gratings. The device was designed entirely with low-cost materials, which are made for process optimization, such as resources. The software implemented is designed in Arduino for an IOT card that operates with HTML interface, is controlled from a website with which different variables can be handled for the operation of the taper machine, such as distance, speed and time. The device is controlled by means of Wi-Fi, through a website generating accessibility to the free operation of the engines, which can be executed over the same network. The machine has an aluminum base on which are two endless screws, connected each to a step-by-step motor that when turning in opposite directions move each one, a Fiber Holding Blocks on which the fiber is held to be stretched. The electronic circuit is located in a box attached to the motor system.
A low-cost biosensor for glucose analysis was designed, fabricated and characterized. It was fabricated by using a DLPdirect light processing, 3D printed technique. The operation principle for the electro-optic device is based on the total internal reflection. The photosensitive resin is considered that is doped with nanoparticles such as quantum dots and carbon nanotubes as a waveguide. By using DLP 3D printing technique the device was fabricated. The operation principle was based on the optical phase shift. The entire structure of the device features a Mach-Zehnder Interferometer (MZI) that was numerically analyzed in a commercial software featuring finite element. The biosensor works in the transmission scheme. Mach-Zehnder interferometer is composed of a waveguide that encompasses the resin doped with nanodots that linked both input and output signals. In contrast, one arm is kept isolated and the other arm exposed to the medium in order to obtain the phase change at the MZI output. A laser-diode of 980 nm was considered as the source. The optical array features a single-mode optic fiber and a bidirectional coupler. While tested, several glucose concentrations (from 0% to 3%) were provided in order to determine the relationship between the glucose concentration and the output signal in order to increase the sensitivity. The future possibility of the aforementioned structure describes the use of several materials for biological-related applications are also discussed.
We report an experimental study erbium-doped fiber laser for gas pressure detection in the L-band wavelength region by laser intracavity absorption spectroscopy. By using a high-birefringence fiber optical loop mirror as spectral filter within the ring cavity laser, the wavelength of the generated laser line is finely selected and tuned in a range of ~10 nm in order to select the wavelength where the gas absorption line is exhibited. Experimental results for detection of CO2 pressure with absorption at 1573.2 nm are shown and discussed. The proposed fiber laser sensor exhibits reliability and stability for gas detection with absorption in the L-band such as CO2, CO, and H2S.
We report an in-fiber structure based on the use of a multimode fiber segment and a double cladding fiber segment, and its application as spectral filter in an erbium-doped fiber laser for selection and tuning of the laser line wavelength. The output transmission of the proposed device exhibit spectrum modulation of the input signal with free spectral range of ~21 nm and maximum visibility enhanced to more than ~20 dB. The output spectrum of the in-fiber filter is wavelength displaced by bending application which allows a wavelength tuning of the generated laser line in a range of ~12 nm. The use of the proposed in-fiber structure is demonstrated as a reliable, simple, and low-cost wavelength filter for tunable fiber lasers design and optical instrumentation applications.
We present a wavelength tuning of an Erbium-Doped Fiber Ring Laser (EDFRL) based in a Mach-Zehnder fiber interferometer (MZFI) that consists on two tapers fabricated on commercial SMF28 from Corning as an intracavity filter. The MZFI spectral interference pattern is modified by external refractive index changes that alter the light transmission characteristics. In this work, the fiber device is immersed into a glycerol solution with higher dispersion in its refractive index in relation with temperature. Since the temperature sensitiveness of the glycerol is much higher than that of the fiber in a temperature range from 25-110 °C, therefore, the spectral changes are mainly due to the dispersion of glycerol refractive index when heat increases. Also, when this device is inserted into the EDFRL cavity, the gain spectrum of the EDF is modified accordingly and the changes, which can be controlled in an electrical heater, allow the tuning of the laser wavelength determined by the interference fringes. A wavelength shift as high as 180 pm/°C and a tunable range of 12 nm are obtained. The side mode suppression ratio (SMSR) of the fiber laser is around 25-30 dB depending on the notch filtering position. The insertion losses of the filter are below 0.3 dB and the measured wavelength shift has a quasilinear dependence as a function of temperature in the 80-110 °C. This method is very simple, portable and inexpensive over traditional methods to tune a fiber laser.
