Switchable Multi-wavelength Erbium-doped Fiber Laser Research Articles

Tunable and switchable multiwavelength fiber laser incorporating tapered few-mode fiber Bragg gratings

A tunable and switchable multiwavelength Erbium-doped fiber laser (MWFL) is proposed and demonstrated based on tapered few-mode fiber Bragg gratings (TFMFBG). Optical modes inside TFMFBG have extensive evanescent tails that are sensitive to changes in the external medium. The MWFL can be tuned in the 1.5 µm wavelength region when temperature and refractive index variations are applied to the TFMFBG. The temperature and refractive index sensitivities range from 11.5 pm/⁰C to 14.6 pm/⁰C and 3.10 nm/RIU to 3.93 nm/RIU, respectively. Additionally, due to the polarization dependency of TFMFBG, single-, dual-, and triple-wavelength lasing lines can be switched within the MWFL cavity. The stable triple-wavelength lasing was generated at peak wavelengths of 1533.04 nm, 1532.35 nm, and 1531.71 nm for λ1, λ2, and λ3, respectively. The developed triple-wavelength laser corresponded to a specific guided mode inside the few-mode FBG, including fundamental LP01 mode, higher-order LP11 mode, and mode coupling between LP01 and LP11 (LP01-LP11).

A C-band widely tunable and switchable erbium-doped fiber laser based on a Sagnac-like loop embedded in Lyot filter

In this paper, a new type of widely tunable and switchable multi-wavelength erbium-doped fiber laser based on a Sagnac-like loop embedded in Lyot filter is proposed. The nonlinear polarization rotation effect is obtained by adjusting two polarization controllers (PCs). The polarization-dependent isolator and the Sagnac-like loop are used as the basic structure to realize the wide tuning and wavelength switching in C-band. Compared with the traditional Lyot filter, the Sagnac-like loop is used to replace the segment of polarization-maintaining fiber, and a more uniform comb spectrum can be obtained by this filter. The tunable and switchable wavelengths can be achieved by adjusting the PCs based on the nonlinear effect of the loop. The laser can emit single-, dual-, triple-, quad- and quintuple-wavelengths. The optical signal-to-noise ratios all exceed 43 dB. It can also be adjusted to partial wavelength intervals for quad-wavelength and quintuple-wavelength. The tuning range can reach the full range of the C-band, and the laser efficiency can reach the practical application standard. It can be applied to some precision instruments and equipment.

Tunable and Switchable Multi-Wavelength Erbium-Doped Fiber Laser Based on Composite Structure Filter

A multi-wavelength erbium-doped fiber laser (MW-EDFL) with wide tuning range, switching and adjustable wavelength interval is designed and tested, which is based on a composite filter. The filter consists of a tapered microfiber coupler loop (TMCL) with a nested single mode fiber (SMF)-two mode fiber (TMF)-SMF (STS) structure, which has a comb spectrum with obvious envelope and uniform fluctuation. Our experimental and theoretical results show that the laser can output thirteen wavelengths, when the angles of two polarization controllers (PCs) in the TMCL are accurately set. Moreover, by adjusting the PCs, the tuning range of single- to sextuple-wavelength can reach about 40 nm. Six non-adjacent multi-wavelength outputs can be observed in some specific polarization states. The maximum side-mode suppression ratio (SMSR) of the output laser is 40.6 dB. Compared with other multi-wavelength EDFL, the output characteristics of the laser, such as the adjustability and flexibility of wavelength spacing and the switch-ability of wavelength number, have been improved.

Widely tunable and switchable multiwavelength erbium-doped fiber laser based on a single ring cavity

In this paper, we propose and demonstrate through numerical simulations a novel, to the best of our knowledge, widely tunable and switchable multiwavelength erbium-doped fiber laser (EDFL) operating in the 1524–1650 nm wavelength range covering the C-, L-, and U-bands. The EDFL is based on a single ring cavity and a single forward pump source operating at 980 nm wavelength. The length of the erbium-doped fiber and pumping configuration is optimized, enabling a wide tuning of 126 nm with an average lasing power of 15 dBm. Switchable multiple wavelengths are generated from the EDFL through an intracavity tunable optical filter (TOF) and a specially designed out-of-cavity comb filter (CF). Forty-nine wavelengths having average optical power and linewidth of around −10 dBm and 0.01 nm, respectively, are obtained at the output of the CF. Moreover, the free spectral range among the multiple wavelengths is adjusted easily by simply varying the frequency of sinusoidal radio frequency signal used to modulate the lasing signal obtained by tuning the intracavity TOF at a particular wavelength with the help of a dual-drive Mach–Zehnder modulator. The proposed EDFL is low cost, efficient, and highly stable with an average output power of around 15 dBm for 10% output coupling ratio over a 126 nm wide tuning range covering C-, L- and U-bands.

