Most of irradiation resistant fibers are designed to contain pure quartz fiber core to ensure good irradiation resistant performance. However, multimode (MM) fiber containing pure quartz core owns lower bandwidth because of the step index (SI) distribution. Thereby the application of it will be limited though the irradiation resistance is fine attributing to pure quartz core. To combine better irradiation resistance and higher bandwidth, a novel irradiation resistant and high bandwidth MM fiber (RMM-fiber) being of special waveguide was designed and experimental investigated via testing attenuation, bandwidth and mechanical strength before and after <sup>60</sup>Co radiation (up to 25 Mrad(Si), 10 Mrad(Si)/s). It is indicated that the RMM-fiber owns lower irradiation induced attenuation comparing with normal MM fiber, and the bandwidth after irradiation is 403.1 MHz km @1300 nm that is much higher than SI type MM fiber. The RMM-fiber shows no reduction but a little rising on mechanical strength. Additionally, it has outstanding environmental suitability in -100°C~+125°C temperature cycling test.
In recent years, the power level of laser outputting from twins fiber, being of pump unit fiber and gain unit fiber, is continuing rising. However, little report is focused on the pump coupling efficiency and thermal management on account of the distinctive waveguide of twins fiber. In this paper, the experiment study was launched on pump coupling efficiency and thermal management based on our previous work. To facilitate observing, two waveguides were designed as “cycle pump unit + octagonal gain unit” and “cycle pump unit + cycle gain unit”, while both gain units contained no doping core and the claddings were all 125 um approximately. It indicated that the pump power proportion between pump unit and gain unit was gradually changing with increasing of fiber length when the fiber was pumped from only one side of pump unit. The dynamic balance of pump power proportion could be obtained as the length of “cycle pump unit + octagonal gain unit” twins fiber is more than 4 m. By contrast, the balance point appeared earlier for “cycle pump unit + cycle gain unit” twins fiber before the length was up to 4 m. Further, the laser experiment was executed by using typical twins fiber that was consisted of one octagonal gain unit, containing Ytterbium (Yb) doped fiber core, and cycle pump unit. When the power was pumped into the fiber from the pump unit, the temperature of pumping point was obviously lower than conventional double cladding active fiber.
The process of preparing fluorine-doped multimode gradient optical fiber preform by MCVD is studied in this paper. Different core reactants are doped to form different core refractive index distributions. It is found that the core with more germanic chloride and phosphorus has better refractive index distribution. But it is not conducive to the radiation resistance of the fiber.
A novel well weathering resistant power delivery fiber which is of double cladding and high optical energy transmitting ability is developed via fluoroplastic out sheath extruding process. The fiber has been comprehensively evaluated including optical performance, mechanical performance, environmental suitability and laser transmitting property. It is shown that the fiber has not only low attenuation, high numerical aperture and better mechanical bending performance, but also outstanding weathering resistance and high power laser transmitting performance, which implies the qualification of the fiber for various kinds of applying situations, such as laser ignition, laser induced expanding sound underwater, ship-based and airborne laser weapon.
The power output of 2km and 8km 80μm selected cut-off wavelength single mode optical fiber was measured by 2.4W ASE fiber source at 1550nm waveband. The results show that obvious nonlinearity in 2km fiber does not occur by way of output power and spectrum. Slight nonlinearity is seen in 8km fiber. The power variation is small during the test of power stability with 1.28W input in 8km fiber.
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 <i>Δn/ΔT</i> was 0.75: 0.15: 0.1. After balancing the <i>Δn/ΔT</i> 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.
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<sup>-12</sup>/dyn/cm<sup>2</sup> 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.
2.0μm emission properties of Ho<sup>3+</sup>-Yb<sup>3+</sup> co-doped tellurite oxy-halide glass exited by 980nm LD is
reported. Mid-infrared transmittance property of glass was investigated by Fouriertransform infrared (FTIR)
spectrometer. The Judd-Ofelt intensity parameters Ω<sub>t</sub>)<i>t=2,4,6)</i> , spontaneous radiative transition probabilities, branching ratios and radiative lifetime of Ho3+ were calculated according to the absorption spectra by using Judd-Ofelt theory. The absorption, emission cross-sections and gain coefficient of Ho<sup>3+</sup>:<sup>5</sup>I<sub>7</sub>→<sup>5</sup>I<sub>8</sub> are calculated based on the McCumber and Reciprocity theories. Results indicate that the maximum 2.0μm emission intensity of Ho<sup>3+</sup> was achieved
at 0.15mol% Ho<sub>2</sub>O<sub>3</sub> and 1.5mol% Yb2O3 concentrations in tellurite oxy-halide glass. The maximum absorption and
stimulated emission cross-section of Ho<sup>3+</sup> near 1944nm are 6.37 x 10<sup>-21</sup>0cm<sup>2</sup> at 2.0μm and 10.94 x 10<sup>-21</sup>cm<sup>2</sup> respectively. The results suggest Ho<sup>3+</sup>-Yb<sup>3+</sup> co-doped tellurite oxy-halide glass is a good candidate for efficient 2.0μm