Tunable multiwavelength erbium-doped fiber laser based on nonlinear optical loop mirror and birefringence fiber filter

Abstract

four-wave mixing [1,2], polarization hole burning [3,4], frequency shift feedback [5], intensity-dependent loss (IDL) [6][7][8][9], phase modulation [10], stimulated Brillouin scattering [11], etc. In practical applications, it highly demands tunable MWEDFL which allows that both the number and the wavelength of lasing lines can be tunable for a better convenience.In order to build tunable MWEDFL, there are two primary methods. The first type is based on the IDL effect. IDL effect is usually induced by nonlinear optical loop mirror (NOLM) or nonlinear polarization rotation (NPR), in which input signal with higher power obtains higher loss than the one with lower power when it feedbacks to the laser cavity. This feature can be used as an intensity equalizer to suppress the mode competition and obtain the stable multiwavelength oscillation [6-9]. As the multiwavelength lasing oscillation is a balance between IDL and mode competition, the change in IDL breaks the original balance state, resulting in the change in number and wavelength of lasing lines. Through IDL modulation, the adjustments for number of lasing lines within dozens amount and wavelength range shift within 30 nm have been experimentally demonstrated [6]. However, because the comb filter is not tunable, the channel wavelength is fixed. In wavelength tuning, the lasing lines just jump among channels defined by the comb filter, meaning the scanning resolution is determined by the channel spacing [6,8].The other method is actively tuning the transmission spectrum of a comb filter and consequently tuning multiwavelength lasing output characteristics, such as lasing lines number and wavelength. There are also two types of tunable comb filters that have been studied for this purpose. The first type of filter is based on the tunable periodic comb filter, including birefringence fiber filter (BFF) [9], MachZehender interferometer (MZI) [10,12], superimposed Abstract A tunable multiwavelength erbium-doped fiber laser (MWEDFL) based on nonlinear optical loop mirror (NOLM) and tunable birefringence fiber filter (BFF) is proposed and demonstrated. By combination of intensitydependent loss modulation induced by NOLM and pump power adjustment, the proposed laser can achieve independent control over the number of lasing lines, without affecting other important characteristics such as channel spacing and peak location. In addition, the laser allows wavelength tuning with both the peak location and the spectral range of lasing lines controllable. Specifically, the peak location of lasing lines can be controlled to scan the whole spectral range between adjacent channels of comb filter by adjusting the BFF. Moreover, the spectral range of lasing lines can be controlled by adjusting NOLM. This tunable MWEDFL may be useful for fiber-optic communication and fiber-optic sensing.

Twenty two flattened channels L band multi-wavelength erbium doped fiber laser with composite ring cavity

“…There are two designs deemed reliable in producing a comb of multiwavelength fiber laser namely the linear cavity and ring cavity [21][22][23][24]. To reliable the multiwavelength operation, many effort and techniques have been done such fiber Bragg grating based Fabry perot filter [25], nonlinear effect, four-wave mixing (FWM) and Brillouin [5,26,27], birefringence fiber filter [28], Sagnac loop mirror or nonlinear optical loop mirror (NOLM) [29,30], lyot filter [31] and so forth.…”

Effect of Rayleigh backscattering on the multiwavelength random fiber laser bandwidth

“…The technique of nonlinear polarization rotation (NPR) effect through the intensity-dependent loss (IDL) mechanism is necessary to suppress this mode competition [13,14]. The NPR effect is formed from the combination of a polarization controller (PC), highly nonlinear fiber (HNLF), and polarizer which balances the oscillation and produces a stable multiwavelength output [15].…”

Wavelength switchable and stable single-longitudinal-mode erbium-doped fiber laser based on Mach–Zehnder interferometer and tunable filter

“…[1][2][3][4] As one of the current research subjects, the erbium-doped fiber laser (EDFL) can exit C-band lasers, and are used in many applications. [5][6] In recent years, some techniques have been reported to realize wavelength switchable and stable EDFL, such as the Mach-Zehnder interferometer (MZI) based on photonic crystal fiber, [7][8] Lyot-Sagnac filter, [9] nonlinear amplifying loop mirror, [10] hollowcore Bragg fiber, [11] tapered fiber filter, [12] few-mode polarization maintaining fiber loop mirror, [13] no-core fiber, [14] dual-ring structure, [15] closed-loop piezoelectric ceramics, [16] chirped fiber grating, [17] birefringence fiber filter, [18] tunable filter, [19] and twin-core fiber. [20] As mentioned above, in the wavelength switchable EDFL, the filter was an important component and it influences laser tuning ability.…”