Low threshold multi-wavelength erbium-doped fiber ring laser with NOLM and Lyot filter

In this paper, the performance of a switchable multi-wavelength erbium-doped fiber laser (MWEDFL) incorporating Lyot filter and nonlinear optical loop mirror (NOLM) is described. The NOLM consisting of a polarization controller (PC2) and a single-mode fiber is effective to suppress the mode competition caused by the homogeneous broaden line in the erbium-doped fiber amplifier (EDFA). The comb filter is developed by using PC1 and polarization-maintained fiber (PMF). The wavelength interval can be switched among 0.08 nm, 0.34 nm, and 0.89 nm using different lengths of PMF via careful adjusting of the PCs. When the pump power is 45mW, the laser can emit 12 stable lasing lines within the 3 dB bandwidth, and the side mode suppression ratio (SMSR) is greater than 25 dB. The spectral power and wavelength fluctuations of 1.9 dB and 0.16 nm, respectively. Experimental results reveal that the demonstrated laser has good stability and low threshold power.

A switchable multi-wavelength EDFL using cascaded Sagnac fiber loops with mode differential delay line

We propose and experimentally demonstrate a switchable multi-wavelength Erbium-doped fiber laser that employs cascaded weakly-coupled few-mode fiber (FMF) Sagnac fiber loops with mode differential delay line. A comb filter of multiple specific wavelengths is performed by incorporating a weakly-coupled FMF in cascaded Sagnac fiber loops. The incorporation of the weakly-coupled FMF is realized with all-fiber mode multiplexer/demultiplexer (MUX/DEMUX), which can simultaneously generate transversal LP01 and LP11 modes. The comb filter characteristics of cascaded Sagnac fiber loops are simulated and analyzed by Jones matrix. By adjusting the polarization controllers (PCs), the fiber laser can operate in single-, dual-, and triple-wavelength laser states around C band. The side mode suppression ratio is larger than 30.0 dB. Moreover, the laser output stabilities for single-, dual-, and triple-wavelength lasing are investigated in a range of over 30 min at room temperature. Experimental results indicate that this work has potential applications in WDM systems, sensing, and instrument testing.

Switchable Multi-wavelength Erbium-doped Fiber Laser Based on a Microfiber Sagnac Loop

Switchable Multi-wavelength Erbium-doped Fiber Laser Based on a Microfiber Sagnac Loop

Wavelength Switchable Multi-Wavelength Erbium-Doped Fiber Laser Based on Polarization-Dependent Loss Modulation

We propose and demonstrate a novel and simple wavelength switchable multi-wavelength erbium-doped fiber (EDF) laser based on polarization-dependent loss (PDL) modulation with cascaded fiber Bragg gratings (FBGs) as the wavelength comb filter. PDL is generated and controlled by different polarization angles between the polarization state of each lasing line and the optical fiber polarizer in the laser cavity. The PDL modulation balances the difference between the total loss and the wavelength-dependent lasing gain. The relations among gain, loss, and laser output power under different PDL conditions are numerically analyzed on the basis of a simplified Giles model in an EDF laser system. Results show that multi-wavelength lasing lines can be built up by properly tuning the PDLs in different wavelengths. The amount of lasing lines can be switched by changing the PDL intensity in a certain wavelength. In an experiment, the PDL in that certain wavelength is modulated by utilizing four polarization controllable elements, each of which includes an FBG and a corresponding polarization controller (PC). One PC is used to control the polarization state of the reflected lasing line on the center wavelength of the FBG. A four-wavelength individually switchable EDF laser system is demonstrated by utilizing this wavelength switchable method, in which the switching operation for the single-, dual-, triple-, and four-wavelength laser output is verified. The experimental results are consistent with the theoretical results. All wavelength switching operations are conveniently controlled by merely adjusting the PCs. This simple structure and flexible wavelength switchable operations show that this multi-wavelength EDF laser has great potential in practical applications.

