Protective fiber coating decides the mechanical strength of an optical fiber as well as its resistance against the influence of environment, especially in some special areas like irradiation atmospheres. According to the experiment in this paper, it was found that the tensile force and peeling force of resistant radiation optical fiber was improved because of the special optical fiber coating.
As high power fiber laser used more and more widely, to increase the output power of fiber laser and beam quality improvement have become an important goal for the development of high power fiber lasers. The use of large mode fiber is the most direct and effective way to solve the nonlinear effect and fiber damage in the fiber laser power lifting process. In order to reduce the effect of polarization of the fiber laser system, the study found that when introduces a birefringence in the single-mode fiber, the polarization state changes caused by the birefringence is far greater than the random polarization state changes, then the external disturbance is completely submerged, finally the polarization can be controlled and stabilized. Through the fine design of the fiber structure, if the birefringence is high enough to achieve the separation of the two polarization states, the fiber will have a different cut-off mechanism to eliminate polarization which is not need, which will realize single mode single polarization transmission in a band. In this paper, different types of single polarization fiber design are presented and the application of these fibers are also discussed.
In this paper, erbium doped fibers for space detection are researched for feature of radiation resistance.
Fibers with different coated carbon are hydrogen loaded and radiated, and too thick of carbon layer around fiber
would not bring best radiation-resistant performance, since thick carbon layer would make the entering of hydrogen
difficult. We also research the duration of saturated hydrogen loading under the high and low temperature
respectively, and it’s found that the fibers’ photo sensitivities tend to be flat after some days. Hydrogen is reloaded
into the fibers which have been loaded once, this help us to deep understand the mechanism of hydrogen loading for
the fiber gratings. Loss and wave width changes are also researched under different radiation dose.
Technique of residual cladding pump light detection in active fiber is researched, which is used in assembling the fiber laser system. With this technology, a fiber probe is used to detect the pump light leaking from the cladding with fiber’s coating on or stripped. It’s found that there is a linear relationship between leaking light power and pump light power, and the proportional coefficient is measured. Therefore, there’s no need to cut and fuse the active fiber many times to get the best length of active fiber, and it can save the measuring period and experiment expense a lot. Two types of fiber probes are used, tapered fiber probes and bevel fiber probes. The testing results of low light using these two fiber probes are given and the detecting method is verified.
This article analyzes the advantages and disadvantages of a packaging structure for pump coupler, where common heat conduction material is used. In this study, the possibility of using new technology of thermal conductivity is discussed. We also proposes a solution that make the function and effect of package more uniform. A serial of experiments are done for research the cooling effect and the working reliability of the fiber combiners and couplers. Experiment proves that after improved method of package, the cooling speed increases significantly comparing the sample with old type of package technique. The technique discussed in this paper will make the high power fiber laser working long time with steady power output and high efficiency.
We studied the coating technology, research shows that: to coat the internal structure of coupler we need to consider both intensity problem and heat dissipation problem. For instance: thicker coating will increase the coupler’s resistance to stress and resistance to water vapor, but we will prefer a thinner coating because it is easier to let the light pass though and generate less heat. We’ve tried a number of different coating materials, and analyzed the adhesion during its curing process. Finally, according to the experimental results, we believe that cooling capacity needs to be first considered. Recent experimental results show that we can use advanced coupler coating technology to extend the working life of the coupler. At the end of paper, we provide a coating example and show its real contribution to the working life.
In this contribution, optic fibers of a serial of doping proportions were prepared and tested. It’s found that B could decrease the sensitivity of refractive index to the temperature, and the sensitivity decreased 2% as the B’s molar percentage increased 1%. By comparing fiber samples’ test results, the proportion of Si: B: Ge to achieve the lowest Δn/ΔT was 0.75: 0.15: 0.1. After balancing the Δn/ΔT and loss, the recommended proportion of Si: B: Ge was given as 0.77: 0.15: 0.08. With this method, the optic fiber delay lines’ time delay could be reduced to 30 ps/km/°C, and their loss is lower than 0.5dB/km at 1550nm wavelength. Besides B and Ge, other kinds of elements are now being used to add into the fiber to improve the property of delay, and decay lines will make the photonic sensing more reliable and stable.
Fibers with different depths of hermetically coated carbon are hydrogen loaded and radiated, and it’s found that too thick of carbon layer around fiber can’t bring best radiation-resistant properties, because the thick carbon layer would make the entering of hydrogen difficult although it can help to stop the hydrogen escaping. We also research the duration of saturated hydrogen loading under the temperature of 30°C, 50°C and 80°C respectively, and it’s found that after 150h, 100h and 48h, the fibers’ photo sensitivities tend to be flat. Besides, in order to research the period of validity of hydrogen, some hydrogen loaded fibers are idle for from 1 day to 1 months before etched. The additional loss of these fibers are tested and compared.
In this paper, fibers with different depths of hermetically coated carbon are hydrogen loaded and radiated, and it’s found that too thick of carbon layer around fiber can’t bring best radiation-resistant properties, because the thick carbon layer would make the entering of hydrogen difficult although it can help to stop the hydrogen escaping. We also research the duration of saturated hydrogen loading under the temperature of 60°C and 100°C respectively, and it’s found that after 120h and 48h, the fibers’ photo sensitivities tend to be flat. We also reload hydrogen into the fibers which have been loaded once, and these fibers are etched then, this help us to deep understand the mechanism of hydrogen loading for the fiber gratings.
In this presentation, fibers with 2 and 3 layers of coatings are made and their sound sensitivities are
tested. It’s found that the interface between coating layers could weaken the acoustic transmission, and the acoustic
impedance is mainly due to the difference of coating material’s density and velocity of sound. The fiber with 1.0mm
diameter has the highest sound sensitivity of about 6×10-12/dyn/cm2 when commercially available coating material used. This paper also discusses the method of testing, including how to process the fiber and how to wind fiber. In
the end of this contribution, some coating materials and coating diameters are compared.