Fig. 4: Spatial, spectral, and polarization analysis of laser emission. | Nature Communications

Fig. 4: Spatial, spectral, and polarization analysis of laser emission.

From: Continuous-wave upconversion lasing with a sub-10 W cm−2 threshold enabled by atomic disorder in the host matrix

Fig. 4

a Schematic of WGM analysis in an LQUM determined by circulation direction (clockwise (CW) and counterclockwise (CCW)) and transverse modes (transverse magnetic (TM) and transverse electric (TE) modes). b Spatially resolved spectrum of laser emission from the LQUM. The narrow rectangular section was spatially selected by the spectrograph’s entrance slit of 2 μm and resolved using a high-resolution grating of 1200 lines mm−1 (centered at 500 nm). Along with vertical direction, each point of the selected area generates emission spectrum horizontally on the panel of EMCCD to create the image of b. c Deconvolution of the laser lines using Gaussian-Lorentz fitting. d–f Polarization investigation of the laser lines using the emission spectrum (d), a polar plot of the intensities (e) and the intensity ratio (f). The fitting curves in e and f were drawn by a cosine-square function.

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