All-fibre single-mode small-signal amplifier operating near 0.976 μm

Abstract

We have developed and demonstrated a polarisation-maintaining single-mode ytterbium-doped fibre for light amplification at a wavelength near 0.976 μm in an all-fibre configuration. A distinctive feature of the proposed fibre design is low losses due to fusion splices with standard single-mode fibre having a core diameter of 10 μm, which has made it possible to produce an all-fibre small-signal amplifier with a gain threshold near 3 W and a differential pump-to-signal conversion efficiency of 9.8 % in the saturation regime. The proposed amplifier has been shown to be well-suited for small-signal amplification. In particular, at an input signal power near 1 mW and a gain of 20 dB, the ratio of the amplified signal to the integrated luminescence intensity near 0.976 μm exceeds 20 dB. A 40-dB gain has been demonstrated for an ultrasmall signal of ∼10-μW power.

Improvement of Efficiency in 976 nm Fiber Amplifier by Spectral Filtering in Yb-Doped Fiber with Absorbing Rods Embedded in the Cladding

“…At the same time, the increase of the output signal was rather small, about 10-30% depending on the pump power (see Figure 5). Additionally, the overall efficiency near 10% was still small, and it was comparable to the results obtained in fiber with a ring-doping design, in which no suppression of ASE at 1030 nm was realized [6]. In fact, the main objective of the current work was to test a novel approach to increase PCE in fiber amplifiers that operate near 976 nm and to reveal factors, which limits the applicability of the current method.…”

“…We suggest that it might be due to the non-uniform broadening of the Yb 3+ absorption band near 976 nm. This effect was previously observed in [5,6], and in [5], it was suggested that it could be a reason for the decrease in efficiency in fiber amplifiers (compared to the free-running fiber lasers). In the current work, our aim was to estimate the influence of Yb concentration on PCE; thus, we compared only the relative change in efficiency, keeping in mind that the real efficiency could be somewhat smaller.…”

“…The reason for this is that, for short-wavelength operation (near 976 nm), it is necessary to suppress the amplified spontaneous emission (ASE) near 1030 nm, which typically has the lowest lasing threshold in standard fibers. There are plenty of works regarding this topic to date [1][2][3][4][5][6][7][8]. The most promising results so far have been demonstrated by fabricating a short-pass filter based on the rather complicated Photonics Bandgap Fiber design [4,5].…”

An Ytterbium-Doped Narrow-Bandwidth Randomly Distributed Feedback Laser Emitting at a Wavelength of 976 nm

“…For this reason, specially designed active fibers are used to achieve an acceptably high pumpto-signal conversion efficiency. In particular, this goal can be achieved by introducing excessive optical losses into the spectral region of 1030 nm [12,13], or by creating fibers with an increased ratio of the area of the core to the cross-section area of the first reflective cladding [14][15][16][17][18].…”

Yb-волоконные лазеры, излучающие в спектральном диапазоне около 0.98 мкм

“…Кроме того, использование в схемах световодов с увеличенным размером сердцевины приводит к невозможности реализации полностью волоконных схем лазера. В связи с этим недавно была разработана конструкция специального Ybволоконного световода с легированной оболочкой [11]. Сопоставимость волноводных параметров сердцевины и оболочки световода с параметрами коммерчески доступных волоконных световодов позволило впервые реализовать полностью волоконную PM-схему Yb-лазера пикосекундной длительности [12], а так же полностью волоконную схему лазера, поставляющего импульсы, которые могут быть сжаты до фемтосекундной [13] длительности.…”