Cladding Power Stripper Archives

Potential of Cladding Power Strippers in Fiber Optic Networks

Introduction

In the fast-paced world of data communication, fiber optic networks have emerged as the backbone of modern telecommunications. The need for high-speed, reliable, and efficient data transmission has led to the evolution of various technologies within the field of fiber optics. One such innovation that has been gaining significant attention is the use of cladding power strippers. In this article, we will explore the potential of cladding power strippers in fiber optic networks and their impact on signal quality, power management, and overall network performance.

Understanding Fiber Optic Networks

What are Fiber Optic Cables?

Fiber optic cables are made of thin strands of optically pure glass or plastic that can transmit data as pulses of light over long distances. These cables are designed to carry large amounts of information with minimal signal loss, making them ideal for high-speed data transmission.

How Do Fiber Optic Networks Work?

In fiber optic networks, data is transmitted using light signals that travel through the core of the optical fiber. The core is surrounded by a layer called the cladding, which helps contain the light within the core by reflecting it inward due to its lower refractive index. This principle of total internal reflection ensures that the light signals can travel through the fiber without significant loss of signal strength.

The Need for Power Strippers in Fiber Optic Networks

As data demands continue to surge, maintaining signal quality and managing power efficiently become critical aspects of fiber optic network design.

Signal Quality and Interference

Signal degradation can occur due to various factors, including attenuation, dispersion, and external interference. Cladding power strippers offer a potential solution to enhance signal purity and minimize the impact of external noise on the transmitted data.

Power Management in High-Speed Networks

High-speed fiber optic networks require precise power management to ensure optimal performance. Cladding power strippers can play a vital role in balancing power levels and preventing signal distortion or loss.

Introducing Cladding Power Strippers

What are Cladding Power Strippers?

Cladding power strippers are specialized devices designed to remove the cladding of an optical fiber selectively. By stripping the cladding, these devices expose the core, allowing efficient coupling of the optical signal with other optical components.

How Do They Differ from Traditional Power Strippers?

Traditional power strippers remove both the cladding and part of the core, which can lead to higher signal loss. Cladding power strippers, on the other hand, maintain the integrity of the core while removing only the cladding, resulting in reduced signal loss and better overall performance.

Advantages of Cladding Power Strippers

Enhanced Signal Purity

Cladding power strippers enable the isolation of the core, reducing interference and enhancing signal purity. This results in improved data transmission with fewer errors.

Better Power Efficiency

By selectively removing the cladding, these strippers help manage power more efficiently, optimizing the network’s energy consumption and reducing operational costs.

Compatibility with Multiple Wavelengths

Cladding power strippers are designed to accommodate various wavelengths, making them suitable for use in networks with multiple signal channels.

Reduced Signal Loss

With their precise stripping capabilities, these power strippers minimize signal loss, ensuring that data travels through the network with minimal degradation.

Applications of Cladding Power Strippers

Telecommunications

In the telecommunications industry, cladding power strippers find applications in long-distance data transmission, enhancing signal quality in optical communication systems.

Data Centers

Cladding power strippers play a crucial role in data centers, where efficient power management and signal purity are essential for seamless data processing and storage.

Medical Imaging

The medical field benefits from the use of cladding power strippers in optical imaging systems, where signal clarity and accuracy are critical for accurate diagnoses.

Future Prospects and Innovations

Integration with AI and IoT

As AI and IoT technologies continue to advance, integrating cladding power strippers with smart systems can lead to more intelligent and automated network management.

Increasing Bandwidth Demands

The ever-growing demand for higher bandwidths necessitates the continuous development of more efficient optical components like cladding power strippers.

Advances in Manufacturing Techniques

Innovations in manufacturing processes can lead to more cost-effective and scalable cladding power stripper solutions, making them more accessible to a broader range of applications.

Challenges and Limitations

Cost Considerations

The initial investment in cladding power stripper may be higher compared to traditional alternatives, requiring careful cost-benefit analysis.

Standardization and Compatibility Issues

As with any emerging technology, standardization and compatibility across different systems remain challenges that need to be addressed for widespread adoption.

Maintenance and Reliability

Ensuring the long-term reliability of cladding power strippers requires proper maintenance and periodic assessment.

