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What is the Polarization-maintaining fibers?

What is the Polarization-maintaining fibers?

Feb 19, 2021

Generally speaking: Polarization-maintaining fibers is to use special materials to weaken the crystal birefringence effect in the fiber to ensure that the degree of polarization of the incident light remains unchanged for a long time; Polarization-retaining fiber is a kind of fiber whose polarization state remains almost constant for a long time when the polarized light is transmitted in the fiber.


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Detailed said:

Polarized optical fiber: Polarized optical fiber transmission line, widely used in aerospace, aviation, navigation, industrial manufacturing technology and communication and other fields of the national economy. In the interferometric fiber sensor based on optical coherence detection, the polarization-maintaining fiber can keep the linear polarization direction unchanged and improve the coherent signal-to-noise ratio, so as to realize the high precision measurement of the physical quantity. As a kind of special fiber, polarization-maintaining fiber is mainly used in fiber gyroscopes, fiber hydrophone and optical fiber communication systems such as DWDM and EDFA. Fiber optic gyroscope and fiber optic hydrophone, which can be used in military inertial navigation and sonar, are high-tech products, and polarization-maintaining fiber is its core component. Therefore, polarization-maintaining optical fiber has been included in the list of embargoes on China by western developed countries.


During the drawing process of polarized fiber, the polarization keeping performance will decline due to the structural defects inside the fiber, that is, when the linearly polarized light is transmitted along one characteristic axis of the fiber, part of the optical signal will be coupled into another characteristic axis perpendicular to it, and finally the polarization extinction ratio of the output polarized light signal will decline. In polarisation-maintaining fiber, the weaker the birefringence effect is, the shorter the wavelength of light is and the better the polarization of transmitted light can be maintained.


Even if an ordinary optical fiber is made symmetrical, it will be asymmetrical and birefringent due to mechanical stress in practical applications, so the polarization of light will change irregularly as it travels through an ordinary optical fiber. The main influencing factors are wavelength, curvature, temperature and so on.


Polarization maintaining fiber can solve the problem of polarization state change, but it can not eliminate the birefringence phenomenon in the fiber, but through the design of the fiber geometry size, produce stronger birefringence effect, to eliminate the influence of stress on the polarization state of the incident light.


Therefore, polarized fiber is generally used in applications sensitive to polarization state, such as interferometers, or lasers, or in the connection between the light source and the external modulator, etc.

 

Elite Optoelectronics provides high-quality  Polarization-maintaining fibers laser diode modules with ultra-narrow linewidth covering the wavelength range of 375 nm-980 nm. For more, please contact us at 86-29-68590616 or sale@s-laser.com