An Erbium-Doped Fiber Source with Near-Gaussian-Shaped Spectrum Based on Double-Stage Energy Matching and LPFGs

Abstract

An Erbium-doped fiber source with a near-Gaussian-shaped spectrum consisting of only a single peak, based on the double-stage energy matching and LPFGs, is proposed and demonstrated. A double-stage Erbium-doped fiber source system is built. The first-stage structure adopts the single-pass forward pumping method with a 15 m Erbium-doped fiber, while the second-stage structure adopts the backward-pumping method with a 26.5 m Erbium-doped fiber. The energy of the output spectrum is concentrated near the long wavelength (1560 nm) through the double-pump energy matching of the two stages. Long period fiber gratings (LPFGs) are used to filter the excess light near the short wavelength (1530 nm) in order to obtain a near-Gaussian-shaped spectrum consisting of only a single peak. The output power, pump conversion efficiency, line width, 3 dB bandwidth and mean wavelength of this near-Gaussian-shaped spectrum are tested and analyzed. When the pump powers of the first and second stages are 50 mW and 360 mW, respectively, the results show that a near-Gaussian-shaped spectrum with a power of 10.17 mW, spectral line width of 19.767 nm, and mean wavelength stability of −0.978 ppm/mW can be obtained. This research provides a method for the generation of a near-Gaussian-shaped spectrum with high output power and excellent mean wavelength stability, and it can produce multiple forms and energies of near-Gaussian-shaped spectra via this Erbium-doped fiber source.