Abstract
A distributed feedback (DFB) fiber laser with a ratio of the backward to forward output power of 1:100 was composed by a 45-mm-length asymmetrical phase-shifted fiber grating fabricated on the 50-mm erbium-doped photosensitive fiber. Forward output laser was amplified using a certain length of Nufern EDFL-980-Hp erbium-doped fiber to absorb the surplus pump power after the active phase-shifted fiber grating and get population inversion. By using OptiSystem software, the best fiber length of the EDFL to get the highest gain was simulated. In order to keep the amplified laser with the narrow line-width and low noise, a narrow-band light filter consisting of a fiber Bragg grating (FBG) with the same Bragg wavelength as the laser and an optical circulator was used to filter the amplified spontaneous emission (ASE) noise of the out-cavity erbium-doped fiber. The designed laser structure sufficiently utilized the pump power, and a DFB fiber laser with the 32.5-mW output power, 11.5-kHz line width, and −87-dB/Hz relative intensity noise (RIN) at 300 mW of 980 nm pump power was brought out.
Highlights
Distributed feedback fiber laser (DFB-FL) is a kind of laser consisting of a single phase shifted fiber grating directly writing in the rare earth doped fiber, depending on the narrow bandwidth, low noise, and stable single-mode operation, and it has the important application value as high sensitivity sensors in the acoustic, vibration signal detection technologies [1, 2]
Without the additional pump source, only a suitable length erbium-doped fiber connected on the fore-end of the distributed feedback (DFB)-FL was used to absorb the residual pump power and achieve population inversion, so Article type: Regular
In order to keep the amplified laser with the narrow line-width and low noise, a narrow-band light filter consisting of a fiber Bragg grating (FBG) with the same Bragg wavelength of the laser and an optical circulator was used to filter the amplified spontaneous emission (ASE) noise of the out-cavity erbium-doped fiber
Summary
Photonic Sensors the forward output laser would be amplified. In order to keep the amplified laser with the narrow line-width and low noise, a narrow-band light filter consisting of a fiber Bragg grating (FBG) with the same Bragg wavelength of the laser and an optical circulator was used to filter the amplified spontaneous emission (ASE) noise of the out-cavity erbium-doped fiber. A 30-mW DFB-FL with the narrow linewidth and low noise was employed. 2. Experiment and discussion the PS-FBG still reached 200 mW. Using the null method of measurement as shown, the DFB-FL’s linewidth and relative intensity noise (RIN) delay were 6.7 kHz and –102 dB/Hz, the laser signal-to-noise ratio was 65 dB, and the data are collected in Table 1 for the further discussion
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