Investigations of a 1018 nm gain-switched Yb-doped fiber oscillator.

In this paper, we investigate a 1018 nm gain-switched ytterbium-doped fiber oscillator at a low repetition rate in terms of theory and experiment. Theoretically, a numerical model applicable to a 1018 nm gain-switched ytterbium-doped fiber laser was established. The influence of the pump peak power and active fiber lengths on the 1018 nm gain-switched ytterbium-doped fiber laser was numerically simulated.

All-fiber hectowatt radially polarized laser system.

A high-power all-fiber radially polarized laser system is demonstrated, in which an integrated nanograting mode convertor (S-wave plate) is used for the generation of radially polarized beam. Experimentally, a 1-W radially polarized beam was used as the seed laser, whose mode purity and mode extinction ratio (MER) were 96.5% and 98.

Coherent beam combining of cylindrical vector beams for power scaling.

Coherent beam combining (CBC) of cylindrical vector beams (CVBs) based on an active phase controller is proposed and demonstrated. Experimentally, two pieces of spatially variant wave plates (S-wave plate) were employed as vector mode convertors for two individual 1064-nm fiber amplifier channels. When the system was in a closed loop, a combined output power of 10 W and a CBC efficiency of higher than 94% were achieved, for both TM (radially polarized) mode and TE (azimuthally polarized) mode cases.

Nonlinear spectral compression in high-power narrow-linewidth polarization maintaining fiber amplifiers for SBS suppression.

In this paper, we propose a method for narrowing the spectrum in high-power narrow-linewidth polarization-maintaining (PM) fiber amplifiers and investigate its potential for suppressing the stimulated Brillouin scattering (SBS). In this method, in addition to common phase modulation to suppress SBS, precisely designed amplitude modulation is induced to generate self-phase modulation in a high-power PM fiber amplifier. In this co-modulation way, the spectrum can be gradually compressed along the fiber.

Linearly polarized fiber amplifier with narrow linewidth of 5 kW exhibiting a record output power and near-diffraction-limited beam quality.

In this work, a narrow-linewidth polarization-maintaining (PM) all-fiber amplifier with near-diffraction-limited beam quality and record output power is presented. First, a 4.45-kW PM fiber amplifier with a 3-dB linewidth of 0.

High-power narrow-linewidth fiber lasers using optical spectrum broadening based on high-order phase modulation of inversion probability-tuning sequence.

Continuous fiber laser with ultra-high power and narrow linewidth is one of the key devices in the field of high-precision industrial processing, beam combining, and nonlinear frequency conversion. Under the premise of ensuring the signal quality, continuously increasing the output power is the focus of high-power narrow-linewidth fiber lasers. Driven by the white noise or pseudo-random binary sequence (PRBS), using cascaded phase modulations to broaden the spectrum of the seed source to suppress the stimulated Brillouin scattering (SBS) effect in the master oscillator power amplifier (MOPA) structure is an effective solution to increase the output power.

3.25 kW all-fiberized and polarization-maintained Yb-doped amplifier with a 20 GHz linewidth and near-diffraction-limited beam quality.

In this paper, we demonstrate a high-power, narrow-linewidth, polarization-maintaining fiber amplifier with near-diffraction-limited beam quality. By optimizing the phase modulation signal, a nearly top-hat-shaped spectrum was generated for self-pulsing suppressing. That results in doubling the self-pulsing threshold we got from conventional white noise signal phase modulation with the same optical linewidth.

1.5 kW polarization-maintained Yb-doped amplifier with 13 GHz linewidth by suppressing the self-pulsing and stimulated Brillouin scattering.

In this work, we study the characteristics of self-pulsing in a polarization-maintained fiber amplifier operated with different linewidths based on white noise source phase modulation. It indicates that the self-pulsing is almost simultaneous with the stimulated Brillouin scattering process, and its threshold is increasing near-linearly with the linewidth. By optimizing the laser structure, the threshold of self-pulsing increases by a factor of 1.

[Research progress on quality control methods of traditional Chinese medicine glues].

Traditional Chinese medicine( TCM) glues,including leather glues,horn glues,nail glues and bone glues,have a long application history and unique characteristics. In recent years,their market demand has increased year by year because of their remarkable curative efficacy and nourishing effects,which leads to insufficient supply of raw material resources,and widespread use of fake and inferior products,seriously affecting the reputation of TCM glues and drug safety. In this context,the establishment of a more specific quality detection method for the TCM glues according to their specific characteristics can effectively improve the quality control level,promote rational use,and have a far-reaching impact on the industrial development of TCM glues.

Self-pulsing in kilowatt level narrow-linewidth fiber amplifier with WNS phase-modulation.

The self-pulsing phenomenon in kilowatt level narrow-linewidth fiber amplifiers with white noise source (WNS) phase-modulation is observed experimentally. It possesses the obvious threshold of the pump power and prevents the narrow-linewidth fiber lasers from further power scaling. The experimental study shows that known explanations are not applicable here and indicates that occurrence of self-pulsing is closely related to Stimulated Brillouin Scattering (SBS) process.

6.5 GHz linearly polarized kilowatt fiber amplifier based on active polarization control.

The polarization-dependent transverse mode properties in a few-mode nonpolarization-maintaining (non-PM) fiber amplifier with PM fiber laser seeding are investigated. In addition, the effect of spectral broadening on degeneration of the degree of polarization (DOP) is studied. The experimental results show that a high DOP can be achieved if the output laser of the non-PM fiber amplifier has good beam quality and a narrow linewidth without any broadening.

High-efficiency, high-average-power, CW Yb:YAG zigzag slab master oscillator power amplifier at room temperature.

We demonstrate a high-efficiency, high-average-power, CW master oscillator power amplifier based on a conduction-cooled, end-pumped Yb:YAG slab architecture at room temperature (RT). Firstly, the CW amplification property is theoretically analyzed based on the kinetics model for Yb:YAG. To realize high-efficiency laser amplification extraction for RT Yb:YAG, not only intense pump but also a high-power seed laser is of great importance.