Doped Fibers

[SAHIL SINGH]

Can anyone please provide information about double clad doped fibers ? Also i want to know whether we can simulate double clad dopedd fibers in optiwave system ?

[FAYIQA NAQSHBANDI]

HELLO SAHIL SINGH..

Are you using optisystem or optifiber for your design.. I am not sure if it possible in optisystem.. Still see if someone knows about it.

Thanks & regards

[aasif bashir dar]

hi sahil singh,
for simulating double clad dopedd fibers in optiwave system, you require device level software of the optwave namely optifiber..i suggest you to browse and know little bit about that software.

with regards

[SAHIL SINGH]

Hi Fayiqa Naqshbandhi,

I am using optisystem for my design.. Please if anyone can provide information..

Regards
Sahil Singh

[FAYIQA NAQSHBANDI]

HELLO SAHIL SINGH..

You must go through the tutorial of the opti-fiber tool..it will provide you with an option to design double clad fiber…The “Material Properties” allows the user to specify the Sellmeier and nonlinear coefficients of the fiber material. It also displays the material refr. index as a function of wavelength. For the dispersion model it is assumed that the fiber profile consists of regions with only the host material and doped regions. One of the dopants rises the refractive index, while the other dopant lowers it…Please try going through the optifiber tute..I hope it will, be of some help..

Thanks & regards

[SAHIL SINGH]

Hi Aasif Bashir,

Thanks for your reply.. I will try to search for the optifiber..

Regards
Sahil Singh

[aasif bashir dar]

here the link for opti fiber basics

Fiber Profile

with regards

[SAHIL SINGH]

Hi Fayiqa Naqshbandhi,

Indeed i will try to look into the tutorial of the opti-fiber tool…. Thanks for your response.. Your eforts are highly appreciated..

Regards
Sahil Singh

[aasif bashir dar]

hi sahil singh,

there is the provision to chnage materials properties in the optifiber.The “Material Properties” allows the user to specify the Sellmeier and nonlinear coefficients of the fiber material. It also displays the material refr. index as a function of wavelength. For the dispersion model it is assumed that the fiber profile consists of regions with only the host material and doped regions. One of the dopants rises the refractive index, while the other dopant lowers it

the sellmier equation is most widely accepted equation for evaluating the material dispersion in the optical materials

with regards

[ZULKARNAIN]

hi sahil singh…
Double-clad fibers is indeed a very important technology in the area of active fiber optics, particularly for amplifiers and high-power fiber lasers.It allows cladding pumping of fiber devices. Here, the laser light propagates in a single-mode (or multimode) core, which is surrounded by an inner cladding in which the pump light propagates. Only the core (or sometimes a ring around the core) is rare-earth-doped. The pump light is restricted to the inner cladding by an outer cladding with lower refractive index, and also partly propagates in the single-mode core, where it can be absorbed by the laser-active ions. The inner cladding has a significantly larger area (compared with that of the core) and typically a much higher numerical aperture, so that it can support a large number of propagation modes, allowing the efficient launch of the output, e.g. of high-power laser diodes (e.g. beam-shaped high-power diode bars), despite their poor beam quality.
with regards

[ZULKARNAIN]

sorry i forgot to attach the link for the above post.So i am attaching the link for your reference.Hope it may help you.
https://www.rp-photonics.com/double_clad_fibers.html
Also for simulating double clad doped fibers in optiwave system, i agree with Aasif Bashir Dar and Fayiqa Naqshbandhi that you will require device level software of the optiwave namely optifiber. So you should first try to understand the basics of the software and try to implement your design in that software.
Hope it may help you.
with regards.

[SAHIL SINGH]

Hi Zulkarnain,

Indeed i agree with your view that Double-clad fiber is a very important technology in the area of active fiber optics… I will try to look into the link which you have posted.. Thanks for your efforts

Regards
Sahil Singh

[ZULKARNAIN]

hi sahil…
you are welcome and i hope that your query is solved.
with regards..

[aasif bashir dar]

HI SAHIL SINGLE…
DOUBLE CALD , TRIPLE CLAD OR EVEN HIGHER ORDER CLADDS ARE CURRENTLY BEING USING MOSTLY FOR THE DISPERSION COMPENSATING FIBERS AND IS very important technology in the area of fiber optics…

WITH REGARDS

[Aabid Baba]

Hello Aasif,
I want to ask you if designing these fibers is possible in optisystem.

[SAHIL SINGH]

Hi Asif Bashir,

Its Sahil Singh.. Also thanks for providing the information of various higher order clad fibers..

