摘要:

Simple explicit expressions have been derived for the linewidth enhancement factor α and the change in refractive index with injected carrier density in direct-gap semiconductors. Both strict and partial conservation of crystal momentum have been considered. Both models yield the same expressions for α. Excellent agreement is found both between these expressions and numerical Kramers-Kronig transforms and with experimental data for λ = 1.5 μm InGaAsP. As a consequence of this analysis the factors which influence the linewidth enhancement factor can be readily understood for the first time. In particular the band-to-band contribution to α is shown to depend, in a simple way, only on the temperature, the position of the conduction band quasi-Fermi level and the difference between the photon and band-gap energies.

DOI:10.1049/ip-j.1987.0037

出版商:IEE    

年代:1987

数据来源: IET

摘要:

This paper describes the first lasing experiment of the heterostructure semiconductor Raman laser with a GaP Raman active layer as thin as 15 μm and AlxGa1−xP cladding layers for optical confinement, which should be a step towards realising a semiconductor Raman laser pumped by a semiconductor injection laser applicable to wideband optical communication. Also, the four-layer structure Raman laser is reported, by which the strain-induced optical anisotropy caused by the lattice mismatching can be reduced.

DOI:10.1049/ip-j.1987.0038

出版商:IEE    

年代:1987

数据来源: IET

摘要:

The scalar propagation characteristics of a bent optical waveguide are investigated. Using a first-order perturbation theory, analytic solutions for the fields and propagation constants of any mode, of either even or odd symmetry, are obtained. The bend breaks the degeneracy of the higher-order scalar propagation constants, and the modes become truly polarised with fixed field directions in the fibre. A more exact analysis is used to investigate the modal properties of the bent slab waveguide, and an expression for the radiation point, which is the point in the cladding at which the field becomes radiative, is derived. Using a Gaussian function to approximate the fields, the range of validity of the perturbation expansion is discussed.

DOI:10.1049/ip-j.1987.0039

出版商:IEE    

年代:1987

数据来源: IET

摘要:

Using the elementary theory of the acousto-optic nonlinear interaction, an empirical formula is developed for the diffracted light in terms of the acoustic power. Using this formula, closed-form expressions, in terms of the modified Bessel functions, are obtained for the diffracted-light components resulting from interaction with a multisinusoidal acoustic wave.

DOI:10.1049/ip-j.1987.0040

出版商:IEE    

年代:1987

数据来源: IET

摘要:

The multilongitudinal mode model, which was presented recently by Van de Capelleet al., is used to calculate several C3laser properties and parameter dependencies. It is shown that this model is capable of quantifying some C3laser properties and of fits experimentally measured C3laser behaviour better than the effective mirror model.

DOI:10.1049/ip-j.1987.0041

出版商:IEE    

年代:1987

数据来源: IET

摘要:

The effects of bandgap narrowing, surface recombination and lifetime on the performance ofn+p-diffused-junction silicon solar cells are analysed, and experimental results are given to show that the bulk recombination in the n+-diffused region plays an important role in limiting the open-circuit voltage of solar cells. The analysis shows that the surface effects are relatively unimportant in diffused-junction solar cells with surface doping concentration above 1020/cm3because of the low lifetime due to phonon-assisted recombination in addition to Auger recombination in the heavily doped layer.The analysis also brings out the effects of bandgap-narrowing models and lifetime models on the estimated carrier-concentration distributions, short-circuit currents and open-circuit voltages of solar cells. The theoretical results are compared with the experimental data obtained onn+psolar cells having differentn+-layer thicknesses and different surface concentrations, to demonstrate the tenability of the bandgapnarrowing and lifetime models used in the analysis.

DOI:10.1049/ip-j.1987.0042

出版商:IEE    

年代:1987

数据来源: IET