Conclusion

Cladding power strippers hold significant promise in revolutionizing fiber optic networks by improving signal quality, managing power efficiently, and catering to the demands of modern data communication. As technology continues to evolve, these innovative devices are expected to play an increasingly vital role in shaping the future of high-speed, reliable data transmission.

Advantages of cladding power stripper for high-power fiber laser system

Heat handling has been often a challenge for high power fiber lasers when the output power grows abruptly. But this is no longer a matter of concern, there is far better solution not just capable of handling health proficiently but also offering a thong of advantages. And this is none other than cladding power stripper which has magical capacity to deal with the unwanted optical power.

So the methods of stripping the unwanted light got much attention recently, and the thermal effect is now given much emphasis. Cladding power stripper uses microchannel sink –one of the most promising high efficiency heat exchange technologies, which improves the efficiency of heat exchange by sinking heat in CPS.

CPS is a component of the system used to remove unwanted light and distribute the heat converted by it. It is perfect for a system that transmits signal light in the core which absorbs inner cladding and all pumping light.

The cooling technology is implemented at the time designing of cladding power stripper structure. Header shaped microchannel provides better flow velocity uniformity than the trapezoidal and the triangular headers.

The CPS works better within a certain temperature. The temperature should not be more than 60 ◦C because of colloidal macromolecule substances in fiber. The idea temperature for cladding power stripper is 50.9 ◦C. CPS with microchannel heat sinking is sufficient for 10 kW DCFLSs.

So advantages of cladding power stripper can be summed up as:

it is ideal for 10 kW DCFLSs
It can work within as high temperature as 60 ◦C
It uses microchannel heat sink –one of the most efficient cooling technologies

However, the convective heat transfer coefficient depends on thermal conductivity and diameter of cooling liquid. For microchannel the diameter is 0.1–1 mm[8] , the convective heat transfer coefficient can be improved significantly. If convective heat transfer coefficient is replaced, the dissipated heat will increase, which means there will be more cooling.

To sum up

Given its super ability, along with other several benefits, to dispersing heat, CPS (cladding power striper) is hailed as the best for high power fiber lasers and a system that transmits signal light in the core where inner cladding and all pumping light. You can buy high quality cladding power stripper in China at the best price from a reputed dealer like DK Photonics, a leading name optical passive components.

Discussing Multiple Aspects of a Standard Cladding Power Stripper

Fiber laser systems have many advantages over other laser systems, including high beam quality, high conversion efficiency, cost-effectiveness, and lightweight. They have been widely applied in areas, such as optical sensing, medical devices, advanced industrial processing, and military defense. With the development of the double cladding fiber technology and laser diode pump technology, the output power of the fiber laser systems has been increased rapidly. However, the unwanted light and optical power increase, due to which the utilization of cladding power stripper becomes essential.

The actual and prime sources of the unwanted light transmitting in the cladding can be divided into 3 sections

Amplified spontaneous emission (ASE)

Residual pump light which is often there at the gain fiber’s end

Core light being reflected into the cladding or leaking into it

All the above-described unwanted light sources are actually spread throughout the chain of components. Excited gain medium naturally generates the amplified spontaneous emission. It is responsible for heavy watts of the entire unwanted light in any high-power laser setting, and actually more in an amplifier.

Performance Specifications

Parameters	Unit	Values
justify Signal Wavelength	nm	1030,1064,108,1550
Operating Wavelength-Pumps	nm	800~1200
Cladding attenuation(min)	dB	17~20
Type. Insertion Loss (at 25℃)	dB	0.05
Max. Insertion Loss (at 25℃)	dB	0.20
Min. Polarization Extinction Ratio	dB	18(For PM Fiber)
Cladding Power Handling(Stripping Power)	W	10, 20, 30,…
Fiber Type In/Out	/	Double Clad fiber
Pigtail Length	m	0.8 or other
Operation Temperature	℃	0 ~ +50
Storage Temperature Range	℃	-20 ~ +75

General Configuration for CPS:

