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Feature Article - Semiconductor Superlattices with Small Band Offsets

100%

Yang G., Lewandowski L., Furdyna J., Ram-Mohan L.

Acta Physica Polonica A

1998

vol. 93

issue 4

567-600

Optical transitions in small band offset superlattices are studied within the framework of the nearly free electron approximation, in which the weak superlattice potential is treated as a perturbation. Interband selection rules are derived for transitions involving conduction and valence band states at the superlattice Brillouin zone center and the zone edge. It is found that a number of new transitions can occur in such small-offset superlattices due to wave function mixing of different subband states. The effect of the effective mass on the optical transitions is also discussed. The theory is used to explain the results observed in magneto-optical absorption experiment in ZnSe/Zn_{1-x}Mn_{x}Se small-offset superlattices. Furthermore, the nearly free electron formulation is found to be in excellent agreement with rigorous multi-band numerical calculation on superlattices involving small band offsets.

Comparison of Bragg and Polarimetric Optical Fiber Sensors for Stress Monitoring in Composite Materials

52%

Domanski A., Lesiak P., Milenko K., Budaszewski D., Chychlowski M., Ertman S., Tefelska M., Wolinski T., Jedrzejewski K., Lewandowski L., Jasiewicz W., Helsztynski J., Boczkowska A.

Acta Physica Polonica A

2009

vol. 116

issue 3

294-297

Composite structures are made of two or more components with significantly different physical or chemical properties and they remain separate and distinct in a macroscopic level within the finished structure. This feature allows for introducing optical fiber sensors into the composite material. These sensors can demonstrate stress distribution inside tested material influenced by external tensions. Two types of the optical fiber sensors are used as the 3D structure. One of them is based on application of fiber Bragg grating inside the core of the fiber. Longitudinal stress changes parameters of the Bragg grating and simultaneously, spectral characteristics of the light transmitted through the fiber. The second one is based on application of highly birefringent fibers which, under external stress, introduce polarization changes of the output light.

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2 Acta Physica Polonica A

1 2009

1 1998

2 Lewandowski L.

1 Boczkowska A.

1 Budaszewski D.

1 Chychlowski M.

1 Domanski A.

1 Ertman S.

1 Furdyna J.

1 Helsztynski J.

1 Jasiewicz W.

1 Jedrzejewski K.

1 Lesiak P.

1 Milenko K.

1 Ram-Mohan L.

1 Tefelska M.

1 Wolinski T.

1 Yang G.

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Feature Article - Semiconductor Superlattices with Small Band Offsets

Comparison of Bragg and Polarimetric Optical Fiber Sensors for Stress Monitoring in Composite Materials