Tag: optical fiber

Ytterbium Doped Fiber Lasers for spontaneous emission

A team of researchers presents a new random noise pulsed regime provided by a ytterbium doped fiber laser. Herewith, the output of the ytterbium laser complies with the photon statistics common to narrowband amplified spontaneous emission resulting in the noise pulsing in terms of probability density and autocorrelation functions. The new fiber laser technique demonstrates that the increase of ytterbium doped laser leads to a prominent decrease in the regime’s coherence time (from few ns to tens ps).

Fiber laser systems are regarded as highly promising tools that have a wide range of commercial applications. Fiber lasers are used as light sources in fully fiberized optical schemes with no free-space components. Herein, they offer a high level of optical and electrical to optical conversion efficiency. Additionally, fiber laser systems have various operating regimes, “characterized by narrow (from a tens Hz) to a very large optical band, in continuous-wave (CW) and pulsed regimes including Q-switched, mode-locking and soliton operations where the pulse width is ranged from hundreds of nanoseconds down to tens of femtoseconds”.

Ytterbium doped fiber lasers are considered to have such a benefit as an excellent power budget thanks to the absence of excited-state absorption. Nevertheless, ytterbium doped lasers have a disadvantage that influences their efficiency: there is a specific broadening of the laser line in the case when the cavity of fiber laser is made from FBG couplers. Thus, the partial leakage of fiber laser power occurs on highly reflective fiber Bragg gratings.
The output power of ytterbium doped fiber lasers may vary from several watts to tens kW or even a few hundred kW depending on single-mode and multimode operations. It should be noted that the low cavity Q-factor of ytterbium lasers causes high fiber laser gain, and the regime of the laser system is changed on random kW pulses resulting in Brillouin scattering.

The researchers confirm that the operation of ytterbium doped lasers happens in a noise pulse regime with random magnitudes and widths (not in the CW regime). Moreover, there is a dependence between the fiber laser photon statistics and laser beam power (and hence on laser linewidth), thus, its behavior seems similar to narrowband ASE. For instance, several high-amplitude noise events with low probability achieve powers more than the mean laser beam power.

Finally, the developed laser system has been already tested. It shows that the laser spectrum’s width becomes higher with increasing output power. While the rate of the ytterbium laser process at lower output powers is lower than at higher one. Taking into consideration the fact that the nonlinear optical fiber length is considerably shorter than the cavity one.

Optromix is a fast-growing fiber laser manufacturer and a vendor of optical fiber sensors and optical monitoring systems. The company offers fast turnkey solutions and creates sophisticated fiber laser systems for special purposes. Optromix uses only its technologies and develops a broad variety of fiber lasers. If you have any questions or would like to buy a laser system, please contact us at info@optromix.com

How to choose the best fiber optic cable

The variety of fiber optic cables requires their proper selection, installation, and maintenance to optimize it. Optical fibers are flexible and they allow installing fiber optic probes for remote measurement at numerous points with one device, significantly reducing cost. Moreover, optical fibers matched to the spectroscopic analyzer system enable us to reach optimal performance results.

You should pay careful attention to the following parameters when choosing the right fiber optic cables:

The optical wavelength range of application

It is required for the spectroscopic optical fiber generally to be much larger in diameter. The operating principle of fiber cables is based on the total internal reflection of the light. “The core of the optical fiber is typically high purity fused silica surrounded by a higher index of refraction doped fused silica cladding layer.” Herewith, the spectroscopic grade optical fibers are optimized for the wavelengths of application.

The diameter of fiber optic cables

Various core diameters of optical fibers are distinguished, for instance, single-mode fiber is about 6 µm in diameter, while multimode optical fiber is up to 1000 µm in diameter. The thing is that huge core fiber costs higher, it has less flexibility and a higher attenuation rate with distance but such optical fiber allows transmitting more light and providing a better signal-to-noise ratio.

Environmental conditions

Usually, optical fibers are highly fragile, that is why special protective layers are used to solve this problem. Different environmental conditions need for various protective coatings. Moreover, environmental conditions influence the optical fiber performance in a spectroscopic application. For example, strong sunlight may disturb the optical fiber leading to incorrect results of the analysis.

Required distances for the transmission of the signal

It is necessary to install the analyzer far enough away from the hazardous process to be safe, however, close enough to make the optical fiber run practical from cost and performance points of view because fiber optic cables are quite expensive. Thus, the cost depends on the distance required for the optical fiber significantly if it is installed in a protective conduit.

