OH absorption in GeO2-doped fused silica fibres

The OH-ion absorption of SiO2/GeO2-core step-index multimode fibres in the 1.2?1.6 ?m region has been studied in relation to changing GeO2 concentrations. It was found that the OH absorption band at ? 1.4 ?m in SiO2/GeO2-core fibres had two components with maxima at 1.39 ?m and 1.42 ?m related to the first overtone of the fundamental OH vibration in SiO2 and GeO2, respectively.     

Viscosity of F and GeO/sub 2/ codoped silica glass

The dopant concentration dependence of the viscosity of fluorine (F) and GeO/sub 2/ codoped silica glass is investigated experimentally. The viscosity of these glasses at various dopant concentrations is measured using the drawing method in the 1700-2000 degrees C temperature range. The change in the viscosity logarithm of F and GeO/sub 2/ codoped silica glass was found to be the linear sum of the changes induced individually by F and GeO/sub 2/.<>     

Long wavelength performance of SiO2/GeO2/P2O5 core fibres with different P2O5 levels

The attenuation performance of SiO2/GeO2/P2O5 core graded index multimode fibres at 1.6 ?m has been studied in relation to changing P2O5 concentrations. Loss is related to both P2O5 doping and OH contamination levels, and reduction of both has led to a minimum fibre attenuation of 0.23 dB/km at 1.62 ?m.     

Low-Loss single-mode fibre at the material-dispersion-free wavelength of 1.27 ?m

A GeO2-doped silica single-mode optical fibre with a low attenuation loss of 0.5 dB/km at 1.27 ?m, where the material dispersion of the silica glass falls to zero, has been made by a C.V.D. technique. Attention was paid to reducing OH absorption losses in the single-mode fibre.     

Spectral loss characteristics of GeO2-P2O5-doped silica graded-index fibres in long-wavelength band

Spectral loss characteristics of GeO2-P2O5-doped silica graded-index fibres were investigated in the long-wavelength band. A broad absorption loss, increasing in proportion to the OH-ion concentration, was observed in the vicinity of 1.60 ?m wavelength.     

Tailoring zero chromatic dispersion into the 1.5?1.6 ?m low-loss spectral region of single-mode fibres

We have designed and fabricated single-mode silica fibres that have zero chromatic dispersion within the 1.5?1.6 ?m low-loss spectral region by controlling their waveguide dispersion and dopant-dependent material dispersion. These fibres have small core diameters and large core-cladding refractive-index differences, ?n = 0.018, corresponding to a 13 mole % GeO2 dopant concentration in the core. The zero-dispersion wavelength was shifted from ?0 = 1.375 ? to ?0 = 1.54 ? by decreasing the fibre core diameter from 7 ?m to 4.8 ?m. This ability to tailor the minimum dispersion wavelength to the ultra-low-loss region near 1.55 ?m is important for designing single-mode fibres for very long distance and very high capacity optical transmission.     

空芯波导用SiO2—TiO2—GeO2涂层的红外反射光谱分析

指出对于SiO2-TiO2凝胶玻璃涂层，即使TiO2含量高达80%，其对CO2激光波长(10.60μm）的IR反射率值仍很低。而对于SiO2-TiO2-GeO2涂层，当GeO2的含量从20%增加到30%时，其反射率峰逐步移向CO2激光波长，且在10.6μm处获得了20%的反射率。但当GeO2含量超过35%后，其IR反射率降低到几乎为零。因此，40SiO2-30TiO2-30GeO2的凝胶玻璃涂层是较理想的。     

Electron-beam vapour-deposited erbium-doped glass waveguide laser at 1.53 mu m

A single-transverse-mode erbium-doped glass waveguide laser operating at a wavelength of g 1.53 mu m is described. The erbium-doped GeO/sub 2/-SiO/sub 2/ core of the waveguide was made by electron-beam vapour deposition and patterned by reactive ion etching on a quartz glass substrate. The core was 10 mu m wide, 8 mu m high and 64.5 mm long, which permitted single-transverse-mode laser oscillation. The threshold pump power for CW oscillation was 150 approximately 200 mW at a pumping wavelength of 0.98 mu m.<>     

Pulse delay measurements in the zero-material-dispersion region for germanium- and phosphorus-doped silica fibres

Wavelength-dependent pulse dispersion in germanium- and phosphorus-doped silica fibres of different concentrations was measured using mode-locked subnanosecond pulses in the 1.064?1.55 ?m wavelength range. Zero dispersion for GeO2-SiO2 fibres was observed in the 1.3?1.33 ?m region depending on the concentration. P2O5-doped silica fibres showed zero dispersion near 1.28 ?m, independent of doping concentration.     

Second harmonic generation in GeO/sub 2/ ridge waveguide

Reports the first observation of 'seeded' second harmonic generation in a GeO/sub 2/ and P/sub 2/O/sub 5/ codoped silica ridge waveguide from a pump wavelength at 1.064 mu m. A 200-fold increase over the background signal has been measured.<>     

Material dispersion evaluation in a fluoride glass

We report for the first time experimental evaluation of the material dispersion in a fluoride glass. Very interesting features are observed as the wavelength of zero material dispersion is around 1.7 ?m and the disperison is about only 45 ps/nm × km at a 4 ?m wavelength.     

