Experimental Demonstration of a Ring-Cavity Q-Switched Fiber Regenerative Amplifier

Abstract

The static and dynamic magnetic behaviour of Fe nanoclusters with controlled sizes in the range 140-270 atoms (1.5-1.8 nm) deposited in situ from a gas aggregation source on magnetic vitrovac amorphous ribbons has been studied using synchrotron radiation. The static magnetization of the cluster films in the exchange field of the substrates was measured as a function of coverage using magnetic linear dichroism in the angular distribution (MLDAD) of the Fe 3p core level photoemission. The switching dynamics were studied on the nanosecond timescale by time-resolved spin-polarized photoemission. For a given particle size, the magnetization of the Fe cluster film increases with coverage and saturates at a coverage of about 0.4 cluster monolayers. Modelling the growth of the magnetization gives an effective exchange field at the interface of ∼20 T. Dense cluster films with several cluster layers have an MLDAD signal at saturation that is ∼5% higher than a molecular beam epitaxy (MBE)grown film, indicating an enhanced spin moment even when clusters are in contact. Coating an exposed sub-monolayer cluster layer with Co increases the Fe MLDAD signal by 35%, indicating a substantially increased magnetic moment within the Fe clusters. At low coverages, below the percolation threshold, the switching dynamics of the sample remains the same as in the clean substrate. At around the percolation threshold, however, a significant acceleration of the magnetic reversal is observed with a fast component due to a reversal propagating through the cluster film. We show that, on average, each cluster switches in about 10 ns.

Regenerative Er-doped Fiber Amplifier System for High-repetition-rate Optical Pulses

“…Pumping above a certain threshold can lead to self-oscillation in the amplifier. This kind of regenerative amplifier can easily achieve the high repetition rate pulse regenerative amplification relative to the other kind of regenerative amplifier that has an optical switch in the amplifier like ref [13][14][15][16]. This type of regenerative amplifier technique can also be applied to the other rare-doped fiber amplifier systems such as Yb and Tm.…”

“…The pump power is under the self-lasing threshold. The second kind has an optical switch in the amplifier [13][14][15][16]. The usage of an optical switch provides some flexibility to amplify high-repetition-rate pulses.…”

“…So it is necessary to investigate the pulses amplification of this kind of regenerative amplifiers. Later, the second kind of regenerative amplifier for Q-switched pulses with low repetition rate and nanosecond pulse width have also been investigated [13][14][15][16]. In contrast to the first kind, the second kind of regenerative amplifier is of optical switch, such as AOM.…”

“…The structure of regenerative amplifiers is different from the regenerative amplifiers described in ref [9][10][11][12]. In 2006, Yang demonstrated an all-fiber-based ring-cavity Q-Switched regenerative Erdoped amplifier that achieved 40 dB gain and 30nJ output pulse energy at 1.53 μm [13]. In 2009, a photonic crystal fiber-based regenerative amplifier at 1078 nm was reported [14].…”

High-gain all-fiber regenerative amplifier

“…In addition, all-fiber regenerative amplifiers can easily operating at saturation which can enhance the output stability a lot. In 2006, Yang [5] reported a ring cavity, Q-switched fiber regenerative amplifier that achieved 40-dB gain and 30-nJ output pulse energy at 1 530 nm. Recently Xin et al [6] demonstrated a Yb-doped all-fiber regenerative amplifier operating at 1 053 nm amplified 10-ns, 15-pJ square pulses to 240 nJ.…”