High-Order Modes Suppression in All-Glass Large-Mode Area Rare-Earth Doped Optical Fibers with Modified Cladding

In the present work we have developed and realized a high core-to-cladding diameters ratio active optical fibers operated in a single-mode regime due to specially designed structure containing boron-doped and fluorine-doped rods. The beam quality at the output of the realized fibers was studied by three independent methods: near field investigation, M2 technique and S2 technique. According to the obtained results, the developed approach allows efficient suppression high-order-modes (first of all—LP11 mode) in the core and achieves a diffraction-limited beam at the output of the appropriately bent fiber (suppression of unwanted modes was better than 30 dB). Additionally, it is shown that application of such approach allows for increased bent-resistance of the fundamental mode and realizes polarization-sensitive amplification

Er-Doped Tapered Fiber Amplifier for High Peak Power Sub-ns Pulse Amplification

A tapered Er-doped fiber amplifier for high peak power pulses amplification has been developed and tested. The core diameter changed from 15.8 µm (mode field diameter (MFD) 14.5 µm) to 93 µm (MFD 40 µm) along 3.7 m maintaining single-mode performance at 1555 nm (according to the S2-method, the part of the power of high-order modes does not exceed 1.5%). The amplification of 0.9 ns pulses with spectral width below 0.04 nm up to a peak power above 200 kW (limited by self-phase modulation) with a slope pump-to-signal conversion efficiency of 15.6% was demonstrated

Er-Doped Tapered Fiber Amplifier for High Peak Power Sub-ns Pulse Amplification

A tapered Er-doped fiber amplifier for high peak power pulses amplification has been developed and tested. The core diameter changed from 15.8 µm (mode field diameter (MFD) 14.5 µm) to 93 µm (MFD 40 µm) along 3.7 m maintaining single-mode performance at 1555 nm (according to the S2-method, the part of the power of high-order modes does not exceed 1.5%). The amplification of 0.9 ns pulses with spectral width below 0.04 nm up to a peak power above 200 kW (limited by self-phase modulation) with a slope pump-to-signal conversion efficiency of 15.6% was demonstrated

Narrow-Linewidth Diffraction-Limited Tapered Er-Doped Fiber Amplifier with 2 mJ Pulse Energy

The possibility to scale-up output pulse energy in diffraction-limited Er-doped fiber amplifier has been studied. It is shown that the utilization of tapered fiber design allows one to increase the pulse energy up to 2 mJ, while keeping the diffraction-limited beam quality (M2~1.4). Factors limiting the further increase in pulse energy are revealed

Polarization-maintaining photonic bandgap Bragg fiber

International audienceThe possibility of fabricating a polarization-maintaining Bragg fiber has been studied. It is shown that violation of the cylindrical symmetry of a Bragg mirror in most cases results in a sharp increase in optical loss, which is caused by resonance transmission through the Bragg mirror at wavelengths near the cutoffs of the modes of the high-index rings with a nonzero azimuthal index. It is shown that placing stress-applied parts or air holes inside the Bragg fiber core allows one to avoid this effect. A polarization-maintaining Bragg fiber with perfect light confinement in the core is demonstrated for the first time to our knowledge

Polarizing Very-Large-Mode-Area Bragg fiber

International audienc

Millijoule pulse energy 100-nanosecond Er-doped fiber laser

International audienceWe report, for the first time to our knowledge, on a single-mode millijoule-level 100-nanosecond Er-doped fiber laser operating near 1550 nm. The system features a newly developed 35-μm-core Yb-free double-clad Er-doped fiber based on P2O5-Al2O3-SiO2 glass matrix and produces pulses with energy as high as 1 mJ at repetition rates of 1–10 kHz