3.1†kW 1050†nm narrow linewidth pumping-sharing oscillator-amplifier with an optical signal-to-noise ratio of 45.5†dB.

In this paper, the amplified spontaneous emission (ASE) suppression in a 1050 nm fiber laser with a pump-sharing oscillator-amplifier (PSOA) structure is studied theoretically and experimentally. A theoretical model of a fiber laser with a PSOA structure is established. The characteristics of the ASE for the PSOA structure and the pump-independent oscillator-amplifier (PIOA) structure are compared and analyzed. The experimental results show that the ASE can be effectively suppressed by utilizing the PSOA structure, which agree with the simulation results. A 1050 nm high-power narrow-linewidth fiber laser with PSOA structure is demonstrated, in which the gain fiber lengths of the oscillator and amplifier are 1.6 m and 9 m, respectively, to ensure the interconnection of pump power between the oscillator and amplifier. Finally, the maximum output power of 3.1 kW has been achieved, the linewidth is 0.22 nm at 3 dB, the beam quality M2 ≈ 1.33, and the optical signal-to-noise ratio (OSNR) is 45.5 dB.

Stokes light induced modulation instability in high power continuous wave fiber amplifiers.

In this paper, Stokes light induced modulation instability (MI) in high power continuous wave (CW) fiber amplifiers is observed. The investigation shows that the Stokes light generated by inter-modal four wave mixing (IMFWM) and stimulated Raman scattering (SRS) in high power fiber amplifiers can be modulated by the signal light through XPM and cause MI. Then, a sideband will be generated around the second-order Raman frequency shift, which is amplified by SRS and shown as a train of pulses in time domain. It is shown that the frequency shift of the sideband will be influenced by IMFWM and SRS. In addition, the sideband was found to be blue-shifted with the increase of the power, which indicates that the frequency shift of the sideband is mainly depended on MI, while SRS plays the role of amplification.

Fast fiber mode decomposition with a lensless fiber-point-diffraction interferometer: publisher's note.

This publisher's note contains corrections to Opt. Lett.46, 2501 (2021)OPLEDP0146-959210.1364/OL.426833.

Fast fiber mode decomposition with a lensless fiber-point-diffraction interferometer.

Recently, the growing interest in few-mode fibers in telecommunications and high-power lasers has stimulated the demand for fiber mode decomposition (MD). Here we present a fast fiber MD method with a lensless fiber-point-diffraction interferometer. The complex amplitude at the fiber end is achieved by the polarization phase-shifting technique and the lensless imaging technique. Then, the eigenmode coefficients are determined by the mode orthogonal operations of the complex amplitude. In the experiment, the SMF-28e fiber containing 10 linear polarized modes at the wavelength of 632.8 nm is studied for MD. The decomposition of the 50 * 50 pixels interferograms takes only 0.0168 s. The similarity of the intensity patterns of the testing light is larger than 97% before and after the MD. This new, to the best of our knowledge, method can achieve fast and accurate 10-mode MD without using any imaging systems.