Introduction of Fiber Optic Coupler with its Benefits & Classification

A fiber optic coupler is an indispensable part of the world of electrical devices. Without these no signals would be transmitted or converted from inputs to outputs. This is the reason these are so important thereby this article discussed about these, introduction, classification and benefits in detail.

Fiber Optic Coupler is an optical cog that is capable of connecting single or multiple fiber ends in order to permit the broadcast of light waves in manifold paths. This optical device is also capable of coalescing two or more inputs into a single output while dividing a single input into two or more outputs. In comparison to a connector or a splice, the signals may be even more attenuated by FOC i.e. Fiber Optic Couplers; this is due to the division of input signal amongst the output ports.

Types of Fiber Optic Coupler

Fiber Optic Couplers are broadly classified into two, the active or passive devices. For the operation of active fiber coupler an external power source is required, conversely no power is needed when it comes to operate the passive fiber optic couplers.

Fiber Optic Couplers can be of different types for instance X couplers, PM Fiber Couplers, combiners, stars, splitters and trees etc. Let’s discuss the function of each of the type of the Fiber Optic Couplers:

Combiners: This type of Fiber Optic Coupler combines two signals and yields single output.

Splitters: These supply multiple (two) outputs by using the single optical signal. The splitters can be categorized into T couplers and Y couplers, with the former having an irregular power distribution and latter with equal power allocation.

Tree Couplers: The Tree couplers execute both the functions of combiners as well as splitters in just one device. This categorization is typically based upon the number of inputs and outputs ports. These are either single input with a multi-output or multi-input with a single output.

PM Coupler: This stands for Polarization Maintaining Fiber Coupler. It is a device which either coalesces the luminosity signals from two PM fibers into a one PM fiber, or splits the light rays from the input PM fiber into multiple output PM fibers. Its applications include PM fiber interferometers, signal monitoring in its systems, and also power sharing in polarization sensitive systems etc.

Star Coupler: The role of star coupler is to distribute power from the inputs to the outputs.

Benefits of Fiber Optical Couplers

There are several benefits of using fiber optic couplers. Such as:

  • Low excess loss,
  • High reliability,
  • High stability,
  • Dual operating window,
  • Low polarization dependent loss,
  • High directivity and Stumpy insertion loss.

The listed benefits of Fiber Optical Couplers make them ideal for many applications for instance community antenna networks, optical communication systems and fiber-to-home technology etc.

 

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Optical Fiber In-line Polarizer & its Fine Features

The significance and value of Optical fibers don’t need any explanations or specifications in the world of electronics and technology. These devices are no doubt the tiny part but are equally important as well as requisite for the effective / efficient working of the machinery and electronic. When we talk about optical fiber In-line polarizer these are the cogs which can never be overlooked.

Optical Fiber In-line Polarizer

Low cost optical fiber In-line polarizer is the device to convert unpolarized light into linearly polarized light. It encompasses both, input as well as output as one input of single mode fiber and one output with polarization maintaining fiber. It can easily be connected conveniently into the optical systems through pigtailed input / output connectors.

Now let’s discuss the fine features of In-line Polarizer:

  • Low insertion loss: in telecommunications, the loss of signal power coming from the insertion of a device into the optical fiber is generally referred to as insertion cost. The insertion cost of the In-line polarization is stumpy and quite lesser than the other similar devices.
  • High extinction ratio: the polarizer especially, the In-line polarizer usually have the high extinction ratio i.e. the ratio of the two optical power levels of a digital signal produced by an ocular source.
  • High return loss: The optical fiber polarizer generates high return loss i.e. the loss of power in the signal reflected / returned by a discontinuity in a broadcast line or ocular fiber.
  • Compactness and light weight: Yet another beneficial feature of an In-line Polarizer is that it is quite compact as well as light weighted. This helps in the placement and execution of the appliance. Its light weight helps it work easily and effortlessly.
  • High stability and reliability: In-line polarizer is always recommended as it is quite stable as well as reliable. Unlike all other types of polarizers, the in-line polarizer has higher stability. This is the reason why companies and industries trust these.

 Beyond all, the optical fiber In-line polarizer is available in market at low costs. There are several organizations which offer and sell the high quality optical fiber solutions at competitive prices and ensure you an effective as well as a durable working.

So, whenever you seek the high quality optical fiber In-line Polarizer, or decide to buy them, make sure you choose a copper-bottomed company to get the best products and high quality services as well as high class solutions at competitive prices!

