The difference between polymer light guide and polarization maintaining fiber

Polymer light guide
According to the material, there are inorganic optical fibers and polymer optical fibers, and the former is widely used in industry. Inorganic optical fiber materials are divided into two categories: single-component and multi-component. The single component is quartz, and the main raw materials are silicon tetrachloride, phosphorus oxychloride and boron tribromide. Its purity requires that the impurity content of transition metal ions such as copper, iron, cobalt, nickel, manganese, chromium, and vanadium is less than 10ppb. In addition to this, OH ions are required to be less than 10ppb. Quartz fiber has been widely used. There are many multi-component raw materials, mainly silicon dioxide, boron trioxide, sodium nitrate, thallium oxide, etc. This material is not yet widespread. The polymer optical fiber is an optical fiber made of transparent polymer, which is composed of a fiber core material and a sheath material. The core material is a fiber made of high-purity and light-transmitting polymethyl methacrylate or polystyrene spinning, and the outer layer is a fluorine-containing polymer or an organic silicon polymer.
The optical loss of polymer optical fibers is relatively high. In 1982, Nippon Telegraph and Telegraph Corporation used deuterated methyl methacrylate polymer wire as the core material, and the optical loss rate was reduced to 20dB/km. However, the characteristics of polymer optical fiber are that it can make optical fiber with large size and large numerical aperture. However, the optical loss is large and can only be used in short distances. An optical fiber with an optical loss of 10 to 100 dB/km can transmit hundreds of meters.

PM Fiber
Polarization-maintaining fiber: Polarization-maintaining fiber transmits linearly polarized light, and is widely used in various fields of the national economy such as aerospace, aviation, navigation, industrial manufacturing technology and communications. In the interferometric fiber optic sensor based on optical coherence detection, the use of polarization-maintaining fiber can ensure that the linear polarization direction remains unchanged, improve the coherent signal-to-noise ratio, and achieve high-precision measurement of physical quantities. As a special type of optical fiber, polarization-maintaining fiber is mainly used in sensors such as fiber optic gyroscopes, fiber optic hydrophones, and fiber optic communication systems such as DWDM and EDFA. Since fiber-optic gyroscopes and fiber-optic hydrophones can be used for military inertial navigation and sonar, they are new technology products, and polarization-maintaining fibers are their core components. Therefore, polarization-maintaining fibers have always been included in the list of embargoes against China by western developed countries. During the drawing process of the polarization-maintaining fiber, the polarization-maintaining performance will be degraded 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 perpendicular to it. characteristic axis, resulting in a decrease in the polarization extinction ratio of the outgoing polarized light signal. This defect is the effect of birefringence in the fiber. In polarization-maintaining fibers, the stronger the birefringence effect, the shorter the wavelength, and the better the polarization state of the transmitted light is maintained.