The effective pumping factor for various Laser Diodes (LDs) is defined to explain the absorption characteristic of wavelength-stable LDs (WS-LDs). This factor is used to determine wavelength locking points and residual pump power. We evaluated the wavelength locking ability and residual pump power in quantity using two groups of comparable LDs and a narrow linewidth fiber laser. Prior to running LDs in a fully wavelength-locked state, the maximum residual pump power is observed at low pump power levels. This information can be useful in engineering applications for establishing appropriate cooling standards for CPS heat load. Additionally, it is valuable for WS-LD manufacturers to provide a universal evaluation factor for assessing different LDs and guiding wavelength locking quantity enhancement.
The influence of mode instability (MI) on polarization extinction ratio (PER) has been investigated in a 2 kW level polarization-maintained (PM) fiber laser system with backward-pumped configuration, and the phenomena is different from the existing observation in forward-pumped PM fiber amplifiers. During the experiment, with the onset of MI, none decrease of PER has been observed, revealing that the MI effect has little impact on PER in backward PM fiber amplifiers. The discrepancy induced by the pump configuration has been theoretically analyzed, and the origin is attributed to the longitudinally-distribution difference of high order mode induced by the MI effect.
In this work, a high-power polarization-maintained fiber laser with ultra-narrow linewidth and near diffraction limited beam quality is demonstrated. The stimulated Brillouin scattering is mitigated by optimizing phase modulation scheme, the mode instability is suppressed by coiling the active fiber, and the output power reaches to 3kW at the full width at half-maximum linewidth of 10.6GHz. At maximum output power, the stimulated Raman scattering suppression ratio reaches to 75dB, the polarization extinction ratio is 96%, the beam quality M2 is 1.156, and the further scaling of output power is limited by stimulated Brillouin scattering effect. To the best of our knowledge, this is the highest power for polarization-maintained fiber laser with about 10GHz linewidth ever reported so far.
1090 nm all-fiberized and Polarization-maintained fiber laser with narrow linewidth and near-single-mode beam quality is demonstrated. We obtain a 668 W narrow linewidth linearly laser output with a linewidth of about 22GHz, the polarization extinction ratio is about 14dB, and the M2 is less than 1.1 at the maximum output power.
This paper comprehensively considers the suppression effect of fiber parameter control on Stimulated Brillouin Scattering (SBS), and studies the influence of different phase modulation modes, different linewidths, different fiber Yb ion densities, and different fiber lengths on the SBS threshold of the whole system, The best system setting scheme for improving SBS threshold is also given.
The coherent beam combination of kW fiber lasers with a filling aperture has been in research. An experiment is set up to achieve the coherent beam combination. The coherent beam combination of two fiber lasers with a filling aperture is realized, and the phase bandwidth of the beam combination is measured and analyzed. The laser spots before and after the combination are detected respectively. The phase noise of high power laser is measured and the factors affecting the phase noise are analyzed.
The stimulated Brillouin scattering (SBS) effect in fiber amplifiers using white noise signal (WNS) phase modulated seed is simulated. The influences of cut-off frequencies of WNS and the output fiber structure on SBS threshold are discussed. Basing on simulation results, optimized phase modulation signal and output fiber structure are achieved to suppress SBS. A fiber laser is established according to the simulation results.
In this paper, we report the experimental study on stimulated Raman scattering (SRS) induced mode instabilities (MI) in large mode area step-index fiber in a counter-pumped all-fiberlized amplifier. When the output power is scaled to 1560W, the ratio of SRS is 2% and the beam quality factor M2 is about 1.4. With the further scaling of output power, the SRS power begins to increase nonlinearly, and then the beam quality degrades obviously when the ratio of SRS exceeds 3%, and the M2 is about 2.1 at 1910W, that is the SRS induced MI. The phenomenon is accompanied by the temperature increasing of output passive fiber, which is caused by heat deposition of quantum defect between signal light and Raman light. The temporal dynamics of SRS induced MI is studied in detail for the first time, which are characterized by using both camera measurement and photodiode traces. The experiment results express that both the output power and output beam profile remain stable before the MI occurs, and fluctuate obviously after the onset of SRS induced MI. The temporal frequency investigation indicates that the SRS induced MI is a dynamic process with slow speed fluctuation at second level, and the Fourier spectrum of time trace is within 10Hz, and the SRS induced mode degradation is different from the Yb-gain induced MI effect.
In this paper, the model to simulate the impact of bend induced mode distortion on the beam quality and mode instability (MI) threshold of fiber amplifier is established, and the results show that the bend induced mode distortion will degrade the beam quality of fiber laser and decrease the MI threshold. The bend induced mode distortion will change the gain of active fiber, then destroy the beam quality of fiber amplifier, and decrease the MI threshold, but the bend loss will suppress high order mode. Therefore, with the decreasing of fiber bend radius, the MI threshold will decrease firstly, and then increase.
In this manuscript, a 3.53kW average output power all-fiber laser system at 1064nm with 3dB linewidth as narrow as 0.16nm and near single-mode beam quality (M2 ≈1.7) is demonstrated. There is no obvious stimulated Brillouin scattering, stimulated Raman scattering or amplified spontaneous emission observed. To the best of our knowledge, this is the highest output power of all-fiber laser system with narrow-linewidth and near single-mode beam quality ever reported.
A high power 1030 nm ytterbium-doped polarization maintained fiber laser with optimized parameters is presented in this paper. The master oscillator power amplifier system with counter-pumped amplifier is established. The output power is 900 W, along with a light-to-light efficiency of 64.2%. The amplified spontaneous emission suppression ratio of spectrum reaches to 40 dB with 3 dB linewidth of 0.14 nm. The polarization extinction ratio is 12 dB, and the beam quality factor is M2x=1.07, M2y=1.12. To the best of our knowledge, this is the first demonstration of 1030 nm high power fiber laser with narrow linewidth, near linear polarization, and neardiffraction-limited beam quality
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.