The significance and value of Optical fibers don’t need any explanations or specifications in the world of electronics and technology. These devices are no doubt the tiny part but are equally important as well as requisite for the effective / efficient working of the machinery and electronic. When we talk about optical fiber In-line polarizer these are the cogs which can never be overlooked.

Optical Fiber In-line Polarizer

Low cost optical fiber In-line polarizer is the device to convert unpolarized light into linearly polarized light. It encompasses both, input as well as output as one input of single mode fiber and one output with polarization maintaining fiber. It can easily be connected conveniently into the optical systems through pigtailed input / output connectors.

Now let’s discuss the fine features of In-line Polarizer:

  • Low insertion loss: in telecommunications, the loss of signal power coming from the insertion of a device into the optical fiber is generally referred to as insertion cost. The insertion cost of the In-line polarization is stumpy and quite lesser than the other similar devices.
  • High extinction ratio: the polarizer especially, the In-line polarizer usually have the high extinction ratio i.e. the ratio of the two optical power levels of a digital signal produced by an ocular source.
  • High return loss: The optical fiber polarizer generates high return loss i.e. the loss of power in the signal reflected / returned by a discontinuity in a broadcast line or ocular fiber.
  • Compactness and light weight: Yet another beneficial feature of an In-line Polarizer is that it is quite compact as well as light weighted. This helps in the placement and execution of the appliance. Its light weight helps it work easily and effortlessly.
  • High stability and reliability: In-line polarizer is always recommended as it is quite stable as well as reliable. Unlike all other types of polarizers, the in-line polarizer has higher stability. This is the reason why companies and industries trust these.

 Beyond all, the optical fiber In-line polarizer is available in market at low costs. There are several organizations which offer and sell the high quality optical fiber solutions at competitive prices and ensure you an effective as well as a durable working.

So, whenever you seek the high quality optical fiber In-line Polarizer, or decide to buy them, make sure you choose a copper-bottomed company to get the best products and high quality services as well as high class solutions at competitive prices!

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Profitability of the Optical Component Business Improved Last Year and It May Set a New Record in 2016

The average profitability of optical passive component and module suppliers was very close to zero over the last 5 years, despite strong demand for optics. Compared to every other level of the industry supply chain, profitability of the optical component manufacturers was the lowest by far.

Financial reports of several suppliers of optics started to show signs of improvement over the last 2-3 quarters. The average profitability of optical component and module vendors was 2% in 2015, compared to a loss of 1% in 2014. There is a good chance for reaching 5-7% profitability in 2016-2017 and setting a new record. The highest profitability achieved so far was 5.5% in 2010, preceded by more than ten years of heavy losses.

Net profit margins in the optical components value chain

May 25, 2016 News_Release_Profitability of the Optical Component Business Improved Last Year and It May Set a New Record in 2016

Source: Public financial reports

Several component vendors restructured their businesses in 2013-2014 and these efforts are starting to pay off now. Accelink, Applied Optoelectronics, Coadna, Neophotonics and Oclaro reported significant improvements in financial performance. Acacia joined the list of publicly traded vendors recently and holds the record with a 17% net margin for 2015. Finisar’s profits started to improve in the second half of 2015 and we expect this trend to continue.

However, the average profitability is likely to stay in the single digits for a while. This industry is very competitive and it is likely to remain so for the next several years. Demanding customers, shorter product lifecycles and investments required to support development of new products are a heavy burden for suppliers. There are close to 40 vendors in the race to offer 100GbE optics to the cloud companies building mega-datacenters. Not many of these vendors will be successful in the long term, but they will continue to put pressure on the profitability of larger publicly traded companies in the industry.

Many start-up companies, betting their future on supplying high-speed optics to cloud vendors, develop products based on silicon photonics and expect that this new technology will give them a sustainable cost advantage. LightCounting’s report on Integrated Optical Devices offers detailed analysis of the opportunities for silicon photonics technology, and recognizes the potential advantages of this technology. However, we expect that a majority of high-speed Ethernet optics used in mega-datacenters will still be based on more established InP and GaAs based optics even in 2021.

Despite all the risks, developing new manufacturing technologies offers a path to sustainable competitive advantage and long-term profitability. Silicon photonics holds a promise for being such a technology. High-valued acquisitions of silicon photonics companies and the recent IPO of Acacia offered much needed success stories for investors. However, the risk remains high. Many other vendors, starting just to ship silicon photonics based products now, will have to prove themselves in 2016-2018.

