摘要:

We carry out a systematic study of proton-exchange waveguides fabricated using orthophosphoric and pyrophosphoric acid. Proton-exchange is carried out using three different processes: surface-coating, spin-coating, and immersion. Waveguide refractive index profiles and effective diffusion coefficients (210°C to 235°C), as determined from optical waveguide prism coupling measurements, have been compared to those of waveguides fabricated by immersion in benzoic acid. In addition to there being no apparent differences in the optical quality and properties of waveguides fabricated using phosphoric and benzoic acids, contrary to previous reports, we do not find any major advantages in using the surface coating or spin coating techniques for waveguide fabrication. The only situation in which we have obtained as high a value of Δneas has been claimed by other workers, e.g. Δne= 0.145, λ = 0.6328 μm, is where the waveguide refractive index profile is calculated using the inverse WKB method for waveguides which support only three or four modes. Under such conditions, the IWKB method is inaccurate.

DOI:10.1049/ip-j.1989.0046

出版商:IEE    

年代:1989

数据来源: IET

摘要:

The spectral dependence of the stimulated Raman gain coefficient for the GeO2-SiO2glass system is deduced by measurement of the spontaneous Raman scattered light from optical fibre preforms doped with up to 65 mol% germania. For Raman shifts in the range 100–600 cm−1the Raman cross-section is found to depend linearly on the germania concentration. This data enables the computation of the Raman gain spectra for a given core germania concentration, and as examples the gain properties in the 1.5–1.6 μm low-loss optical telecommunications window of silica-based Raman fibre amplifiers doped with 3 and 22 mol% germania are discussed.

DOI:10.1049/ip-j.1989.0047

出版商:IEE    

年代:1989

数据来源: IET

摘要:

An interlaboratory comparison of measurements on six single-mode fibres of different designs, both conventional and dispersion modified, has been performed in the framework of COST 217 Project. This measurement campaign was aimed at the evaluation and optimisation of the various measurement techniques. The measured quantities included mode field diameter, cutoff wavelength, chromatic dispersion, geometrical parameters and refractive-index profile. The agreement was generally better for conventional than for dispersion modified fibres. Although for dispersion and geometrical parameters the comparison was quite satisfactory, for mode field diameter and cutoff wavelengths the higher discrepancies were such as to require a further refinement of the relative measurement methods, particularly in dispersion modified fibres.

DOI:10.1049/ip-j.1989.0049

出版商:IEE    

年代:1989

数据来源: IET

摘要:

In order to measure voltage efficiently at several points, the optical passive multi-point sensing system (OPMSS) is investigated, and the results of the experimental system, which consists of a 400 mGI-type 50/125 μm single fibre, three fibre optic couplers and four BSO voltage sensors, are shown. The applied voltage is 0 ̃ 600 Vrms, 50 HzAC. To improve the accuracy, the area measurement method is used.

DOI:10.1049/ip-j.1989.0050

出版商:IEE    

年代:1989

数据来源: IET

摘要:

Previously, the transmission-line laser model (TLLM) was shown to be a good model for ultra-short pulse propagation in semicondcutor laser amplifiers under heavy saturation. However, the spectral shift associated with dynamic saturation has not yet been considered. The paper shows that the TLLM correctly predicts frequency shifts caused by index changes during amplification.

DOI:10.1049/ip-j.1989.0051

出版商:IEE    

年代:1989

数据来源: IET