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Accurate measuring temperature-dependent thermal conductivities of (Ti,Al)N ceramic coating is important to quantitatively analyze the thermal effects of (Ti,Al)N ceramic coating on the heat generation and heat transfer during cutting process by PVD (Ti,Al)N coated cemented tools. In this paper, the temperature-dependent thermal conductivities of PVD Ti0.55Al0.45N ceramic coating with coating thickness of 2 µm in the temperature ranges of 25–500 °C are measured by time domain thermo-reflectance method. Firstly, the detailed deposition process and microstructure characterization of PVD Ti0.55Al0.45N ceramic coating are presented. Secondly, the measuring principle and measuring procedure of PVD ceramic coating thermal conductivity with the time domain thermo-reflectance are proposed. Then, the measured thermal properties of substrate are used in the calculation algorithm to obtain the thermal conductivity of Ti0.55Al0.45N ceramic coating at the specific temperature, which can eliminate the variation influences of substrate thermal properties with temperature. Lastly, the obtained thermal conductivities of PVD Ti0.55Al0.45N ceramic coating are verified to be increased with the increase of temperature in the temperature ranges of 25–500 °C. The relationship between the thermal conductivity of PVD Ti0.55Al0.45N coating and temperature can be represented by quadratic polynominal equation. The applied time domain thermo-reflectance method is useful for measuring the temperature-dependent thermal conductivities of similar ceramic coatings in the temperature ranges of 25–500 °C.

In this paper we introduce novel time-resolved photoluminescence spectroscopy called femtosecond two pulses induced stimulated emission spectroscopy, in which the generated nonlinear photoluminescence signal was used to identify the ultrafast dynamics of stimulated emission process in the semiconductor material. By employing two collinear fundamental femtosecond laser beams, we systematically investigated time-resolved multiphoton-induced amplified spontaneous emission in ZnO single crystal. Our results demonstrate the feasibility of this technique with the advantage of easy setup and high time resolution.

Broadening of white-light continuum is observed by filamentation of near-infrared femtosecond laser pulses with peak power exceeding the megawatt level in BK7 glass with the presence of the zero-dispersion point. The simulated results show that, due to the low dispersion at the zero-dispersion point, the broadening of white-light continuum can be wider and the filament can persist in propagating stably longer distance.