DK Photonics – www.dkphotonics.com  specializes in designing and manufacturing of high quality optical passive components mainly for telecommunication, fiber sensor and fiber laser applications,such as 1064nm High Power Isolator,1064nm Components, PM Components, (2+1)x1 Pump Combiner,Pump Laser Protector,Mini-size CWDM,100GHz DWDM,Optical Circulator,PM Circulator,PM Isolator,Fused Coupler,Mini Size Fused WDM.

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DK Photonics now can write Fiber Bragg Gratings for fiber lasers on demand

Fiber Bragg Gratings for fiber laser

Laser Mirror Gratings

China, 21th July, 2016: Optical passive components available at DK Photonics are significant in a number of industries such as telecommunication applications, fiber laser, etc. In order to better give our fiber laser customers to do matching service, DK Photonics work with a Chinese optical research institute, after more than half a year’s efforts, and finally produced the FBG Mirrors used for fiber laser.

FBG Mirrors are based on the reflective properties of the Fiber Bragg Grating (FBG) written in the core of an optical fiber waveguide. FBG mirrors’ principal application is to use a high and low reflector to form a stable laser cavity having the lasing wavelength selected by the low reflector.

Fiber Bragg grating (FBG) is a distributed reflector constructed in an optical fiber short segment that allows reflecting particular wavelengths and transmitting the rest of them. The periodic variation of the fiber core refractive index generates a wavelength-specific dielectric mirror, which allows reflecting specific wavelengths. FBG can be used as a high reflector (HR) and output coupler (OC) to make a laser cavity in a fiber laser. Rare earth doped optical fiber increases the laser gain. The major advantage of all-fiber systems where free space mirrors are replaced with a pair of fiber Bragg gratings (FBG’s) is that the realignment process is no longer needed for the entire system functioning period, since FBG is spliced directly to the doped finer and never needs adjusting.

DK Photonics can provide varied wavelengths FBG, such as 1018nm, 1053nm, 1064nm, 1080nm, 1550nm, 1950nm, 2020nm, 2040nm; and can write in all common passive optical fibers, such as 6/125DCF,10/125DCF,15/130DCF,20/125DCF,25/250DCF,30/250DCF,20/400DC Fiber, PM or non-PM types are available. The Max. handling power up to 1000W. The following is main parameter or our FBG:

Parameters Values
Center Wavelength(nm) 1018nm, 1053nm, 1064nm, 1080nm, 1550nm, 1950nm, 2020nm, 2040nm
Wavelength accuracy 0.2nm
High Re­ector / Output Coupler HR OC
Reflectivity ≥99% 3%~20%
Bandwidth 1~3nm 0.2~1nm
Fiber Type 10/125 DCF,15/130DCF, 20/125 DCF,25/250 DCF,30/250 DCF,20/400 DC Fiber, PM or non-PM types are available
Power Handling(core) 20W, 50W, 100W, 500W,1000W.

Applications

FBGs offer multiple applications. It can replace conventional dielectric mirrors to provide optical feedback. It can be also used to create a multi-wavelength Raman fiber laser.

Fiber lasers offer a compact, electrically efficient alternative to Ar-Kr and Nd:YAG technologies. The FBG can be applied to fiber lasers of any type:

  • Single frequency fiber lasers;
  • Raman fiber laser;
  • Fixed frequency visible wavelength lasers;
  • Tunable frequency visible wavelength lasers;
  • Ytterbium doped fiber lasers;
  • Q-switched fiber lasers;
  • Pulsed fiber lasers;
  • Stabilized multi-mode emission sources;
  • Fine optical fiber responder, etc.

To obtain more information about the products, visit http://www.dkphotonics.com/.

About DK Photonics

The DK Photonics claims that they even provide customized solutions to their patrons. Those industries who wish their products to be distinctive can contact them for the same. The team mentions that they have passed the ISO9001 quality tests and hence, there is no compromise in this aspect.

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Pump and signal combiner for bi-directional pumping of all-fiber lasers and amplifiers(10)

7. Signal feedthrough of the fiber combiner

Besides the pump power handling and the pump coupling efficiency of a fiber combiner, it is important for fiber laser and amplifier applications to maintain the optical properties of the signal light propagating through the fiber combiner. In particular, during the fabrication of the fiber component, externally induced mechanical stress and perhaps a marginal fraction of thermal diffusion of the core dopants [19] can result in a high signal insertion loss in conjunction with a degradation of the signal beam quality. This behavior was expected for large mode area DC fibers with a very low core refractive index (NA ~0.06), and therefore possible beam quality degradations of the signal feedthrough light was investigated (in Section 7.1).

