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Currently, the nuclear industry needs strongly a reliable detection system to continuously monitor a coolant leak during a normal operation of reactors for the ensurance of nuclear safety. In this work, we propose a new device for the coolant leak detection based on tunable diode laser spectroscopy (TDLS) by using a compact diode laser. For the feasibility experiment, we established an experimental setup consisted of a near-IR diode laser with a wavelength of about 1392 nm, a home-made multi-pass cell and a sample injection system. The feasibility test was performed for the detection of the heavy water (D2O) leaks which can happen in a pressurized heavy water reactor (PWHR). As a result, the device based on the TDLS is shown to be operated successfully in detecting a HDO molecule, which is generated from the leaked heavy water by an isotope exchange reaction between D2O and H2O. Additionally, it is suggested that the performance of the new device, such as sensitivity and stability, can be improved by adapting a cavity enhanced absorption spectroscopy and a compact DFB diode laser. We presume that this laser-based leak detector has several advantages over the conventional techniques currently employed in the nuclear power plant, such as radiation monitoring, humidity monitoring and FT-IR spectroscopy. [ABSTRACT FROM AUTHOR]

Cross-polarized wave (XPW) generation is used for the contrast improvement of ultra-intense femtosecond laser pulses in a double CPA configuration. We present theoretical and experimental evidence that the XPW output spectrum depends in a predictable way on the input chirp. Therefore, a chirp controlled pulse can experience a pulse duration shortening up to a factor of $\sqrt{3}$ , and an initial amount of chirp that leads to the exact preservation of the spectral width of a given pulse can be predicted. [ABSTRACT FROM AUTHOR]