Fiber-optic spectroscopic rotational Raman lidar with visible wavelength fiber Bragg grating for atmospheric temperature measurement

•A rotational Raman lidar is demonstrated with visible wavelength fiber Bragg grating.•Two rotational Raman signals are extracted by two sets of fiber Bragg gratings.•Visible wavelength fiber Bragg grating is fabricated by zero-order nulled phase mask.•The out-of-band rejection is tested to ensure rotational Raman spectral purity.•Preliminary experiment is executed to assess capability of fiber-optic spectroscope.

A fiber-optic spectroscopic rotational Raman lidar is demonstrated with the visible wavelength fiber Bragg grating technique for profiling the atmospheric temperature. Two-channel pure rotational Raman optical signals are extracted from lidar echo signals by two sets of visible wavelength fiber Bragg gratings. The rejection-type of fiber Bragg grating in visible region is successfully fabricated through the zero-order nulled phase mask. Its most significant parameter, out-of-band rejection, for fiber-optic spectroscopic system is tested to ensure the spectral purity of rotational Raman channel. A temperature profile up to a 0.7-km height is obtained by pure rotational Raman lidar with 300-mJ laser pulse energy, and a 250-mm telescope. Preliminary results of observations show that this fiber-optic spectroscopic scheme with high mechanical stability has >70-dB suppression to elastic backscattering in lidar echo signals.