The uninterrupted signal core in the fiber combiner provides the possibility of passing a signal beam through the combiner in forward and backward direction. However, in the case of a backward propagating signal, the pump diodes need sufficient protection against the signal. Thus, in Section 7.2 we investigate the signal to pump isolation of a 4 + 1×1 fiber combiner in a fiber amplifier setup.

7.1 Signal insertion loss and beam quality

In order to determine possible beam quality degradation and a signal insertion loss caused by the signal feedthrough of the combiner, the setup depicted in Fig. 14

fiber combiner

Fig. 14 Setup for beam quality measurements, TF: target fiber, PBS: polarization beam splitter.was used. A signal at a wavelength of 1064 nm was launched into the core of a 2.75 m long Ytterbium-doped DC fiber (Nufern YDF-25/250), which is specified with a signal core diameter of 25 µm (NA 0.06) and a pump core diameter of 250 µm (NA 0.46). Thus, the parameters of the passive TF of the combiner were matched to the active fiber. The coiling diameter of the active fiber was 12 cm to maintain near diffraction limited beam quality [20]. The transmitted signal had a power of about 200 mW and was propagating in reverse direction through the fiber combiner. The beam quality measurements were carried out with a Fabry-Perot ring-cavity. With this cavity it was possible to determine the power fraction in higher-order transversal cavity modes with respect to the Gaussian TEM00 mode by scanning the length of the ring-cavity over a free spectral range (FSR). A detailed description of the measuring setup can be found in Ref [21]. Due to the use of a polarization sensitive beam quality measurement, a half- and a quarter-wave retardation plate in conjunction with a polarization beam splitter (PBS) were used. The determined polarization extinction ratio was better than 17 dB after the propagation of the signal through the active fiber and the fiber combiner.

Before the fusion splice between the active fiber and the 4 + 1×1 combiner, the power in higher-order modes of the active fiber was determined. This measurement served as a reference beam quality for the active fiber. The mode scan in Fig. 15(a)

fiber combiner 2

Fig. 15 Normalized transmitted intensity through a premode cleaner as a function of the ring-cavity length in units of a free spectral range for (a) the reference beam and (b) the signal feedthrough beam of a 4 + 1×1 fiber combiner.

shows the logarithmic normalized intensity over a free spectral range for the reference beam with a power in higher-order modes of 3.1%. This results in a fundamental fiber mode power of at least 96.9% for the reference beam. For the signal feedthrough of the fiber combiner, a power in higher-order modes of only 5.1% was found (Fig. 15(b)).

Consequently, the signal feedthrough fiber (0.7 m long TF) only led to an increase in power in higher-order transversal modes of maximal 2%. Furthermore, it must be considered that additional power transfer to higher-order transversal modes can also be caused by the fusion splice between the active DC fiber and the TF. Hence, good preservation of the signal beam quality, in conjunction with the low signal insertion loss of less than 3%, provides an excellent high power fiber component for monolithic fiber laser and amplifier systems.

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Work Theory of the Laser Cutting Machine(2)

Cutting methods of laser cutting machine

Vaporization cutting

It means that vaporization is the main way to remove the processed material. In the process of vaporization cutting, workpiece surface is heated to vaporization temperature quickly by focused laser beams, forming High pressure steam and spraying outward at supersonic speeds. In the meantime, a hole is formed in the laser active area and laser beams reflex several times in the hole to increase the absorption of laser pump power combiner by material.

When high-pressure vapors spray outward, the melted materials are blown away in the kerf till the workpiece is finally cut. Vaporization cutting needs very high power density, which is eighth power of ten watt above per square centimeter. It is usually applied in low flash point materials and refractory materials.

Reaction Fusion Cutting

Reaction Fusion Cutting

When assistant airflow not only blows the melted materials from the kerf but also has thermal reaction with the workpiece, this is the so-called reaction fusion cutting. Gases that can have reaction with workpiece are oxygen or mixture gases containing oxygen. When the surface  temperature of workpiece reach to ignition temperature, strong combustion heat release occurs to improve the laser cutting ability.

