pastervehicle.blogg.se - Mashinsky trains

Nevertheless, this system is not suitable for long-distance remote sensing due to the high loss atmospheric transmission at 7.5 µm. The QC laser was driven by a microsecond pulsed current and a precision of 2 ppm was obtained with a pulse-to-pulse normalization technique. In 2013, Chen et al., combined a Fabry-Perot quantum cascaded (QC) laser operating at 7.5 µm and a liquid nitrogen (LN) cooled HgCdTe mid-infrared detector to monitor the CH 4 concentration. To date, several optical methods have been developed to measure CH 4. Compared to the traditional sensors, optical sensors have the merits of high-precision, fast-response and durability in detecting the CH 4 concentration.

Thus, it is important to monitor the ambient CH 4 concentration in some particular places such as natural gas pipelines. However, it can cause very dangerous asphyxia or even explosion when the CH 4 concentration in the air reaches a certain level. Methane (CH 4) is a kind of greenhouse gas, as well as the main component of natural gas, biogas, coal-mine gas, etc. © 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement 1.

The wavelength of Raman pulsed laser can be tuned from 1652.0 nm to 1654.0 nm continuously with an optical signal-to-noise ratio (OSNR) of more than 35 dB. The peak power is estimated to be as high as about 30.85 W, and a 3-dB linewidth as narrow as less than 0.08 nm is achieved when the average power of 1541 nm pump is 3.1 W. The repetition-rate and the pulse-width of the 1653.7 nm pulsed laser are 100 kHz and 31 ns, respectively. A homemade high peak-power 1541 nm pulsed laser is employed to modulate and amplify a 1653.7 nm distributed feedback laser (DFB) seed synchronously in a segment of the 52-meter-long highly germania-doped fiber (HGDF). A 1541 nm laser seed is modulated into pulse trains, which will be used as the Raman pump laser, by driving a reflective semiconductor optical amplifier (RSOA) with a continuous periodic square-wave voltage.

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