Experimental and numerical study of different mode-locking techniques in holmium fiber laser with a ring cavity.

Experimental and numerical study has been performed for three techniques of mode-locking in all-fiber Holmium laser. We have compared the fundamental repetition rate pulsed generation for mode-locking based on: nonlinear polarization evolution, polymer-free single-walled carbon nanotubes, and hybrid mode-locking. Experimental and numerical simulation results demonstrated the shortest pulse duration and maximum spectrum width for mode-locking based on the nonlinear polarization evolution: 1.

Dumbbell-Shaped Ho-Doped Fiber Laser Mode-Locked by Polymer-Free Single-Walled Carbon Nanotubes Saturable Absorber.

We propose a simple dumbbell-shaped scheme of a Holmium-doped fiber laser incorporating a minimum number of optical elements. Mode-locking regimes were realized with the help of polymer-free single-walled carbon nanotubes (SWCNTs) synthesized using an aerosol (floating catalyst) CVD method. We show that such a laser scheme is structurally simple and more efficient than a conventional one using a ring cavity and a similar set of optical elements.

2D Temperature Field Reconstruction Using Optical Frequency Domain Reflectometry and Machine-Learning Algorithms.

We present experimental results on the reconstruction of the 2D temperature field on the surface of a 250 × 250 mm sensor panel based on the distributed frequency shift measured by an optical backscatter reflectometer. A linear regression and a feed-forward neural network algorithm, trained by varying the temperature field and capturing thermal images of the panel, are used for the reconstruction. In this approach, we do not use any information about the exact trajectory of the fiber, material properties of the sensor panel, and a temperature sensitivity coefficient of the fiber.

All-fiber 1125 nm spectrally selected subnanosecond source.

In this paper, we demonstrate the selection of radiation from the stimulated Raman scattered radiation, while using a spectral filter, based on a high-reflection fiber Bragg grating and an optical circulator. As a result, a stable pulsed signal was obtained at a wavelength of 1125 nm with a repetition rate of 1 MHz. The pulse duration and energy varied from 120 to 173 ps and 9 to 15 nJ, respectively, depending on the operating regimes of the master oscillator and amplifier.