2 MW peak power generation in fluorine co-doped Yb fiber prepared by powder-sinter technology

Abstract

We report on the first, to the best of our knowledge, implementation of a fluorine co-doped large-mode-area REPUSIL fiber for high peak power amplification in an ultrashort-pulse master oscillator power amplifier. The core material of the investigated step-index fiber with high Yb-doping level, 52 µm core and high core-to-clad ratio of 1:4.2 was fabricated by means of the REPUSIL powder-sinter technology. The core numerical aperture was adjusted by fluorine codoping to 0.088. For achieving high beam quality and for ensuring a monolithic seed path, the LMA fiber is locally tapered. We demonstrate an Yb fiber amplifier with near-diffraction-limited beam quality of M 2 = 1.3 , which remains constant up to a peak power of 2 MW. This is a record for a tapered single core fiber.

High‐Power Laser Systems

“…Tapered fiber opens a new way for high‐power fiber amplifiers. At present, it has been adopted in kW‐level all‐fiber resonators, [ 410 ] MOPA amplifiers, [ 411 ] MW‐level CPA‐free amplification, [ 409,412 ] and high‐power single‐frequency (SF) laser output. [ 413,414 ]…”

Tapered Multicore Fiber for High-Power Laser Amplifiers

“…The possibility of creating a completely monolithic amplifier and laser with a fiberized injection of pump radiation into the tapered fiber is demonstrated [18]. Peak powers of a megawatt level are demonstrated [14], [15], [16], [17], which are comparable in order of magnitude with the self-focusing limit in silica. At this, up to several tens of MW after compression is shown [15], [19] when using chirped pulse amplification.…”

“…A specific feature of tapered fibers is the relative simplicity of the structure of their cores (in fact, the step-index profile can be used) and the possibility of a completely monolithic structure, as well as the simplicity of implementing a structure with a double cladding for injection of pump radiation [9]. High-power laser systems of the kilowatt level [10] with good beam quality [11], [12], high energy Q-switched pulsed lasers [13] and ultrashort pulse amplifiers [14], [15], [16], [17] are demonstrated using tapered fibers. The possibility of creating a completely monolithic amplifier and laser with a fiberized injection of pump radiation into the tapered fiber is demonstrated [18].…”

Ultra-low NA step-index large mode area Yb-doped fiber with a germanium doped cladding for high power pulse amplification

“…Furthermore, use of PCFs poses various practical difficulties in terms of fiber fabrication, fiber handling and integration into all-fiber laser systems. Very recently, an alternative approach, the use of tapered optical fibers, has been introduced and extensively investigated [13][14][15][16][17][18]. Here, a LMA step-index fiber is tapered over its length, with the tapered end used as the signal input end to ensure fundamental mode coupling and the amplified signal output is coupled from the other larger core end.…”

“…Alternatively, the fiber tapering process can be introduced using a flame brushing technique after the fiber draw. An adiabatically tapered amplifier of <1 m length was used to generate 2 MW peak power pulses [18], but this requires special adaptations and precautions to realize long fiber tapers (i.e.. stripping, cleaning, tapering and recoating of a very long fiber) and leads to unwanted effects such as dopant diffusion and index profile modifications [17,18]. Recently, we have reported a very high absorption step-index Yb-doped LMA fiber made using the conventional modified chemical vapor deposition (MCVD) process combined with the solution doping technique [19].…”