We demonstrate a nonadiabatic microfiber sensor with a taper diameter of few micrometers. The modal interference caused by the abrupt taper results in a sinusoidal spectral response. The wavelength shift arising from the changes in the external refractive index is found to be significant with a maximum sensitivity of 18681.82nm/RIU achieved. The measured results show a good agreement with the theoretical predictions. The high sensitivity and the simplicity offer the sensor the potential for many real applications.

The residual stress distributions caused by the deep cold rolling (DCR) process, with a focus on the distributions at the boundary of the treatment zone, are examined in this study. A three-dimensional finite-element (FE) model, validated with experimental residual stress data, is used to study the effect of the process. The residual stress distribution in the crosswise direction (perpendicular to rolling direction) shows a region of tensile residual stress at the start and end of the track that may be a cause for concern. The reason for this region of tensile stress is likely to be due to the reduced treatment of the start and end zones due to the step over and the tool path taken. Other factors that cause a difference between the steady state and the transient zone of the burnished area are also investigated. It is shown that the net material movement causes larger plastic deformation in the boundary zone between the burnished and unburnished region of DCR.

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A new structure of Long-Period Gratings (LPGs) sensor is introduced as a sensitive ambient RI sensor. This structure consists of creating periodic corrugations on the cladding of the LPG. The experimental results show that this LPG structure has good performances in terms of linearity and sensitivity and serves as a highly sensitive and cost-effective sensor. It also has the advantage of portability as the corrugation can also serve as the reservoir for the specimen collection to be tested.

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