The rise in output power from rare-earth-doped fiber sources over the past decade, via use of cladding-pumped architectures, has been dramatic, leading to a range fiber-based devices with outstanding performance terms power, beam quality, overall efficiency, and flexibility regard operating wavelength radiation format. This success high-power arena is largely due fiber's geometry, which provides considerable resilience effects heat generation core, facilitates efficient conversion relatively...

We have demonstrated a highly-efficient cladding-pumped ytterbium-doped fiber laser generating 1.36 kW of continuous-wave output power at 1.1 mum with 83% slope efficiency and near diffraction-limited beam quality. The was end-pumped through both ends showed no evidence roll-over even the highest power, which limited only by available pump power.

The ytterbium-doped fiber amplifier offers a number of attractive features, including broad-gain bandwidth and high efficiency, due in large part to its freedom from various competing processes seen other rare-earth dopants. Here we discuss the main features that influence design possible applications amplifiers.

The brightness, robustness, and flexibility of high-power fiber laser sources provide an enabling technology for science industry.

We discuss continuous-wave single-frequency master- oscillator power-amplifier (MOPA) sources based on ytterbium- doped fibers (YDFs) with particular attention to their recent advances and our experimental results. This includes a 402-W plane-polarized MOPA source 511-W random-polarized source. In these MOPAs, the final-stage high-power amplifier operates high efficiency of 70%-80%, gain over 20 dB in near diffraction-limited beam. report at least 7-dB enhancement stimulated Brillouin...

We have demonstrated a high-power and high-efficiency erbium:ytterbium (Er:Yb) codoped fiber laser that produces 297 W of continuous-wave output at 1567 nm. The slope efficiency with respect to the launched pump power changed from 40% 19% higher due onset Yb colasing 1067 However, was essential for suppression catastrophic pulsation high powers otherwise results if Yb-band gain is allowed build up. Spectroscopic characteristics impact on 1567-nm are also discussed.

We have demonstrated a highly efficient cladding-pumped ytterbium-doped fiber laser, generating <TEX>$&gt;$</TEX>2.1 kW of continuous-wave output power at 1.1 μm with 74% slope efficiency respect to launched pump power. The beam quality factor (<TEX>$M^2$</TEX>) was better than 1.2. maximum only limited by available power, showing no evidence roll-over even the highest present data on how depends parameter, based our current and past laser developments. also discuss ultimate power-capability...

We report on a Q-switched, cladding-pumped, ytterbium-doped large-mode-area fiber laser operating at 1090 nm that is capable of generating 2.3 mJ output pulse energy 500-Hz repetition rate and more than 5 W average power higher rates in high-brightness beam M2=3. Using similar with smaller core, we generated >0.5‐mJ pulses diffraction-limited beam. Our results represent threefold increase over previously published values for Q-switched lasers firmly establish as compact, multiwatt,...

We propose and theoretically analyze three-level cladding-pumped fiber lasers in which the laser-active dopant is placed a ring around single-mode core. A ring-doped laser can work efficiently at wavelengths with strong small-signal absorption. This otherwise difficult fiber. Moreover, doping makes less sensitive to quenching of excited-state absorption lasing field. In simulations Yb3+-doped laser, increased slope efficiency 62%, up from 13% for conventional core-doped

Eight different fibers were studied to examine upconversion as a function of erbium concentration below 1000 ppm by weight. These experiments and computer model two-particle made it possible estimate the coefficient used in rate-equation model. A strong correlation was found between amplification reduction parasitic with both Ge- Ge/Al/P-cores when erbium-doping is range 70-840 When plotting maximum versus 980 luminescence on logarithmic scale, slope approximately -2 irrespective host...

A ytterbium-doped fibre laser with up to 1 kW of continuous-wave output power at 1.09 µm a slope efficiency 80% and good beam quality (M2=3.4) is reported. The was pumped by two diode-stack sources launched through opposite ends. No undesirable roll-over observed in increasing pump power.

Photodarkening of Yb-doped aluminosilicate fibers by continuous wave 488nm irradiation was investigated. The induced significant excess loss in the UV-visible spectroscopy (VIS) region while pure showed negligible loss. Ultraviolet-VIS-near-infrared revealed an absorption peak at 220nm unexposed fiber preforms. observed attributed to Yb-associated oxygen deficiency centers (ODCs) and proposed as a precursor photodarkening. model supported measurements on oxygen-loaded fibers. In these,...