Combustion heat release of low carbon steel and stainless steel is 60%. And it is about 90% for reactive metals like titanium.

Compared to vaporization cutting and general fusion cutting, reaction fusion cutting need less laser power density. However, reaction fusion cutting may effect the performance of worpiece since the combustion reaction can lead to chemical reaction on materials.

Fusion Cutting

When adding a assistant airflow system coaxial with laser to  blow the melted materials away from kerf, this kind of cutting is fusion cutting. In fusion fiber coupler cutting, workpiece needn’t to be heated to vaporization temperature so the required laser power density is reduced greatly.

Laser Scribing

It is mainly used in semiconductor materials, in which laser of high power density make a shallow groove in the semiconductor materials of the workpiece and then makes it crack through mechanistic or vibratory methods. The quality is valued by the surface fragments and size of heat affect area.

Cold Chipping

It is a new processing method, which is put forward along with ultraviolet band superpower excimer laser appeared in recent years. The basic theory is that energy of ultraviolet photons is similar to binding energy of many organic materials; this high-energy photons are used to impact bond organic materials thus make it crack, achieving purpose of cutting. This new technology has promising application future, especially in electron industry.

Thermal Stress Cutting

Mechanism of thermal stress cutting is that laser beams heat an area of fragile material to produce evident temperature gradient. The high surface temperature makes expansion and inner lower temperature hinders expansion, forming pulling stress in the surface and radial crushing stress inside. When the two stresses exceed fracture limit strength of the workpiece, crackle appears. And then the workpiece is broken along the normal direction of the crack. It is suitable for glasses and ceramics.

Conclusion: laser cutting machine is a cutting technology of melting and gasifying surface material through focused energy generated by the use of laser specialties and focused lens. It features good cutting quality, high speed, various cutting material and high efficiency.

About DK Photonics

DK Photonics – www.dkphotonics.com  specializes in designing and manufacturing of high quality optical passive components mainly for fiber laser applications such as 1064nm high power isolator, Cladding Power Stripper, Multimode High Power Isolator, pump combiner,1064nm Band-pass Filter,(6+1)X1 Pump and Signal Combiner, PM Circulator, PM Isolator, optical Coupler. More information, please contact us.

 

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Work Theory of the Laser Cutting Machine(1)

Laser has been applied in teaching, military as well as industrial production. Laser cutting machine is one of the applications. It can be used in both metal and non-metal cutting, Melting surface material by laser beam. This article will discuss the work theory of laser cutting machine.

Introduction on the work theory of laser cutting machine

Introduction on the work theory of laser cutting machine.

Laser cutting machine adopts the energy released on the time when laser beam irradiate metal surface. The metal is melt by laser and sinter is blow away by gas. Because laser power is highly focused, only a very little heat effects the other part of metal plate and causes a little or no deformation. Laser can cut any complex shape precisely, which needs no further processing.

Laser source is generally CO2 laser beam high power isolator with operating power of 500~5000W. The power is even lower than that of many household electric heater, and because of lenses and reflectors, laser beams are focused in a very small bit of area. Highly focused energy heat the area quickly and makes the metal plate melted.

Laser cutting machine can cut stainless steal of thickness less than 16mm; when adding oxygen in laser beam, the cutting thickness is 8~10mm but it will generate a thin oxidation film in the cut surface. The maximum thickness is 16mm which leads to larger cutting deviation on the size of components.

Since the advent of laser, numerous laser products have been developed, such as laser printer, laser cosmetic instrument, laser marker, laser cutting machine etc. Due to its late start in China, the laser technology in China is greatly behind the developed countries. Although Chinese manufacturers can produce plenty of laser products, some key parts such as laser tube, driving motor, galvanometer and focus lens are imported products. This leads to an increase on cost thus an increase on consumer’s payment.

In recent years, domestic research and production of  laser products become closer to advanced overseas products with the progress of laser technology in China. Some aspects are even superior to products abroad, which has a leading role in market because of the  advantages of price. Overseas products have absolute predominance in precision machining for its quality on stability and endurance.

Work theory of laser cutting machine

Work theory of laser cutting machine

Laser tube is the core part of laser cutting machine. So, below is an introduction of the most popular laser tube. CO2 laser tube.

