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We report on the effects of spectral shaping of the output coupler fiber Bragg grating (OC-FBG) in a Yb-doped fiber laser on the laser emission spectrum for the purpose of inhabiting stimulated Raman scattering (SRS). The lasers with four different OC-FBGs were built and characterized. We found that the laser with a multiple reflection peak chirped-moiré OC-FBG produced a broad laser emission linewidth, which, in turn, led to about 100 times lower the SRS emission as compared with the laser with a 0.19 nm Gaussian-shaped OC-FBG. A nearly flat-top laser output spectrum was obtained from the lasers with a triangle-shaped and chirped-moiré OC-FBG, respectively.

We report the design of an all-fiber, linearly polarized Yb-doped fiber laser at 1064 nm with a narrow linewidth and high output power required by the master oscillator of the amplifier for high-power spectral beam combining. The laser has achieved linearly polarized output with a polarization extinction ratio of 23 dB, a narrow linewidth of ≤52  pm, and an output power of 32.7 W. Such performance was obtained by the cavity design that incorporated a wavelength-shifted PM fiber Bragg grating pair and single-mode-multimode-single-mode structure.

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Monolayer Photoluminescence In article number 2100104 by Weizhen Liu, Haiyang Xu, and co‐workers, a novel organic superacid trifluoromethanesulfonic (TFMS) is explored to significantly improve the photoluminescence quantum yield of CVD‐grown monolayer MoS2 and WS2 to 14.1% and 56.7%, respectively. Through in‐depth study and analysis with scanning transmission electron microscopy and density functional theory calculation, luminescence enhancement mechanism is attributed to a synergistic effect of TFMS‐assisted sulfur vacancy repairation and p‐type doping.