Installation recommendations

Proper installation of fiber optic cables is recommended for better performance. Also, it is necessary to avoid sharp bends as well as vibrations. They can evoke noise in the signal because they are a form of micro-bend losses. The most important thing is the correct termination of fiber cables. For optimal application in spectroscopic applications, the connectors of optical fibers must be polished to perfection, be flat, square-ended, and have the correct length.

Optromix is a provider of top quality special fibers and broad spectra optical fiber solutions. The company delivers the best quality special fibers and fiber cables, fiber optic bundles, spectroscopy fiber optic probes, probe couplers, and accessories for process spectroscopy to clients. If you have any questions or would like to buy an optical fiber product, please contact us at info@optromix.com

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Devices based on fiber optic technology

Optical fibers are flexible waveguides of the optical range. Usually made of some kind of glass, they can potentially be very long (achieving hundreds of kilometers). Quartz glass is most often used for the manufacture of optical fibers because of its unique properties, in particular:

extremely low energy losses of radiation propagating in it (realized only in ultra-pure material);
surprisingly high mechanical tensile and bending strength.

Most optical fibers used in laser optics have a core with a refractive index slightly higher than that of the outer layer (the so-called shell). Light introduced into the optical fiber is distributed mainly in the region of its core, although some of the radiation can also penetrate into the shell. Light is retained in the fiber due to the effect of full internal reflection at the border of regions with different refractive index, or due to the gradient of the refractive index in the core of the optical fiber.

They less commonly use fibers that implement a different principle of light retention in them. Such optical fibers are based on the fiber Bragg grating structures and photonic crystals to form a photonic stop-band. This technique is fundamentally different from the method of retaining light in conventional fibers.

To be more precise, a fiber Bragg grating is a periodic or aperiodic perturbation of the effective refractive index in the fiber core. As a rule, the Bragg grating has a length of about a few millimeters or centimeters. The width of the reflection band of the fiber Bragg grating, which is usually much less than 1 nm, depends on both the length of the Bragg grating and the depth of the refractive index modulation. Narrow-band gratings required, for example, for the manufacture of single-frequency fiber lasers or for certain optical filters can be obtained using long gratings with weak modulation. Wide reflection bands can be obtained on short Bragg gratings with deep modulation, but also on gratings with aperiodic modulation.

Since the maximum reflection wavelength depends not only on the Bragg grating period but also on temperature and mechanical stresses, fiber Bragg gratings can be used in temperature and stress sensors. Transverse stresses compress the optical fibers of gratings between two flat plates, inducing birefringence and thus causing the Bragg wavelength to depend on polarization.

Additionally, fiber Bragg gratings are often used for the development of fiber optic sensors. Fiber optic sensors are fiber optic systems for detecting certain factors, usually temperature or mechanical stress, but sometimes also displacement, vibration, pressure, acceleration, rotation, and chemical concentrations.

Optromix is a fast-growing vendor of fiber Bragg grating (FBG) product line such as fiber Bragg grating sensors, FBG interrogators and multiplexers, Distributed Acoustic Sensing (DAS) systems, Distributed Temperature Sensing (DTS) systems. The company creates and supplies a broad variety of fiber optic solutions for monitoring worldwide. If you are interested in structural health monitoring systems and want to learn more, please contact us at info@optromix.com

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Tapered optical fibers change the future of laser system processing

Nowadays new fiber laser technology allows transmitting multikilowatt power, ultrashort pulse durations, repetition rates up to 1 GHz, and high laser beam quality in a compact version. The thing is that the ultrafast laser system with pulse durations in the femtosecond and picosecond range is widely used in numerous industrial processes.

Benefits of these fiber lasers provided high-quality, virtually athermal materials processing combining with developments in fiber laser technology, process development, laser beam handling, and delivery, enlarge fields for many advanced scientific and industrial applications. Nevertheless, tapered optical fibers provide high laser beam power with perfect beam features in a space-effective format, herewith, at not expensive production costs that are slightly more than traditional optical fibers.

Thus, these ultrafast fiber laser systems offer fast industrial performance by transmitting fast investment returns from high processing speed and accuracy. It should be noted that the rapid rise in output laser beam power due to rare-earth-doped optical fiber allows designing new fiber optic systems with perfect performance (high laser beam quality, overall efficiency, and flexibility in operating wavelength and radiation format).

The thing is that current fiber optic technologies promote creating new configurations as well, however, the cost of solid-state gain material is high, combined with thermal management challenges cause crucial obstacles to its widespread application. The popularity of pulsed laser systems increases every day. Solid-state, disk, and fiber lasers are considered to be the most potential versions for high-average-power generation, herein, fiber laser systems are in advance.