Laser tube is composed of hard glasses, so it is fragile. It adopts layer of sleeve construction with discharge tube in the most inside layer. However, the diameter of discharge tube is thicker than laser tube, diffraction between the thickness of discharge tube and the size of flare is in direct ratio; the length of tube is in proportion to output power of discharge tube.  Laser tube generates a large quantity of heat in the operation of laser cutting machine, which influences the normal work. So cold water machine is needed to cool laser tube, ensuring constant temperature for successful running.

Cutting features of laser cutting machine

Advantages of laser cutting:

One — high efficiency

Laser cutting machine is always connected to several numerically-controlled rotary tables to achieve numerical controlled cutting. It only needs to change the NC program to adjust to components of different shapes, which can make 2D cutting as well as 3D cutting.

Two — high speed

When cutting low carbon steel sheets of 2mm thickness, the speed of 1200W laser cutting is 600cmmin; when it is 5mm thick polypropylene resin plate, the cutting speed is 1200cmmin. The material needs no clamping fix in laser cutting process.

Three — high quality cutting

Laser cutting features thin kerf. The two sides of kerf are parallel and the kerf is vertical to the surface. The cutting precision can reach to ±0.05mm. The cutting surface is clean and nice, with roughness of tens of microns. The cut components can even come into use directly without further machining. After laser cutting, the heat effected area is very small and material near to kerf has not been affected, making little deformation, high cutting precicion and perfect geometrical shape

Four — non-contact cutting

Laser cutting is non-contact cutting, which means no tool wear problem. When processing different shapes, there is no need to change tools, the only way is to alter the output parameter of laser. The whole laser cutting process features low noise, little vibration and little pollution.

Five — various cutting material

Compared to oxyacetylene cutting and plasma cutting, laser cutting can be applied on more materials, including metal and non-metal, metal matrix and non-metallic matrix composite, leather, wood as well as fibers.

About DK Photonics

DK Photonics – www.dkphotonics.com  specializes in designing and manufacturing of high quality optical passive components mainly for fiber laser applications such as 1064nm high power isolator, Cladding Power Stripper, Multimode High Power Isolator, pump signal combiner,1064nm Band-pass Filter,(6+1)X1 Pump and Signal Combiner, PM Circulator, PM Isolator, optical Coupler. More information, please contact us.

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Pump and signal combiner for bi-directional pumping of all-fiber lasers and amplifiers(9)

6. Demonstration of 440 W pump power handling

After detailed theoretical and experimental characterization of fiber pump combiners with multiple pump ports, a pump power handling performance test was conducted. For these investigations each pump port of a 4 + 1×1 combiner was connected to a fiber coupled pump diode (nLight Pearl) with an output power of ~110 W at a wavelength of 976 nm. The PFF and the delivery fiber of the pump diode had a core diameter of 105 µm with a NA of 0.22. At each fiber output end of the IF, a pump light stripper was applied to avoid the Fresnel reflection of the TP, and therefore the TP was not measured. Up to the maximum total pump diode power of 440 W, a coupling efficiency of 90.2% was experimentally determined (Fig. 13

fiber pump combiners

Fig. 13 Combined pump power for a 4+1×1 high power fiber combiner, * ratio of coupled power to total diode power in percent.

). In the simulations a slightly higher coupling efficiency of 92.8% was obtained. The difference of 2.6% in simulated and measured pump light coupling must be distributed among TP, PAA and PCT, with simulated values of 3.0, 1.4 and 1.7%, respectively. It can be assumed that the PAA-fraction is higher than 1.4%, since the fibers of the combiner are contaminated with dust particles in spite of intensive cleaning. If we assume for each individual loss mechanism an error of 1% related to the total diode power then PCT was 7.5 W ± 4.4 W, i.e. the coating of the TF and the pump power stripper had to handle this fraction of power.

About DK Photonics

DK Photonics – www.dkphotonics.com  specializes in designing and manufacturing of high qualityoptical passive components mainly for fiber laser applications such as 1064nm high power isolator,Cladding Power Stripper, High Power Isolator,pump combiner,1064nm Band-pass Filter,(6+1)X1 Pump and Signal Combiner,PM Circulator,PM Isolator,optical Coupler.More information,please contact us.