Refractive index dispersion of lightguide glasses at high temperature

The refractive index of pure and GeO2-doped silica glasses was measured at wavelengths from 0.4 ?m to 2.1 ?m, over a temperature range from 20°C to 540°C. Values for the thermal coefficient of the refractive index (about 1.2×10?5/°C at 1.3 ?m) were almost identical for both glasses. The data showed that material dispersion for optical fibres increases with increasing temperature.     

GeO2介质膜空芯传能光纤的传输特性分析

介绍了GeO2介质膜空芯传能光纤的基本结构和相关的Miyagi传输损耗公式。在此基础上将通过实验得到的GeO2介质膜空芯光纤中HE11模在空芯光纤处于直线状态和弯曲状态下实测损耗值与Miyagi传输损耗公式经过插值运算得到的理论预测损耗曲线进行了比较，并分析了两者存在差异的原因。最后给出了GeO2介质膜空芯光纤在其处于直线和弯曲状态下的输出能量分布特性。     

Profile dispersion in multimode fibres: measurement and analysis

An electronically scanned interference microscope has been used to measure the refractive-index profile and its dispersion in optical fibres. From these measurements, we find that the power-law profile that best equalises modal delays in GeO2-S1O2 fibres should have an exponent that varies between 1.9 and 2.5 in the wavelength range from 0.5 to 1.1 ?m and is close to 2 at 0.9 ?m.     

Pressure-dependent Sellmeier coefficients and material dispersionsfor silica fiber glass

The pressure-dependent Sellmeier coefficients are essential to characterize the optical design parameters for the optical fiber communication systems under deep sea environmental conditions. These coefficients are calculated for densified silica glass for the first time to compute the pressure dependence of material dispersion at any wavelength from the ultraviolet (UV) to 1.71 μm. The zero dispersion wavelength λ₀ (1.2725 μm at 0.1 10⁶ N m ^-2) varies linearly with pressure, and dλ₀/dP is 0.0027 nm/(10⁶ N m^-2). The calculated value is approximately one-third of the experimental value of 0.0076 nm/(10⁶ N m^-2) for a germanium-doped dispersion shifted fiber having λ₀=1.5484 μm and -0.0070 nm/(10⁶ N m^-2) for a pure silica-core fiber cable having λ₀ =1.2860 μm. Since, the refractive indexes are increased with pressure, the negative value of shift of the zero-dispersion wavelength is erroneous. The explanations are due to Ge-doping in silica glass, a possible temperature fluctuation of 0.16°C in the pressure-dependent measurement system of the zero dispersion wavelength and different experimental conditions of the silica glass and the optical fibers. This anomaly can also be attributed to the internal strain development at the core-cladding and fiber-jacketing boundaries due to pressure, which shows a larger experimental value. It accounts for the experimental values satisfactorily     

Low-loss optical glass fibre with Al2O3-SiO2 core

Optical glass fibres, consisting of an Al2O3-SiO2 core and SiO2 cladding, were produced by using a glass growth technique of vapour deposition in a flame. The core measured from 4 to 10 ? in diameter, and the difference in refractive index between the core and the cladding was 0.003. The lowest loss of this fibre was 10 dB/km at 0.66 ?m.     

Low-OH-absorption fluoride glass infra-red optical fibres

Ultralow losses of 10?2 to 10?3 dB/km have been predicted in fluoride glass optical fibres between 2 and 4.5 ?m. At 2.9 ?m, in the central part of this spectral region, the OH? ion presents its fundamental stretching vibration which gives rise to a strong and broad absorption. The attenuation at 2.9 ?m in a step-index fluorozirconate glass fibre has been brought down to 58 dB/km, by reducing the OH? concentration in the glass. It is the lowest attenuation yet reported at this wavelength in any optical fibre.     

Low-loss fibre prepared under high deposition rate by modified c.v.d. technique

Graded-index fibres with a GeO2-P2O5-SiO2 core have been prepared by a modified c.v.d. and drawing process. The deposition rate of the core glass was 0.17 cm3/min (0.37 g/min), and the fibres have an attenuation of 2.6 dB/km at 0.83 ?m and a 6 dB bandwidth of 816 MHz km.     

Transmission properties of 2.55 ?m fluoride glass fibre

Data transmission and bandwidth measurements have been performed on a fluoride glass fibre at the 2.55 ?m minimum loss wavelength of the fibre, using a colour centre laser and an external waveguide modulator. Fibre modal dispersion limited the fibre bandwidth to 360 MHz.     

Dispersive and scattering properties of a ZrF4 based glass

In a previous letter we presented the material dispersion in a ZrF4 based fluoride glass. The zero crossover wavelength ?c was found to occur between 1.6 and 1.7 ?m. Here, we analyse the refractive index measurements against wavelength data in order to obtain some physical parameters of this material on which ?c is dependent: electronic energy gap E0, electronic oscillator strength ED, lattice oscillator strength E1 and structure factor B. Such values, which are not yet known for fluoride glasses, will be then compared with those corresponding to SiO2 glass. Evaluation of the Rayleigh scattering coefficient will also be made.