A research team at the Optonics Research Center at the University of Southampton has produced an optical fiber whose light propagation time does not change with temperature in this fiber (Optica, doi: 10.1364 / OPTICA.4.000659). The team employs a clever design that increases the group velocity of light in an optical fiber by precisely offsetting the elongation of the fiber at high temperatures and the thermal index change of the fiber. The results demonstrate that this is an optical fiber with a thermal delay coefficient (TCD) equal to zero and has potential advantages in applications where time signals in optical fibers are required to be accurate, such as metrology and other applications. Using Hollow Photonic Bandgap Design to Balance Thermal Induced Length Variation Temperature-dependent changes in refractive index (and hence at light population speeds) researchers at the University of Southampton have produced an optical fiber in which the propagation time of light in the optical fiber is not affected by the optical fiber Effect of temperature. Image courtesy of Gregory Jasion, University of Southampton Change from glass material to air medium For every 1 ° C temperature change, the propagation time of an optical signal passing through one kilometer of a standard solid-core fiber changes by about 40 ps. In some areas, such as sensing applications, this temperature sensitivity in optical fiber is a practical property, not a flaw. However, it can not possibly cause damage to other applications that depend on accurate time signals, such as connecting an optical clock network across the mainland, the industry's simultaneous robotics in the Internet of Things, and precision lasers that stabilize anti-low frequency noise using fiber-optic delay lines. Fiber optic researchers have studied many ways to reduce the temperature sensitivity of fiber propagation time. One approach is to coat the fiber with a special coating to help offset the change in its refractive index with temperature. According to a new study, the best result of this is to reduce the thermal sensitivity of standard telecom fiber to 3.7 ps / km / K. The same Southampton research team in charge of the new Optica study pointed to an alternative approach of replacing solid silica glass fibers with hollow photonic band gap fiber designs, where most of the optical power passes through the air medium instead of the glass material. Since approximately 95% of the fiber propagation time's sensitivity to the thermo-optic effect of silica varies with temperature, it has been reported that this change has been reported to reduce the propagation time sensitivity to 2 ps / km / K. Thermal effect compensation To reduce from 2 ps / km / K sensitivity above, the Southampton R & D team has a detailed understanding of the parameters that determine the propagation time of light within the fiber. Of course, one of the parameters is the physical length of the fiber, which increases as the temperature increases. Another parameter is the group velocity index, ng. And the team's findings show that the correct combination of fiber properties can be used to reduce the temperature and thus counteract the increase in propagation time due to the thermal elongation of the optical fiber. (This is because the reduction of ng causes the light to travel faster in the fiber, and the rest are the same.) After analyzing and numerically simulating details of various coated and uncoated fiber designs, Southampton scientists led by OSA member Eric Numkam Fokoua produced a 2.8m long, seven-core hollow photonic bandgap fiber sample with a fill factor 96.5%, can work in the spectral area of ​​telecommunication of about 1.55μm. Then they tested the fiber at four temperature settings from 29 ° C to 82 ° C. As predicted in the simulation analysis, the TCD measurement of the fiber is zero, which means that propagation time is completely insensitive to temperature changes - for the first time, this is the result so obtained. The researchers suggest that these very low or near-zero transfer-time thermal sensitivities should significantly improve the ability of an optical signal with accurate frequency and timing to propagate through the fiber. In their opinion, this result represents "a final optical solution that gives a time-sensitive application." Golf Hole Cutter,Golf Plastic Tee,Golf Ball Tee Holder,Golf Hole Cutter Tool Shenzhen New Gaopin Sports Goods Co,Ltd , https://www.sznewgaopin.com