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Pump and signal combiner for bi-directional pumping of all-fiber lasers and amplifiers(8)

Pump and signal combiner for bi-directional pumping of all-fiber lasers and amplifiers(8)

5.2 Simulations of the loss mechanism caused by additional pump ports

As already discussed, the total power loss is comprised of TP, PAA and PCT. Since a TL of 20 mm and a TR of 6 seem to be promising parameters for a fiber combiner with multiple pump ports, Fig. 9

pump combiner

Fig. 9 Simulated losses for a pump combiner with a TL of 20 mm and a TR of 6 providing up to 6 pump ports. Please see Fig. 1for TP, PCT and PAA.

illustrates the behavior of the 3 different loss mechanisms and the total power loss against the number of pump ports. The input pump light NA of the PFFs was 0.22. The simulations clearly show that the TP-fraction as well as the PAA-fraction increase with the total power loss, and the PCT-fraction stays almost constant. The NA-mismatched pump light, which couples into the coating of the target fiber (PCT) can be kept below 1.7%, even up to 6 pump ports. Hence, an increasing number of pump ports and, therefore, scaling of the combined pump power results in additional power losses, but with an insignificant increase of thermal load to the coating of the TF. Of course, due to an increased PAA the combiner housing would be exposed to a higher thermal load, but this can be handled by an adequate thermalconcept. The increased PAA can be explained by pump light rays which couple back from the TF into one of the IFs, further propagate in the converging taper portion of the IF, increase in NA and undergo refraction into the ambient air. The increase of the TP-fraction with additional pump ports can be caused by pump light rays with a low NA which reverse couple into one of the IFs and further propagate there.

Finally, the simulations show that the total pump power loss increases with each additional pump port but the PCT, resulting in thermal load of the TF, does not increase significantly compared to a fiber combiner with a single pump port. In general, for the optical design of a side-pumped coupler with multiple pump ports, a TL as short as possible in conjunction with a TR as low as possible, but still satisfying the required pump coupling efficiency for the desired number of pump ports, ensures efficient pump light combining with low power losses. In contrast, for a single pump port, a longer TL in conjunction with a low TR is advantageous for increasing the pump coupling efficiency and reducing PCT-losses in particular.

5.3 Experimental characterization of pump combiners with multiple pump ports

Since the simulation results indicate that a TL of 20 mm and a TR of 6 are useful taper parameters, fiber combiners with two, four and six pump ports were developed. Each pump port consisted of an IF with a measured TL of 18 mm and a measured TR of 6.7. Each PFF had a NA of 0.15, and to characterize the combiner was connected to a pump diode (Oclaro BMU25) with a pigtail fiber delivering a maximum output power of about 25 W at a wavelength of 976 nm. The delivery fiber of the pump diode had parameters identical to the PFF.

Figure 10(a)

2

Fig. 10 (a) Combined and transmitted power measured for a fiber combiner with 4 pump ports and (b) combined pump power measured for a fiber combiner with 6 pump ports, * ratio of coupled or transmitted power to total diode power in percent.

shows the total diode power with respect to the combined pump power and TP for a fiber combiner with four pump ports. For the combined pump power a coupling efficiency of 92% (93.1% in the simulation) was measured, and the fraction of TP was 3.6% (3.9% in the simulation) compared to the total diode power. Thus, the measured TP of 3.6% was 45% of the total power loss of 8% (Fig. 10(a)). Based on the good agreement between simulation and experiments it can be assumed that the PCT-fraction and PAA-fraction were about 0.6% and 2.3% of the total diode power, respectively.

Microscope images of the top view and of the cross section view, close to the taper waist, of a fiber combiner with 4 pump ports are depicted in Fig. 11(a)

3

Fig. 11 Microscope image of (a) the top view and (b) the cross section view of a fiber combiner with 4 pump ports.

and 11(b).

The experimental results of a developed six pump port fiber combiner with a combined pump power of 141.5 W and an obtained coupling efficiency of 89.6% (91.1% in the simulations) is shown in Fig. 10(b). The fiber combiner with six pump ports was limited by the available pump power and not by thermal problems. For the combiner presented in Fig. 10(b), Fig. 12(a)

4

Fig. 12 (a) Pump coupling efficiency of the individual pump ports of the six pump port fiber combiner presented in Fig. 10(b) and10(b) comparison of the experimentally achieved pump coupling efficiencies with the simulation results for fiber combiners with multiple pump ports.

shows the pump coupling efficiency of each individual pump port with a maximum and minimum pump coupling efficiency of 90.2 and 88.8%. The difference of only 1.4% indicates a very homogeneous fiber bundle structure, and supports the assumption of identical optical behavior of the individual pump ports.