Compared to solid-state and disk laser systems, fiber lasers provide such advantages as compactness, robustness, efficiency, ease of thermal management, and reliable laser beam quality. Additionally, fiber laser systems have greatly lower production and maintenance costs beneficial for pico- and femtosecond high-repetition-rate kilowatt-level laser beam development. Modern high-average-power fiber lasers usually apply chirped-pulse amplification.

Nevertheless, even amplifiers based on fiber optic technology can provoke very high optical peak intensities leading to detrimental nonlinear laser beam pulse distortion or even destruction of the gain medium or other optical fiber elements. Moreover, there are various nonlinear effects (self-phase modulation, stimulated Raman scattering, mode instabilities, and poor output laser beam quality) that increase in pulsed high-power laser systems limiting their performance. The promising solution is the increase in the core diameter of the optical fiber.

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SME 2016 Exhibition, Phoenix, Arizona 23-24 SME Phoenix

Founded in 1898, the Canadian Institute of Mining, Metallurgy, and Petroleum (CIM) is the leading technical society of professionals in the Canadian Minerals, Metals, Materials and Energy Industries.

Fibreglass exterior doors won’t delaminate, split or rot like wood. They offer an advantage in that fiberglass can easily be manufactured in a wider variety of shapes, textures, and new design treatments, down to accurately replicating real wood grain

The friends set themselves the challenge of learning a language in a week in order to stretch themselves, and then it was a question of choosing which language to learn. English presented itself as a natural option; there are nigh on 300,000 English speakers in Germany’s capital, and the areas are dotted with stores adorned with signs in English.

“TRULY UNDERSTANDING ONE’S ENVIRONMENT REQUIRES ONE TO FIRST UNDERSTAND ENGLISH”

The first operational step in the friends learning process was to decorate the entire apartment with sticky notes. This had an almost ceremonial touch to it as the friends delved into dictionaries and proceeded to label everything with its corresponding English name.

Within the space of about an hour it was impossible to carry out any menial task, be it making a coffee or flicking off a light switch, without first being presented with at least three different words related to this action.

The friends simply switched their everyday conversations to English

The importance of the other twin’s presence became immediately apparent as Katy and Sara delegated responsibilities for rooms to decorate with sticky notes. This simple task was augmented by continuous little tests that they would spring on one another, and the fact that they split up their day slightly differently and studied different topics meant that each twin became a source of knowledge for the other.

The most extraordinary moment came towards the end of the week!

The friends simply switched their everyday conversations to English, asking one another if they wanted tea or coffee, were ready to cook dinner or when they were going to leave the house.

Katy and Sara had numerous micro-challenges throughout the week. On the first day they were visited by a English friend who greeted them in English and complimented them on how quickly they’d picked up their first words and phrases.

They then learned the names of fruits and the numbers from one to a billion so that they could visit the English market (although they refrained from purchasing nine hundred thousand kumquats). Displaying their haul after their first functional exchange in English, they beamed with pride and a palpable sense of accomplishment before marching back home to study further.

There is no definitive method to learn a language fluently

On our second visit to the brother’s apartment 24 hours into the week, we found them sampling dozens of different kinds of English snacks.

Like kids staring at the backs of cereal packs before heading to school, the nutritional information and various special offers and competitions on the packaging were analysed during snack breaks.

There was no moment of complete removal from the language learning process during the eight hours that the friends had allotted to it.

They were constantly using their existing knowledge to support the ever-growing knowledge of English, this being the root of their success.

“YOU WILL LIKELY COME ACROSS WORDS THAT SHARE COMMON ORIGINS WITH YOUR NATIVE TONGUE”

The friends spent a lot of time engrossed in books or on their computers and apps, flicking and swiping their way through exercises eagerly, but at other times they were to be found searching busily for English radio stations and write-ups of English football games on the web.

All too often, people enter their weekly language class to converse with their teacher, but then barely have any contact with other speakers and that’s not enough.

The old saying that we can solve problems more effectively when we sleep on it may be especially true if the problem we’re trying to solve is learning a new language.

The researchers added a techie dimension by conducting electroencephalographic (EEG)recordings of the sleeping participants brains to track neural electrical activity during the learning period.

They found that learning the foreign words overlapped with the appearance of theta brain waves, an intriguing result since theta is the brain wave state often associated with heightened learning while awake (usually we’re in either the high-frequency, high-alertness alpha or beta states while awake, but it’s thought possible to induce theta state slower in frequency than alpha and beta through concentration techniques).

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