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.
We present a numerical analysis of different fiber termination shapes in order to study the maximum numerical aperture that can be obtained in end emitting plastic optical fibers with diameters around 10 mm. Our analysis includes the modeling of polished fibers with parabolic shape, conical lensed fibers, and wedged fibers with different lengths, angles and curvatures respectively. The optimization of these parameters allows us to obtain a maximum possible angle which the light can be emitted at the plastic fiber end. These results contribute to minimize the use of fiber components in luminaire systems which can be based in solar concentrators coupled to plastic optical fibers, and consequently it allows us to reduce their installation cost. We also analyze the light distribution of the emitted light and the optical tolerances of the parameters above mentioned to evaluate the performance of the optimized fiber lens. These results are of great interest for the improvement and design of compact luminaire systems based in optimized plastic fiber lens for indoor illumination.
We present an experimental characterization of a fiber laser composed by an Yb-doped fiber spliced with a birrefringent
photonic crystal fiber and a mechanically-induced long-period grating (LPG) into the laser cavity. According to the
torsion properties of the LPG induced in the photonic crystal fiber, the Yb-doped fiber laser can be highly sensitive to
twist and it can shown novel properties in its laser emission. Also, we show the splitting of attenuation bands of a longperiod
fiber grating induced mechanically in different twisted photonic crystal fibers with high birefringence and their
applications on the performance of tunable and switchable multiwavelength double-clad Ytterbium-doped fiber lasers.
The thermal effect of an Yb-doped fiber laser with fattening is numerically investigated. We have identified two principal sources of thermal sensitivity: The temperature dependence of the cross-section of the pump and signal radiations, and modifications of the numerical aperture (NA) due to changes in temperature. We have found that the first factor affects principally the thermal response of the fiber laser with fattening and this sensitivity can be modulated according to the fattening ratio. Additionally this thermal response is higher than that found in doped fibers without fattening. Our results are reproducible and contribute with new information for the development of novel temperature fiber laser sensors
We report the numerical investigation of an Yb-doped fiber amplifier with a taper end in order to be used as a thermal sensor. The spectral fluorescence intensity of the Yb-doped fiber is highly modified when the tapered end is subject to different temperatures from 20 to 150°C, and these changes are more sensitive than that presented in untapered doped fibers. This enhanced temperature response is attributed to the taper effects on the temperature dependence of the crosssections of the pump and signal radiations and additional changes of the numerical aperture of the doped tapered core due to temperature. These results can be extrapolated to other doped fibers and contribute with new information for the development of temperature fiber laser sensors.
This works describes a novel optical refraction index sensor which is based on the analysis of double reflection lecture
detection. This process initially identifies the thickness of a semitransparent solid o liquid material by the retro-reflection
of a laser diode at 633nm as a function of distance along the device under test with a Z-axis scanner to find the focusing
point. This feedback signal brings how far traveled the beam path which is indirectly related with the refractive index at
different materials, the data of the thickness at each layer is treating with a geometrical analysis of the beam velocity.
KEYWORDS: Fiber optics, Sensors, Reflectometry, Fiber optics tests, Fiber optics sensors, Signal processing, Time metrology, Precision measurement, Electronics, Control systems
A sensor instrument able to measuring the thickness of different semitransparent objects with a resolution of one micron
is described. This is based on a fiber optic reflectometer and a laser autofocus system and permit to measuring the
thickness of thin surfaces such as semiconductor films, plastic materials and semitransparent objects. The response time
for the measuring was roughly 2 sec and the thickness results were compared with a digital mechanical micrometer and
both are in good agreement.
We show an approach to a tunable multi-wavelength fiber laser. The beam bending steel technique has been applied for
our purpose. Variations on the relative distance between the fiber and the steel beam demonstrate alterations on
important laser characteristics like, output power, wavelength shift and wavelength spacing.