1.5μm Fiber laser：

Working Wavelength(nm)	Input/ouput Fiber	Signal IL	Min.Stripping Efficiency	Max.Power Stripping
1530~1570	SM-GDF-1550	≤0.2dB	20dB	20W
1530~1570	12/130µm,NA0.20/0.46	≤0.2dB	20dB	50W
1530~1570	25/300µm,NA0.09/0.46	≤0.2dB	20dB	100W
1530~1570	PM-GDF-1550	≤0.2dB/ER>18dB	20dB	20W
1530~1570	PM 12/130µm,NA0.20/0.46	≤0.2dB/ER>18dB	20dB	50W
1530~1570	PM 25/300µm,NA0.09/0.46	≤0.2dB/ER>18dB	20dB	100W

2.0μm Fiber laser：

Working Wavelength(nm)	Input/ouput Fiber	Signal IL	Min.Stripping Efficiency	Max.Power Stripping
1950~2050	10/130µm,NA0.15/0.46	≤0.2dB	20dB	20W
1950~2050	25/250µm,NA0.09/0.46	≤0.2dB	20dB	100W
1950~2050	25/400µm,NA0.09/0.46	≤0.2dB	20dB	100W
1950~2050	PM10/130µm,NA0.15/0.46	≤0.2dB/ER>18dB	20dB	20W
1950~2050	PM25/250µm,NA0.09/0.46	≤0.2dB/ER>18dB	20dB	50W

Now if I talk about its availability in the market. There are several suppliers who can provide you with CPS (cladding power stripper) in all types. In case, you don’t find a standard CPS to fulfill your requirements, manufacturers generally accept the customization of a specially needed CPS or a set of them. You would be able to choose solicitations for specific fiber type, various wavelengths, and the handling power of operations as per your particular requirements.

If you need to buy these power strippers, you may search through the web to find various manufacturers and suppliers. You can simply search for the same, compare their specifications, select the quantity, and place the order as per your need.

Functions of a Cladding Power Stripper and Its Market

The configuration of a particular DCFLS (double cladding fiber laser system) is generally schematically arranged. The fiber is cladding-pumped by high power diode stacks which then spread and amplify the pump light. High reflector and output coupler fiber Bragg gratings are usually etched on the fiber. It is best for a system that has all light signals transmit in the core and inner cladding where all pumping light is core-absorbed.

But, there always some unwanted light exists in reality. CPS, also known as cladding power stripper is an important component of the fiber optic systems which is used to remove this typical unwanted light and distribute the heat, initiated by that unwanted light.

The unwanted light spreading all over the cladding actually consists of the main three parts mentioned below.

Ampliﬁed spontaneous emission (ASE)

Residual pump light at the gain ﬁber’s end

Core light getting leaked or reflected inside the cladding

Prior to the output of light, the unwanted light has to be eliminated so that it would use unused space optics of a complicated laser system. The unwanted light gets converted into heat and this heat may lead to heated up optics and the core light would not be able to focus nicely. Moreover, the heat may also burn or damage the system’s important components or deteriorate the function when multiple systems are combined together for greater efficiency.

In double cladding fiber laser systems, the unwanted optical power and light must be reduced so that the output light gains higher beam quality. Several kinds of research have been done to strip that light from the cladding. Removing the originally there fluoroacrylate jacket and coating the fiber with a high index polymer can literally strip residual light of more than a hundred watts. Fabrication using a suitable etching method successfully cleared the test and stated that it offers good behavior instability so that it can be used in the applications with higher power laser systems.

All such researches successfully eliminated the unwanted light and the crucial work after that light gets converted into heat. Some of the researches also provided a cooling method of their tests, including cooling water based plate and air cooling. But because the output power of DCFLS increases, the traditionally used cooling methods could not stand the harsh heat.

Apart from there functions, there are manufacturers who can provide you with cladding power stripper of all kind of double Clad fiber where cladding power can reach up to 500W. If you couldn’t find a standard CPS that fulfills your needs, you can provide your desired specification to a reliable manufacturer and get a quote for a custom CPS. Requests for custom fiber type, operation handling power operation, varying wavelengths, and other specific requirements will be addressed quickly.

All about the Cladding Power Stripper and Its Market

The multimode optical power stripper, commonly known as cladding power stripper is designed for applications like high power fiber lasers and amplifiers. The device is ideally used to strip ASE, residual pump power, and escaped core modes double cladding’s inner layer while it preserves minimal degradation of beam quality and signal power. The signal power reflected into the inner cladding can be stripped out also.

