Abstract
We demonstrate efficient pulse-energy extraction from a partly quenched erbium-doped aluminosilicate fiber amplifier. This has a high erbium concentration that allows for short devices with reduced nonlinear distortions but also results in partial quenching and thus significant unsaturable absorption, even though the fiber is still able to amplify. Although the quenching degrades the average-power efficiency, the pulse energy remains high, and our results point to an increasingly promising outcome for short pulses. Furthermore, unlike unquenched fibers, the conversion efficiency improves at low repetition rates, which we attribute to smaller relative energy loss to quenched ions at higher pulse energy. A short (2.6 m) cladding-pumped partly quenched Er-doped fiber with 95-dB/m 1530-nm peak absorption and saturation energy estimated to 85 µJ reached 0.8 mJ of output energy when seeded by 0.2-µs, 23-µJ pulses. Thus, according to our results, pulses can be amplified to high energy in short highly Er-doped fibers designed to reduce nonlinear distortions at the expense of average-power efficiency.
Highlights
Erbium-doped fiber amplifiers (EDFAs) and lasers enable versatile and compact optical sources in the wavelength range of ∼1.5–1.6 μm (e.g., [1,2,3,4,5,6,7,8,9,10,11]), and can readily be cladding-pumped with over 100 W of power from 980-nm diode lasers at low cost
Compared to the prototype from SPI Lasers, this was better suited to the low input power to the 2nd EDFA that resulted with path a, which could be as low as 10 μW
Our results demonstrate that short pulses can efficiently extract high energy from a partly-quenched high-concentration erbium-doped fiber amplifier, even though the fiber exhibits significant unsaturable absorption in the CW regime
Summary
Erbium-doped fiber amplifiers (EDFAs) and lasers enable versatile and compact optical sources in the wavelength range of ∼1.5–1.6 μm (e.g., [1,2,3,4,5,6,7,8,9,10,11]), and can readily be cladding-pumped with over 100 W of power from 980-nm diode lasers at low cost. The quenching process is often assumed to be instantaneous, but this may exaggerate the impact of the quenching on such pulses In this regime, a finite quenching time may allow for high-energy pulse amplification at higher quenching-levels than normally considered. We present an experimentally based investigation of the impact of quenching on amplification of high-energy pulses of 6 ns - 20 μs duration in a cladding-pumped Er-doped fiber with a high Er3+-concentration, partly-quenched with 16.3% unsaturable absorption at 1536 nm. Compared to our previous conference publication [44], we investigate shorter pulses with an improved setup
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