Regards

Sahil Singh

[Aabid Baba]

Hello Sahil Singh,
Undoubtedly Double-clad fiber technology is indeed a very important technology in the area of active fiber optics as very well mentioned by other forum members. But as far as design is concerned , i agree with fayiqa naqshbandi and aasif bashir that you need to use all together a different tool for your requirement which is Opti-Fiber. Can you tell us what exactly are you using these fibers for for your system design..?
It would help us to understand the implications of these fibers.
Regards

[FAYIQA NAQSHBANDI]

HELLO..

Double-clad fibers are an important technology in the area of active fiber optics, particularly for high-power fiber lasers and
amplifiers.There are a variety of different designs of double-clad fibers.The simplest kind of design has a circular pump cladding and
a centered core . This is relatively easy to make and use, but in this kind of fibers there are propagation modes of the inner cladding
(related to helical rays) which have hardly any overlap with the core, so that some significant part of the pump light exhibits incomplete absorption. As a result, the gain and power efficiency are compromised
Thanks & regards

[umer syed]

hi sahil singh
Double-clad fibers are an important technology in the area of active fiber optics, particularly for high-power fiber lasers and
amplifiers.There are a variety of different designs of double-clad fibers.The simplest kind of design has a circular pump cladding and
a centered core . This is relatively easy to make and use, but in this kind of fibers there are propagation modes of the inner cladding
(related to helical rays) which have hardly any overlap with the core, so that some significant part of the pump light exhibits incomplete absorption. As a result, the gain and power efficiency are compromised. To a limited extent, this problem can be solved by strongly coiling
the fiber.Double-clad fibers can also be made as photonic crystal fibers . Here, the multi mode pump core is suspended by very thin struts
in the air cladding, through which the pump light cannot escape. Such a structure can have a very high numerical aperture of at least 0.6 for the pump light; this further reduces the requirements concerning the brightness of the pump source. The thickness of the struts can be chosen such that at the same time one achieves good mechanical stability, high thermal conductivity, and minimal pump losses. Another advantage
of this type of fiber is that pump light is kept away from the protective polymer coating, avoiding any damage by absorbed pump light. The guidance of the core is achieved as in other photonic crystal fibers.
Also for simulating double clad doped fibers in optiwave system, i agree with asif bashir darthat you will require device level software of the optiwave namely optifiber. So you should first try to understand the basics of the software and try to implement your design in that software.
with regards

[SAHIL SINGH]

Hi Umer Syed,

Thanks for providing the information… Indeed your efforts appreciated.. I am looking into the basics of the optifiber as already suggested by other members on the forum..

Regards
Sahil Singh

[aasif bashir dar]

hi sahil singh…

sory regard the name error previously… and you are welcome

with regards

[SAHIL SINGH]

Hi Asif Bashir,

Not an issue at all.. No need for sorry..

Regards
Sahil Singh

[Ranjeet Kumar]

Hi,
Double-clad fiber (DCF) is a class of optical fiber with a structure consisting of three layers of optical material instead of the usual two. The inner-most layer is called the core. It is surrounded by the inner cladding, which is surrounded by the outer cladding. The three layers are made of materials with different refractive indices.
Here, the laser light propagates in a single-mode (or multimode) core, which is surrounded by an inner cladding in which the pump light propagates. Only the core (or sometimes a ring around the core) is rare-earth-doped. The pump light is restricted to the inner cladding by an outer cladding with lower refractive index, and also partly propagates in the single-mode core, where it can be absorbed by the laser-active ions. The inner cladding has a significantly larger area (compared with that of the core) and typically a much higher numerical aperture, so that it can support a large number of propagation modes, allowing the efficient launch of the output, e.g. of high-power laser diodes (e.g. beam-shaped high-power diode bars), despite their poor beam quality.

[Ranjeet Kumar]

Hi Sahil,
The applications of double clad doped fibers are:

Double-clad fibers are extensively used for cladding-pumped high-power fiber lasers and amplifiers. Such devices can have a fairly high power conversion efficiency (sometimes above 80%) combined with a high beam quality. As the beam quality of the output can be diffraction-limited whereas that of the pump can be poor, the brightness of the laser or amplifier output can be much higher than that of the pump source. Particularly if this increase in brightness is essential for an application, the cladding-pumped fiber laser may be called a brightness converter.

[Ranjeet Kumar]

Hi sahil,
Fianlly i would like to share the Typical Problems with Double-clad Fibers
It has already been mentioned above that rather incomplete pump absorption can result from cladding modes with weak core overlap. Even if strong mode mixing is ensured with a suitable design, the pump absorption is reduced according to the limited overlap of pump light with the doped fiber core. Therefore, one typically requires an accordingly longer length of active fiber. That can be detrimental e.g. in terms of fiber nonlinearities. Also, the larger total amount of dopant ions can make it more difficult to achieve laser or amplifier operation with short signal wavelengths, and the increased amount of fluorescent light can decrease the power conversion efficiency.