We have fabricated an ytterbium doped all-glass double-clad large mode area holey fiber. A highly efficient cladding pumped single transverse fiber laser has been demonstrated, allowing continuous-wave output powers in excess of 1W with efficiencies more than 80%. Furthermore both Q-switched and mode-locked operation the demonstrated.

A high-power double-clad Tm-doped silica fiber laser, pumped by two beam-shaped and polarization-coupled diode bars at 787 nm, was wavelength tuned use of an external cavity containing a diffraction grating. The Tm laser produced maximum output power 7 W 1940 nm for 40 incident over range 230 from 1860 to 2090 with >5-W the 1870-2040 nm. prospects further improvement in performance extension tuning are discussed.

We present a single-frequency, single-mode, plane-polarized ytterbium-doped all-fiber master oscillator power amplifier source at 1060 nm generating 264 W of continuous-wave output power. The final-stage operated with high gain 19 dB and conversion efficiency 68%. There was no evidence rollover from stimulated Brillouin scattering even the highest power, maximum limited only by available pump

We demonstrate active pulse shaping using an Electro-Optic Modulator in order to compensate the effects caused by Gain Saturation a high power Yb doped fiber amplifier chain and generate various custom-defined output shapes. Square, step smooth shapes are achieved, with mJ energies. Use of modulator shape pulses rather than direct modulation diode drive current allows us eliminate undesired transients due laser start up dynamics. The required is calculated based on simple measurement...

We demonstrate a pulsed ytterbium-doped fiber master-oscillator power amplifier source at 1060 nm producing over 300 W of average in 20-ps pulses 1-GHz repetition rate. The generated by gain-switched diode were compressed chirped Bragg grating and amplified without any distortion with excellent spectral quality. This master oscillator system offers versatility potential for further scaling.

We describe novel fiber Raman lasers pumped directly by spectrally combined high power multimode laser diodes at ~975 nm and emitting ~1019 nm. With a commercial graded-index fiber, we reached 20 W of output with record slope efficiency 80%. an in-house double-clad the beam quality improved to M2 = 1.9, albeit lower due higher loss. believe this is first publication cladding-pumped diodes.

Coherent beam combination of multiple fibres can be used to overcome limitations such as the power handling capability single fibre configurations. In a scheme, focal intensity profile is critically dependent upon relative phase each and so precise control over channel essential. Determining required compensations from alone (as measured via camera) extremely challenging with large number information obfuscated. Whilst iterative methods exist for retrieval, in practice, due noise within...

Abstract. Antarctica's floating ice shelves modulate discharge of grounded into the ocean by providing a backstress. Ice shelf thinning and grounding line retreat have reduced this backstress, driving rapid drawdown key unstable areas Antarctic Sheet, leading to sea-level rise. If loss continues, it may initiate irreversible glacier through marine sheet instability. Identification undergoing significant change requires knowledge spatial temporal patterns in recent loss. We used 26 years...

Fabrication process of efficient Yb/sup 3+/,Er/sup 3+/ codoped phosphosilicate fibers by modified chemical vapor deposition (MCVD) combined with the solution doping technique is studied in detail. We show that can be adapted to incorporate low viscosity phosphate glass and some important issues fabrication are discussed. These include sensitive presintering pass. also report on a loss all-glass double clad 3+/:Er/sup fiber. explain how we evaluate discuss effect ytterbium erbium...

Efficient repetitive passive Q switching of a cladding-pumped Er–Yb fiber laser has been demonstrated by use an external-cavity configuration containing Co2+:ZnS crystal as saturable absorber. Energies much 60 µJ in pulses durations short 3.5 ns (FWHM), corresponding to peak power >10 kW, have generated, and the maximum slope efficiency with respect absorbed pump was 13%. Using bulk diffraction grating Littrow provide wavelength-selective feedback, we tuned passively Q-switched over 31 nm...

We present a cladding-pumped single-frequency, single-mode erbium:ytterbium codoped fiber master-oscillator power amplifier source generating up to 151 W of continuous-wave output at 1563 nm with 33% slope efficiency and 20 dB gain. This was also tunable had stable operation range 1546to1566 an level in excess 125 W. The doped exploited large-core design for improved handling mitigation stimulated Brillouin scattering. There no sign having scattering even the highest power. Despite large...