By purposefully causing consistent
birefringence over the whole fiber length, a polarization maintaining fiber (PM Fiber, PMF) maintains two polarization modes and prevents
random power coupling between them.
Integrating stress factors into the
fiber cladding causes the symmetry of polarization-maintaining single-mode
fibers (PM fibers) to be disrupted. The light is thus directed along the fast
and slow axes, two perpendicular principal states of polarization with distinct
propagation constants. Light linked into one of these axes maintains its linear
polarization. Because it is less sensitive to fiber bending, the linearly
polarized laser light is often linked to the slow axis.
The polarization that results when
light is connected into both axes is elliptical (if the coherence length of the
source is larger than the phase difference). But this arbitrary elliptical
state is altered by changes in strain and temperature.
A unique variety of single-mode
fiber is called polarization-maintaining fiber (PM Fiber). Randomly polarized
light can be transmitted using standard single-mode fibers. However, only one
polarization of the incoming light may be propagated via PM fiber. You can
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When light waves that are linearly
polarized are launched into a fiber that maintains polarization, there is
little to no cross-coupling of optical power between the polarization modes.
Some fiber optic parts, such as external modulators, which need polarized light
input, depend heavily on this polarization-keeping property.
By applying stresses to the
material itself, this property is obtained throughout the production process.
Both linear polarization maintaining fiber (LPMF) and circular polarization
maintaining fiber (CPMF) are types of polarization maintaining fiber (PMF).
Polarization maintaining fiber
applications
- PM optical fibers are utilized in
specialized applications including slab dielectric waveguides,
interferometry, and fiber optic sensors.
- In coherent optical transmission systems or
long-distance bidirectional optical transmission systems, PM fibers are
anticipated to be employed.
- They may also be utilized in transmission
applications where the polarization plane of the optical signal is
significant, such as coupling for optical-electrical integrated circuits
and transmission lines for optical sensors.
To preserve the polarization of the
incoming light and minimize cross-coupling between polarization modes, PM
fibers are employed in lithium niobate modulators, optical switch, Raman
amplifiers, and other polarization-sensitive devices.
