Abstract
A tunable spacing dual-wavelength Q-switched fiber laser is experimentally demonstrated based on a fiber Bragg grating tunable device incorporated in an erbium-doped fiber laser (EDFL). The system utilizes two identical fiber Bragg gratings (FBGs) at 1547.1 nm origin to enable two laser lines operation. The wavelength separations between two laser lines are controlled by fixing one of the FBGs while applying mechanical stretch and compression to the other one, using a fiber Bragg grating tunable device. The seven steps of wavelength spacing could be tuned from 0.3344 to 0.0469 nm spacing. Pulse characteristics for both close and wide spacing of dual-wavelength Q-switched fiber laser are successfully being recorded. The findings demonstrate the latest idea of dual-wavelength fiber laser based on FBG tunable device, which offers a wide range of future applications.
Highlights
We focus on prior work utilizing fiber Bragg grating as a wavelength filter, which may be classified into two types, one involving just one fiber Bragg gratings (FBGs) and the other including two FBGs for dual-wavelength output design
The FBG deformation lead to a displacement of the Bragg wavelength, which allowed for tuning of the wavelength of the generated laser line [41]
The optical signal-to-noise ratio losses to both FBGs used in the design
Summary
Dual-wavelength fiber lasers, which are versatile light sources capable of providing more than single discrete laser emission lines, have sparked considerable interest in a wide range of applications, including remote sensing instruments [1,2] and fiber-based sensors [3,4,5,6], optical communication systems, microwave photonics [7,8,9,10], millimeterwave [11] and terahertz waves [12,13], spectroscopy [14] and biomedical research [15]. Many approaches for generating dual-wavelength lasing that implementing various techniques have been proposed, including utilization of comb filters with specialty fiber [16,17,18], phase modulator [19,20], nonlinear optical effects [21,22] and hybrid-gain schemes [23]. Having these techniques in a passively Q-switched fiber laser mechanism will generate dual laser lines with pulsed output. We propose a new simple tunable dual-wavelength Q-switched fiber laser by using carbon nanotubes (CNT) as a saturable absorber (SA). The homogenous CNT/PVA thin film was peeled off from the petri dish and was ready to be used as the saturable absorber
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