High power linearly polarized narrow linewidth fiber laser

Abstract

Spectral beam combining technology based on diffraction grating is an effective method to obtain tens of thousands of watts or even hundreds of thousands of watts of high-power and high beam quality laser. The high power linearly polarized narrow linewidth fiber laser is an ideal sub-beam source in spectral beam combining systems. Limited by stimulated brillouin scattering and mode instability, the power increase of narrow linewidth lasers has been limited, especially in linear polarization systems. In this paper, we report a high-power line polarized narrow line width fiber laser. The white noise signal (WNS) phase modulation and the pseudo-random binary sequence (PRBS) phase modulation were combined to widen the single-frequency laser line width, and then the three-stages fiber amplifier was used to amplify the narrow-line width laser for power, A high power line polarized narrow line width laser with a center wavelength of 1064nm, a power of 2070W and a 3dB line width of 23GHz was finally obtained. The laser polarization extinction ratio is greater than 14dB.

Analysis of Constraints on the Remote Application of Inverse Synthetic Aperture Laser Radar

“…The narrower the linewidth, the better the coherence. From a simple linear fitting of five groups of power and linewidth data points [9] in the research progress of 1064 nm fiber lasers, the results are shown in Figure 6 (the fitting only describes the rough relationship between laser power and coherence. In reality, it is not an ideal linear relationship.…”

“…In addition, because the power required for remote target detection has reached the order of kilowatts (kW) or even gigawatts (GW), which is much higher than the power level that can be achieved in China at present, the laser will also produce nonlinear effects while achieving high power. For example, SBS (stimulated Brillouin scattering) is more likely to occur when the linewidth is narrow, SRS (stimulated Raman scattering) is more likely to occur when the linewidth is wide, and LMI (lateral mode instability) is more likely to occur when the optical fiber core mode field diameter is too large [9]. Therefore, a single-mode fiber with a length of 1 m, a mode field diameter of 30 µm, and an attenuation coefficient of 0.4 dB/km are selected [9].…”

“…For example, SBS (stimulated Brillouin scattering) is more likely to occur when the linewidth is narrow, SRS (stimulated Raman scattering) is more likely to occur when the linewidth is wide, and LMI (lateral mode instability) is more likely to occur when the optical fiber core mode field diameter is too large [9]. Therefore, a single-mode fiber with a length of 1 m, a mode field diameter of 30 µm, and an attenuation coefficient of 0.4 dB/km are selected [9]. Based on the single-frequency narrow linewidth characteristics of ISAL lasers, fiber lasers are more susceptible to SBS.…”

“…Based on the single-frequency narrow linewidth characteristics of ISAL lasers, fiber lasers are more susceptible to SBS. Through literature research, the relationship between the threshold power of SBS and the linewidth of the laser [9] is depicted in Equation ( 6).…”

“…However, the narrower the laser linewidth, the more susceptible the laser power increase is to nonlinear effects, especially the stimulated Brillouin scattering (SBS), resulting in limited laser power. At the same time, the presence of nonlinear effects can also lead to the broadening of the laser linewidth, resulting in turn in reduced coherence [9]. Therefore, this paper will focus on studying the relationship between the two primary constraints of ISAL (space-based) remote applications-laser power and coherence-and try to provide a solution for the remote application of optical path difference compensation.…”