光纤耦合器结构的红外光谱研究

为获得性能优良的熔锥型光纤耦合器．利用740FT-IR显微红外光谱仪，研究了不同制作工艺条件下耦合器中石英玻璃结构的差异。测定了在不同拉伸速度时制作的光纤耦合器，石英玻璃在650．2000cm^-1波数范围内的红外吸收光谱．观察到了石英光纤玻璃的两个特征峰，由Si-O-Si反对称伸缩振动引起的特征峰940．950cm^-1和由Si-O-Si对称伸缩振动引起的特征峰770—780cm^-1。由于工艺条件的不同，特征峰的强度和位置都发生了变化，并测量了其变化的大小。拉制速度越快，石英玻璃中Si-O-Si键的不对称伸缩振动越强．且波数的移动与光纤耦合器的性能密切相关。

Structure of optical fibre coupler with the infrared spectrometer

To obtain excellent performance optical fiber couplers,the structural difference of SiO2 in couplers under different manufacturing technique was investigated with 740 FT-IR micro infrared spectrometer.The infrared absorption spectra of SiO2 in couplers fabricated at different drawing velocities was measured. Two characteristic peaks in 650-2000 cm^-1 are observed.One characteristic peak is at about 943 cm^-1, which attributes to Si-O-Si bond asymmetric stretching vibration, the other is at about 773 cm^-1, which attributes to Si-O-Si bond symmetric stretching vibration. From the infrared spectrum,it is found that the characteristic peaks changes while the manufacturing technique is different. And the changing amount is measured.It is concluded that the asymmetric vibration of Si-O-Si is stronger in the glass of fiber coupler,and the wavenumber shift is the most important to the performance of the optical fiber couplers.