An overview of the experimentally obtained coupling efficiencies with the corresponding simulation results for a fiber combiner with 1, 2, 4 and 6 pump ports is depicted in Fig. 12(b). An agreement of the experimental and simulated results within 1% confirms the applicability of the simulation approach for multiple pump ports. For each fiber combiner a TL of 18 mm, a TR of 6.7 and a PFF with a core NA of 0.15 was applied.

About DK Photonics

DK Photonics – www.dkphotonics.com  specializes in designing and manufacturing of high qualityoptical passive components mainly for fiber laser applications such as 1064nm high power isolator,Cladding Power Stripper,Multimode High Power Isolator,pump combiner,1064nm Band-pass Filter,(6+1)X1 Pump and Signal Combiner,PM Circulator,PM Isolator,optical Coupler.More information,please contact us.

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Fiber Laser Welding: Some Traits and Applications(2)

Technological parameter of laser welding:

(1) Power density

Power density is one of the key parameters in laser processing. When the power density is relatively high, the surface would be heated to boiling point in microseconds, thus generate mass vaporization. As a result, high power density is good for material removal processing such as punching, cutting and carving. When the power density is relatively low, it would take some microseconds to meet the boiling point, the bottom can reach the melting point before vaporization occurs, thus a good melt welding is successfully formed. So the power density ranges from 104~106W/cm2 in conductive laser welding.

(2) Laser pulse shape

Laser pulse shape is an important question in laser welding, especially for foil welding. When high strength laser beam reaches the material surface, 60~98% of the laser energy will be lost by reflection and the reflectivity is changeable by the temperature of the material surface. The reflectivity of metal can vary greatly in a laser pulse period.

(3) Laser pulse width

Laser pulse width is an important parameter to distinguish material removal and material melting; it is also a key parameter to decide the cost and volume of processing equipment.

(4) Influence of defocusing amount on weld quality

There are two ways of defocus: positive defocus and negative defocus. It is positive defocus when focal plane is above the workpieces, vise versa. According to geometry optical theory, when positive and negative defocusing plane equals to welding plane, the power densities are almost the same in the corresponding panels, but the actual laser pools have different forms. It can achieve larger depth of fusion when it is negative defocus.

Application field of laser welding

Laser welding machine has wide application in manufacturing industry, powder metallurgy field, automobile industry, electronics and some other fields.

fiber laser 3

Source : demarlaser

Application of laser welding in automobile industry

Volkswagen AG has adopted laser welding in car roof of brands like AudiA6, GolfA4 and Passat. BMW and GM have used laser welding in top of the car frame while Mercedes-Benz has applied laser welding in drive disk assembly. Except for laser welding, other laser technologies have be applied as well. Companies like Volkswagen GM, Benz and Nissan have used laser to cut covering parts while FIAT and Toyota have adopted laser for coating engine exhaust valve; Volkswagen has used laser for surface hardening on engine camshaft. Domestic vehicle models like Passat, Polo, Touran, Audi, Dongfeng Peugeot and Focus have adopted laser welding technology.

Independent automobile brands like Brilliance, Chery and Geely have adopted laser welding as well.

Improvement and development of new laser welding technology

Laser welding technology is continuously developing along with the progress of the time. The following three technologies can help expanding laser’s application scop and enhancing the automatic control level of laser welding.

  1. filler wire laser welding

Laser welding generally doesn’t fill wires but has high requirement on assembling clearance, which is hard to be guaranteed thus limits the application scope. Filler wire laser welding method has lower requirement on assembling clearance. For example, if the aluminum alloy plate is of 2 mm’s thickness, the clearance must be zero for a good shaping. When adopting φ1.6mm welding wire as filler metal, it can form good shape even the clearance is 1.0 mm. Besides, filler wire can be used for adjusting chemical components and multi-layer welding on thick board.

  1. Beam rotation laser welding

By the adoption of laser beam rotation laser welding methods, demands on welding assembly and beam centering are reduced greatly.

  1. On-line detection and control of laser welding quality

It is becoming a hot researching topic on detecting laser welding process by using plasma such as light, sound and electric charge; some researches have achieved closed-loop control.

DK Photonics – www.dkphotonics.com  specializes in designing and manufacturing of high quality optical passive components mainly for fiber laser applications such as 1064nm high power isolator, Cladding Power Stripper, Multimode High Power Isolator, pump combiner,1064nm Band-pass Filter,(6+1)X1 Pump and Signal Combiner, PM Circulator, PM Isolator, optical Coupler. More information, please contact us.

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