Power scaling of narrowband high-power all-fiber superfluorescent fiber source to 187  kW

Abstract

We demonstrate a high-power narrowband all-fiber superfluorescent fiber source employing three-stages master oscillator power-amplifier chain. Narrowband seed light is selected from a broadband-amplified spontaneous-emission source by a spectrum filter combing with fiber circulator and fiber Bragg grating. In the main amplifier, the maximal output power is 1.87 kW with an optical-to-optical conversion efficiency of 77.4% and a full width at half-maximum (FWHM) linewidth of 1.7 nm. The corresponding power fluctuation is ±1.4% in 100 s operation, and no parasitic oscillation or self pulsation is observed. A beam quality of M(2)=1.71 is measured at 1.4 kW output power. This manuscript investigates the spectral evolution in high-power amplification. The central wavelength shifted from 1079.5 nm to 1080.7 nm, and the FWHM linewidth narrowed from 2 nm to 1.7 nm at full power, respectively. These effects could be inferred as hybrid effects of many factors, such as wavelength shifting of pump LD, nonoptimized length of gain fiber, and enhancement of temperature level of gain fiber. The narrowband-maintained characteristic in spectral domain under high-power amplification is significant for applications such as spectral beam combination, and further power scaling is available as the output power is only limited by the pump power.

In-band pumping avenue based high power superfluorescent fiber source with record power and near-diffraction-limited beam quality

“…Furthermore, the FWHM linewidth broadens to about 4.68 nm, which is different from the previously reported narrowband MOPA-structured spectral-broaden-free SFS in Ref. [29] pumped by the LD. As the linewidth broadening is mainly induced by the generation of nonlinear effects [41] , such as self-phase modulation (SPM) and cross-phase modulation (XPM), the difference may be induced by the relative long gain fiber employed in this scheme.…”

“…What is more, the presented high power SFSs in single-stage structure were often broadband and randomlypolarized [16][17][18][19] , while narrowband and polarization characteristics are required in practical applications [20,21] . Fortunately, employing master-oscillator-power-amplifier (MOPA) configuration can introduce a new horizon of high power SFS and leverage the high power SFS with special spectrum/polarization characteristics [22][23][24][25] and kilowatts operating power [26][27][28][29][30] . Besides, the output light of MOPAstructured SFS, in contrast to that of fiber MOPA seeded by standard resonant-cavity-based oscillator with self-pulsing effect, also has the advantages of high temporal stability [2,4] .…”

High Power Linearly Polarized Raman Fiber Laser With Stable Temporal Output

“…As shown in Fig. 1, the ASE pump source consists of a homemade broadband ASE seed source [31] and two-stage polarization-maintaining (PM) power amplifiers, the central wavelength of which is about 1074.8 nm, with full width at half maximum (FWHM) linewidth ~10.3 nm at the maximum pump power. A PM isolator (ISO) is adopted to extract linearly polarized ASE source.…”

High power all-fiberized and narrow-bandwidth MOPA system by tandem pumping strategy for thermally induced mode instability suppression

“…As for SBS effect, some effective approaches had been proposed to mitigate its influence over the past decade. These approaches mainly include incorporating thermal and longitudinal stress gradients [11][12][13] , using counterpropagating pump [14] , special transverse-designed active fiber [12,15] , multi-longitudinal-mode fiber oscillator [16,17] , filtered super-fluorescent source [10,18] , multi-wavelength injection and laser gain competition [19,20] and applying phase modulation technique [8,9,[20][21][22][23][24][25][26][27][28][29] . Within these SBS management approaches, phase modulation technique is a preferable approach beyond the output power of multikilowatt level [22][23][24][25][26][27][28][29] .…”