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1.89 kW cylindrical vector beams (CVBs) at 1,064 nm with the 3 dB linewidth being about 0.08 nm have been generated from a narrow linewidth all-fiber linearly-polarized laser by metasurface extra-cavity conversion. At the maximum output power, the transmission efficiency, mode purity of radially polarized cylindrical vector beams (RP-CVBs) are 97% and 92.7%, respectively. To the best of our knowledge, this is the highest power of narrow linewidth CVBs generated from fiber laser. The temperature of the metasurface is moderate, and the maximum temperature is 75.5°C at 1.89 kW, which means that the system can be further power scaled. The evolution of mode purity has been analyzed numerically, and the influence of high-order modes (HOM) in laser source and thermal effects of metasurface has been calculated, which reveals that the presence of high-order modes and the temperature rise of metasurface degrade the mode purity of the CVBs. Among them, HOM causes a degradation of 1.68%, thermal lensing effect contributes 2.32%, and the microstructure variation of the metasurface contributes the remaining 3.3%.

A multiwavelength erbium-doped fiber ring laser is proposed, which is based on two Mach–Zehnder interferometers in a cascade configuration. One of the interferometers acts as a wavelength filter, and the other, exhibiting a relatively small optical path difference, determines the number of lasing wavelengths. By the use of an optical switch, the operating wavelengths can be shifted between two wavelength bands, centered at 1555 and 1565 nm. A stable simultaneous ten-wavelength lasing operation with amplitude fluctuations <5 dB, wavelength spacing ≈0.5 nm, and signal-to-noise ratio >25 dB over the whole operating wavelength region has been obtained. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 32: 458–461, 2002. [ABSTRACT FROM AUTHOR]