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The use of thin polymer films in optical planar integrated optical circuits is rapidly increasing. Much interest, therefore, has been devoted to characterizing the optical and mechanical properties of thin polymer films. This study focuses on measuring the elasto-optical properties of three different polymers; polystyrene, polymethyl-methacrylate, and benzocyclobutane. The out-of-plane elastic modulus, refractive index, film thickness, and birefringence of thin polymer films were determined by means of the prism coupling technique. The effect of the applied stress on the refractive index and birefringence of the films was investigated. Three-dimensional finite element method analysis was used so as to obtain the principal stresses for each polymer system, and combining them with the stress dependent refractive index measurements, the elasto-optic coefficients of the polymer films were determined. It was found that the applied stress in the out-of-plane direction of the thin films investigated leads to negative elasto-optic coefficients, as observed for all the three thin polymer films. [ABSTRACT FROM AUTHOR]

In this study, the magnetic transitions and the magnetic characteristics of the thermally induced martensitic transformations in Fe-13.2%Mn-5.3%Co alloy have been investigated. The microstructure analysis of difusionless phase transformations forming in the alloy were performed by scanning electron microscopy (SEM), and the magnetic properties were revealed by Mössbauer spectroscopy and AC susceptibility. SEM observations reveal that two types of thermal-induced martensites, ε (h.c.p.) and α' (b.c.c.) martensites, form in the austenite grains of the alloy. Mössbauer spectra at room temperature reveal a paramagnetic character with a singlet for the γ (f.c.c.) austenite and ε martensite phases and a ferromagnetic character with a broad sextet for α' martensite phase. In addition, measurement of the AC susceptibility of the alloy shows that the magnetic transition from the paramagnetic order to magnetic disordered occurs below room temperature at 258 K. [ABSTRACT FROM AUTHOR]