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Polarization-maintaining Fibers

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25 suppliers for polarization-maintaining fibers are listed.

Among them:

NKT Photonics

several types of broadband (UV–nIR) single-mode PM fibers with large mode area. Also available with collimators and alignment mechanics as complete fiber delivery solutions.

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Ask RP Photonics for advice on different types of fibers and their use in fiber-optic devices.

Acronym: PM fiber

Definition: specialty optical fibers with strong built-in birefringence, preserving the properly oriented linear polarization of an input beam

German: polarisationserhaltende Fasern

Category: fiber optics and waveguides

How to cite the article; suggest additional literature

Optical fibers always exhibit some degree of birefringence, even if they have a circularly symmetric design, because in practice there is always some amount of mechanical stress or other effect which breaks the symmetry. As a consequence, the polarization of light propagating in the fiber gradually changes in an uncontrolled (and wavelength-dependent) way, which also depends on any bending of the fiber and on its temperature.

Principle of Polarization-maintaining Fibers

The mentioned problem can be fixed by using a polarization-maintaining fiber, which is not a fiber without birefringence, but on the contrary a specialty fiber with a strong built-in birefringence (high-birefringence fiber or HIBI fiber, PM fiber). Provided that the polarization of light launched into the fiber is aligned with one of the birefringent axes, this polarization state will be preserved even if the fiber is bent. The physical principle behind this can be understood in terms of coherent mode coupling. The propagation constants of the two polarization modes are different due to the strong birefringence, so that the relative phase of such copropagating modes rapidly drifts away. Therefore, any disturbance along the fiber can effectively couple both modes only if it has a significant spatial Fourier component with a wavenumber which matches the difference of the propagation constants of the two polarization modes. If this difference is large enough, the usual disturbances in the fiber are too slowly varying to do effective mode coupling.

Ways of Realizing Polarization-maintaining Fibers

A commonly used method for introducing strong birefringence is to include two (not necessarily cylindrical) stress rods of a modified glass composition (with a different degree of thermal expansion) in the preform on opposite sides of the core (Figure 1). When a fiber is drawn from such a preform, the stress elements cause some mechanical stress with a well-defined orientation. Another variant of that approach is to have an elliptical cladding of different glass around the core.

polarization-maintaining fibers

Figure 1: Polarization-maintaining PANDA fiber (left) and bow-tie fiber (right). The built-in stress elements, made from a different type of glass, are shown with a darker gray tone.

Another technique is to use an elliptical core causing so-called form birefringence [1]. Here, the elliptical form itself, even without any mechanical stress, produces some level of form birefringence.

In a photonic crystal fiber (PCF), very strong birefringence can be obtained with an asymmetric arrangement of air holes, but stress elements (which may be index-matched) can also be used [6]. In any case, the birefringent beat length can be so small (a few millimeters or even less) that additional stress effects can cause only a low level of mixing of the polarization states. The index contrast can be several times 10−3, whereas in all-glass PM fibers it is typically only a few times 10−4.


Polarization-maintaining fibers are applied in devices where the polarization state cannot be allowed to drift, e.g. as a result of temperature changes. Examples are fiber interferometers and certain fiber lasers. A disadvantage of using such fibers is that usually an exact alignment of the polarization direction is required, which makes production more cumbersome. Also, propagation losses are higher than for standard fiber, and not all kinds of fibers are easily obtained in polarization-preserving form.

The polarization extinction ratio of light coming out of a polarization-maintaining fiber may be lower than that at the fiber input. This can occur as a result of imperfect alignment of the polarization direction at the input, but also be due to some residual degree of mode mixing. The latter effect can be strongly increased by mechanical stress (e.g. in a fiber connector). For applications requiring a very high polarization extinction ratio (e.g. in interferometry), it can be necessary to use an additional high-quality polarizer after the fiber.

Polarization-maintaining fibers should not be confused with single-polarization fibers, which can guide only light with a certain linear polarization.


[1]K. Sano and Y. Fuji, “Polarization transmission characteristics of optical fibers with elliptical cross section”, Electron. Commun. Jpn. 63, 87 (1980)
[2]A. Kumar et al., “Birefringence calculations in elliptical-core optical fibers”, Electron. Lett. 20, 112 (1984)
[3]J. Noda et al., “Polarization-maintaining fibers and their applications”, J. Lightwave Technol. 4 (8), 1071 (1986)
[4]D. Mogilevtsev et al., “Design of polarization-preserving photonic crystal fibres with elliptical pores”, J. Opt. A: Pure Appl. Opt. 3, S141 (2001)
[5]J. R. Folkenberg et al., “Polarization maintaining large mode area photonic crystal fiber”, Opt. Express 12 (5), 956 (2004)
[6]T. Schreiber et al., “Stress-induced single-polarization single-transverse mode photonic crystal fiber with low nonlinearity”, Opt. Express 13 (19), 7621 (2005)

(Suggest additional literature!)

See also: fibers, single-polarization fibers, single-mode fibers, photonic crystal fibers, birefringence, polarization of laser emission, specialty fibers, mode coupling, fiber polarization controllers, Spotlight article 2007-05-19

Dr. R. Paschotta

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RP Fiber Power – the versatile Fiber Optics Software

An Amazing Tool

RP Fiber Power software

This amazing tool is extremely helpful for the development of passive and active fiber devices.


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Single-mode and Multi­mode Fibers


Calculate mode properties such as

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  • effective mode area
  • effective index
  • group delay and chromatic dispersion

Also calculate fiber coupling efficiencies; simulate effects of bending, nonlinear self-focusing or gain guiding on beam propagation, higher-order soliton propagation, etc.

Arbitrary Index Profiles

A fiber's index profile may be more complicated than just a circle:

special fibers

Here, we "printed" some letters, translated this into an index profile and initial optical field, propagated the light over some distance and plotted the output field – all automated with a little script code.

Fiber Couplers, Double-clad Fibers, Multicore Fibers, …

fiber devices

Simulate pump absorption in double-clad fibers, study beam propagation in fiber couplers, light propagation in tapered fibers, analyze the impact of bending, cross-saturation effects in amplifiers, leaky modes, etc.

Fiber Amplifiers

fiber amplifier

For example, calculate

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in single amplifier stages or in multi-stage amplifier systems, with double-clad fibers, etc.

Fiber-optic Telecom Systems

eye diagram

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fiber laser

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fiber laser

For example, study

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… and even Bulk Devices

regenerative amplifier

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Mode Solver

fiber modes

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Beam Propagation

beam propagation

Propagate optical field with arbitrary wavefronts through fibers. These may be asymmetric, bent, tapered, exhibit random disturbances, etc.

See our demo video for numerical beam propagation.

Laser-active Ions

level scheme

Work with the standard gain model, or define your own level scheme!

Can include different ions, energy transfers, upconversion and quenching effects, complicated pumping schemes, etc.

Multiple Pump and Signal Waves, ASE

optical channels

Define multiple pump and signal waves and many ASE channels – each one with its own transverse intensity profile, loss coefficient etc.

The power calculations are highly efficient and reliable.

Simple Use and High Flexibility Combined

For simpler tasks, use convenient forms:

signal parameters

Script code is automatically generated and can then be modified by the user. A powerful script language gives you an unparalleled flexibility!

High-quality Documentation and Competent Support

The carefully prepared comprehensive documentation includes a PDF manual and an interactive online help system.

Competent technical support is provided: the developer himself will help you and make sure that any problem is solved!

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