摘要:

The broad spectrum of radiation from first-order stimulated Raman scattering in glass fibres leads to a spread of transverse Stokes fields in a single-mode fibre. A general expression for the effective core area (ECA) for the laser-pump ith longitudinal Stokes-mode interaction has been found. Computations of the variation of ECA withV-value are presented, together with a single ECA for use when computing the total Stokes power.

DOI:10.1049/ip-j.1985.0044

出版商:IEE    

年代:1985

数据来源: IET

摘要:

The results of a model for the static properties of laser diodes based on the beam propagation method (BPM) are compared to those of other modelling techniques. The agreement between these models is discussed, as well as the influence of longitudinal intensity variations which are taken into account by the BPM-model.

DOI:10.1049/ip-j.1985.0045

出版商:IEE    

年代:1985

数据来源: IET

摘要:

The design of a cylindrical hollow-cored Bragg fibre for HE11-like mode propagation is presented. The bulk of the propagating power can be contained in the hollow core, leading to material and leakage loss values of interest in the longer wavelength regions at and beyond 10.6 µm. For example, for a core radius of 1 mm, four cladding layers with alternate indices 1.5 and 2.38, the loss would be approximately 4.10−2dB/m at a wavelength of 10.6 µm. The loss can, in general, be further reduced either by increasing the core radius, the index difference between cladding layers, or the number of these layers.

DOI:10.1049/ip-j.1985.0046

出版商:IEE    

年代:1985

数据来源: IET

摘要:

Optical-fibre development to date has concentrated on their use in systems for telecommunications and data transfer. The realisation that optical fibres could also be used for sensors and sensing systems has increased rapidly in recent years. Judged by the large number of publications in this area the research effort is extensive, but few systems have yet been put to practical use. A critical review of recent developments is therefore useful at this stage. Several examples of fibre-optic sensors are given, where their selection has been dependent on the system showing some practical viability, and data having been obtained relevant to operation in a real (as distinct from purely laboratory) environment. Devices ranging from simple fibre-optic switches and pollution monitoring equipment, to highly sensitive acoustic, magnetic and rotation sensing systems are emerging, where an understanding of modal and polarisation effects in single-mode fibres is necessary. At present each sensor system tends to be aimed at specific application areas, where the form of acceptance by the user will vary. It is emphasised that such developments require engineering inputs at the earliest possible stage. The use of optical fibres for direct actuation of valves and sensors has now closed the optical control loop.

DOI:10.1049/ip-j.1985.0047

出版商:IEE    

年代:1985

数据来源: IET