We report on a novel tuning mechanism to fabricate an all-fiber tunable laser based on multimode interference (MMI)
effects. It is well known that the wavelength response of MMI devices exhibits a linear dependence when the length of
the multimode fiber (MMF) section. Therefore, tuning in the MMI filter is achieved using a ferrule (capillary tube of 127
μm diameter) filled with a liquid with a higher refractive index than that of the ferrule, which creates a variable liquid
MMF. This liquid MMF is used to increase the effective length of the MMI filter and tuning takes place. Using this
simple scheme, a tuning range of 30 nm was easily achieved, with very small insertion losses. The filter was tested
within a typical Erbium doped fiber (EDF) ring laser cavity, and a tunable EDF laser covering the full C-band was
demonstrated. The advantage of our laser is of course the simplicity of the tunable MMI filter, which results in an
inexpensive tunable fiber laser.
The Erbium doped fiber laser (EDFL) has demonstrated to be the ideal source for optical communications due to its
operating wavelength at 1550 nm. Such wavelength matches with the
low-loss region of silica optical fiber. This fact has
caused that the EDFL has become very important in the telecomm industry. This is particularly important for Dense
Wavelength Division Multiplexing (DWDM) which demands the use of single emission sources with different emission
wavelengths. In the long run, this increases the capacity of transmission of information without the necessity to increase
the infrastructure, which makes tunable laser sources an important component in DWDM applications. Many techniques
for tuning have been demonstrated in the state of the art and we can mention, for example, the ones using birefringence
plates, bulk gratings, polarization modified elements, fiber Bragg gratings, and very recently the use of multimode
interference (MMI) effects. The MMI consists in the reproduction of single images at periodic intervals along the
propagation direction of a multimode optical fiber, taking into account that these single images come from a single mode
fiber optic.
Here, a compact, tunable, erbium-doped fiber laser is experimentally demonstrated. The mechanism for tuning is based
on the multimode interference self-imagining effect, which results in a tunable range of 12 nm and optical powers of
1mW within the region of 1549.78-1561.79nm.
We report for the first time, a single mode, tunable, double-clad ytterbium-fiber (YDF) laser emitting in a
wavelength range between 976 and 985 nm that operates using the re-imaging effect that occurs in multimode
interference (MMI) devices. The system consists of an YDF with bare fiber cleaved ends. The forward end of this fiber is
fusion spliced to a piece of 3 m of Samarium-doped- single-mode fiber with absorption measured at 980 nm of 0.3 dB/m,
and at 1030 nm of 6 dB/m. The other end of the Sm+3 doped single-mode fiber is spliced to a 16.2 mm long multimode
fiber (MMF) in order to induce the MMI self-imaging effect. From simulations, we found that, at this particular length,
for the MMF, the light exiting will exhibit a maximum transmission for the 980 nm wavelength, while keeping a
minimum for the 1030 nm wavelength. Near to the MMF facet, at a distance between 0 and 100 µm, we place a dichroic
mirror which also helps in the selection of the wavelength emission. We calculated that 10 dB gain generated at 980 nm
is enough to build up a laser since the total round-trip cavity losses are estimated to be 8.8 dB, whereas for the unwanted
1030nm get more than 60dB insertion loss in this setup. At the end, there is more than 1 dB for the effective gain at the
preferred wavelength emission range which is enough to promote lasing at around 980 nm.
In this work, we propose a set of photonics devices that can be employed as part of optical communications systems.
These devices consist of an isolator, a circulator, a multiplexer and a pump concentrator, and are based on the
functionality of an optical paraboloidal mirror. The devices were first studied using software for optical modeling and
then were experimentally tested. For the cases of the isolator and the circulator, we obtained numerically roughly 50 dB
of isolation. Furthermore, we proposed a simple and a novel multi channel multiplexing device, and finally, we asses the
alternative and elegant way of the combination of high power multimode diode laser to increase the power capability of
diode laser systems that are commonly used in high power fiber laser. In all the cases, the design showed the advantage
of the easiness of alignment and the simplicity to implement.
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