The cladding power stripper is mainly utilized in high-power fiber lasers and amplifiers that require efficiency to handle substantial optical powers. It requires making sure that the powers are sufficiently absorbed in a widespread area and the heat that is generated can be removed easily without damaging the surrounding pars, for instance, the mode stripper.

In fiber laser systems, the pump energy and doped fiber are generally absorbed which then transformed into signal energy. Here, the pump cannot be entirely absorbed, the residual part of the outer cladding is not required and it is even dangerous for downstream components. The CPS here can efficiently strip off the residual pump and signal that are transmitted back in clad and at the same time, it can keep the amplified signals protected.

Several manufacturers today provide cladding power strippers with power up to 300W and all kind of double clad fiber. In case you don’t find a standard CPS that meets your requirements, you may contact a few manufacturers as many of them would welcome you to put your demands on the table and they will give you a quote as per the custom specifications that are given by you. Some of them also accept requests for different wavelengths, application handling power, custom fiber type, and other specifically essential requirements.

Some of the key features of the CPS

Low Insertion Loss
High Power Absorption
High Power Handling
Fiber can be customized
High Reliability
PM and Non-PM are available
RoHS compliant
Excellent Temperature Stability

Following are some of the most common applications of these cladding power strippers where the specifications of the strippers may be different.

Fiber amplifier and laser systems
Industrial, Biomedical, Telecom,
ASE stripping
Life Science, Imaging, Quantum optics
The cladding-mode-free high power beam delivery
Metrology

When it comes to finding a reliable manufacturer and supplier, you can put your trust in that one that promises to deliver quality and durable electronic products and actually delivers the same when you place an order.

Today majorly all such manufacturers sell these products online too, in fact, the online market of these electronic components is growing rapidly. It helps us to connect to manufacturers, suppliers, and sellers sitting in different parts of the country. While choosing one, you must consider the product description and specifications. However, it is also advised to consider checking the reviews and ratings of the manufacturer before placing the order.

Learning the Different Coating Stripping Methods

The cladding power stripper also referred to as the multimode optical power stripper is designed for amplifier applications and high power fiber laser. It is an ideal device for ASE, residual pump power stripping, core modes that have escaped from double cladding fibers inner cladding while ensuring preservation of single power minimal degradation and beam quality (M2). Single power that is reflected into the inner cladding may also be stripped out too. The handling capability of the stripping power goes to 800W or at times may be even higher

Stripping the Coating

The fibers that most reputable companies supply all come with a standard acrylate single layer coating or, in some such as the high power products, a coating that is high temperature enduring. In comparison to dual layer coatings, the coatings that are single layer are more brittle and smooth. The coating can be removed readily using the conventional tools for fiber stripping such as the Fitel S-210 Clauss or CFS-1 for 125 μm cladding diameter fiber or for larger cladding diameters the Clauss No Nik stripper is used. For fibers whose outer diameter is non-standard, it is recommended that an adjustable stripper is used. Thermal strippers such as those that are attached to the Schleuniger FiberStrip 7030 or the Vytran FFS-2000 can be used for all fiber in a safe way.

Alternatively, chemical stripping of fibers can be done using an appropriate solvent. For example, the coating can be exposed for one minute to sulfuric acid at 120°C sulfuric acid. Before the fiber is dipped into the liquid, the tip should be sealed with a drop of glue of 2 mm in diameter or through the end fiber hole collapsing using a fusion splicer. It is worth noting that most glue types are dissolved in this acid, but epoxies that are two-component such as the Epotek ND353 tends to dissolve in a slower manner than the coating.

It is also possible to obtain chemical stripping through application on the fiber tip, of paint stripper. The paint stripper is usually in the form of a gel so as to reduce the occurrence of out-gassing and can be applied easily using a small brush. After a minute or so, the coating becomes soft and is removed easily using a lens tissue. It is worth noting that paint stripper typically contains dichloromethane (CH2Cl2) and as such there may be restrictions by local regulations to use it. For lower quality and faster stripping, another option would be to use a normal cigarette lighter to burn the coating off. However, the fiber may end up becoming brittle hence not the best choice for stripping.

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

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.

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.

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

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.

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

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.

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

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)

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)

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)

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.

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