Some of the signal light may be coupled out of the core into the pump cladding, e.g. as a result of bending or by a fiber Bragg grating. That light will then remain in the pump cladding and will not (as for other fibers) get lost via the coating. One may need some type of cladding light stripper (cladding mode stripper) to remove such light, if it would be disturbing in the device output. That may also be the case for residual pump light.

[Ubaid Bhat]

hi ranjeet kumar..
i agree with in saying that ome of the signal light may be coupled out of the core into the pump cladding, e.g. as a result of bending or by a fiber Bragg grating. That light will then remain in the pump cladding and will not (as for other fibers) get lost via the coating.
but you have mentioned active fiber in your comment.can you explain please this active fiber related to double clad fibers.
with regards
ubaid bhat

[SAHIL SINGH]

Hi Ranjeet,

Thanks for providing such a detailed explanation about the double clad doped fibers.. Your efforts are indeed highly appreciated.. You are one of the most active members on this forum.. Keep doing the good work..

Regards
Sahil Singh

[SAHIL SINGH]

Hi Ubaid Bhat,

Nice to hear from you… I allready got the answer i was looking for anyways i would like to thank you for your concern and willingness to help in resolving my query…

Regards
Sahil Singh

[Ranjeet Kumar]

You are most welcome sahil singh.
It was a new term to me , i am really happy to get information about that.
I will try to update more information related to it.
I think it is related to latest research in the fields of optical fiber.

[SAHIL SINGH]

Hi Ranjeet Singh,

Well i too think that it is related to the latest research in optical fibers… Glad to know that you provided the information…. Keep up your efforts

Regards
Sahil Singh

[Manoj Kumar]

hi burhan mina llah,

i think when we post a probem in the optiwave forum, there is provision for selecting the question type
KNOWLEDGE
Contains a detailed Q&A knowledge base.
GENERAL
All non-technical questions.
SYSTEM
Optical system design and analysis.
SPICE
Opto-electronic circuit design.
FDTD
Finite-Difference Time-Domain simulation.
BPM
Beam Propagation Method analysis and design.
GRATING
Fiber optic grating simulation.
FIBER
Optical fiber design and characterization.

i think in knowledge and in genneral category ,any non technical persion can ask question for the information perposes and rest of options can be used in case of the user having query related to the software ..and its working..

with regards

[Manoj Kumar]

hi sahil singh
Double-clad fibers are an important technology in the area of active fiber optics, particularly for high-power fiber lasers and
amplifiers.There are a variety of different designs of double-clad fibers.The simplest kind of design has a circular pump cladding and
a centered core . This is relatively easy to make and use, but in this kind of fibers there are propagation modes of the inner cladding
(related to helical rays) which have hardly any overlap with the core, so that some significant part of the pump light exhibits incomplete absorption. As a result, the gain and power efficiency are compromised. To a limited extent, this problem can be solved by strongly coiling
the fiber.Double-clad fibers can also be made as photonic crystal fibers . Here, the multi mode pump core is suspended by very thin struts
in the air cladding, through which the pump light cannot escape. Such a structure can have a very high numerical aperture of at least 0.6 for the pump light; this further reduces the requirements concerning the brightness of the pump source. The thickness of the struts can be chosen such that at the same time one achieves good mechanical stability, high thermal conductivity, and minimal pump losses. Another advantage
of this type of fiber is that pump light is kept away from the protective polymer coating, avoiding any damage by absorbed pump light. The guidance of the core is achieved as in other photonic crystal fibers.
Also for simulating double clad doped fibers in optiwave system, i agree with asif bashir darthat you will require device level software of the optiwave namely optifiber. So you should first try to understand the basics of the software and try to implement your design in that software.
with regards

[Manoj Kumar]

Double-clad fibers is indeed a very important technology in the area of active fiber optics, particularly for amplifiers and high-power fiber lasers.It allows cladding pumping of fiber devices. Here, the laser light propagates in a single-mode (or multimode) core, which is surrounded by an inner cladding in which the pump light propagates. Only the core (or sometimes a ring around the core) is rare-earth-doped. The pump light is restricted to the inner cladding by an outer cladding with lower refractive index, and also partly propagates in the single-mode core, where it can be absorbed by the laser-active ions. The inner cladding has a significantly larger area (compared with that of the core) and typically a much higher numerical aperture, so that it can support a large number of propagation modes, allowing the efficient launch of the output, e.g. of high-power laser diodes (e.g. beam-shaped high-power diode bars), despite their poor beam quality.
with regards

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