Switchable multi-wavelength erbium-doped fiber laser based on core-offset structure and four-wave-mixing effect

Abstract A switchable multi-wavelength erbium-doped fiber laser (EDFL) based on the two-mode fiber (TMF) with core-offset structures and the four-wave-mixing effect (FWM) is experimentally demonstrated in this paper. The proposed filter is constructed by splicing a section of TMF with two segments of single-mode fiber (SMF) and the insertion loss is ~0.4 dB, which is smaller than the most of offset structures. The filter is based on the interference of the LP01 mode and the LP11 mode, which are excited by the core-offset structure. Due to the characteristics of the filter spectra and wavelength competition, the output wavelengths can be single-, dual-, and triple-wavelength by adjusting polarization controller (PC). In order to mitigate the intense gain competition, the FWM is introduced by using highly nonlinear fiber (HNLF) and SMF, respectively. Benefiting from the intensity-dependent gain caused by FWM, the number of output lasers increases and outputs are more flexible, which can be quadruple-, quintuple-, septuple- and decuple-wavelength by adjusting PC. The flatness of the wavelengths is also studied.

Switchable Multi-Wavelength Erbium-Doped Fiber Laser With Adjustable Wavelength Interval

A switchable multi-wavelength erbium-doped fiber laser based on parallel dual Lyot filters is experimentally demonstrated in this paper. A new type of parallel-structure fiber filter is designed and its spectrum is simulated. The structure is simple. The spectra of the filter changes when adjusting the polarization states of the polarization controllers. Due to the characteristics of the filter spectra and wavelength competition, the output wavelengths can be single wavelength, dual wavelengths, and triple wavelengths. When the output is single wavelength, the lasing wavelength is tunable with a tuning range of ∼13 nm. The wavelength interval of dual wavelengths can be adjusted from 3.03 to 17.15 nm, which is a relatively wide range. The interval of three wavelengths also changes to some extent. Moreover, the optical signal-to-noise ratios of the output wavelengths can be up to 47 dB.

Switchable multi-wavelength random distributed feedback fiber laser

A novel switchable multi-wavelength erbium-doped fiber laser based on random distributed feedback is demonstrated in this paper. Based on loop mirror to form a half-opened laser cavity, typical random laser radiation is achieved with an obvious threshold behavior as a function of pump power. Switchable multi-wavelength lasing operation is also achieved by changing attenuation value through the variable optical attenuator. Due to the efficient gain from the pumped erbium-doped fiber, a low threshold power of 22 mW is achieved, which is much lower in magnitude than that of previously reported conventional random fiber lasers.

Switchable multi-wavelength erbium-doped fiber laser based on a four-mode FBG

We propose a switchable multi-wavelength erbium-doped fiber laser based on a four-mode fiber Bragg grating (FBG). The four-mode FBG is fabricated in a hydrogen pre-loaded fiber by the phase mask method, which can support four linearly polarized modes around 1550 nm. The five operation wavelengths are at 1547.5, 1546.8, 1546.0, 1545.1, and 1544.2 nm, respectively. Through adjusting the polarization state and the lateral offset coupling in cavity, the laser can be switched into the operation state of single, dual, or triple wavelengths. The proposed laser has the advantages of simple configuration, stable operation, and easy adjustment.

Switchable multi-wavelength and tunable wavelength spacing erbium-doped fiber laser based on a phase-shifted fiber Bragg grating combined with a Mach-Zehnder interferometer

A switchable multi-wavelength fiber laser with tunable wavelength spacing is proposed. It is based on a structure filter composed of a phase-shifted fiber Bragg grating (PSFBG) and a Mach-Zehnder interferometer (MZI), and the MZI is fabricated by splicing a section of polarization-maintaining fiber with two segments of multi-mode fibers. By adjusting the variable optical attenuator in the cavity and slightly changing the temperature, stable single-, dual-, triple- and quadruple-wavelength emissions can be obtained. The minimum wavelength spacing of adjacent peaks is 0.176 nm, and the maximum is 17.86 nm. The laser line emissions can be switched from 1527.684 nm to 1550.224 nm with optical signal to noise ratio of more than 50 dB. The maximum wavelength fluctuation of the fiber laser is less than 0.025 nm over 50 min. When the strain applied to the filter is changed, the tunable wavelength spacing can be achieved. The wavelength spacing of dual-wavelength laser can be continuously tuned from 21.82 nm to 22.69 nm by applying strain of 0–258 με to the filter.

C-band switchable multi-wavelength erbium-doped fiber laser based on Mach–Zehnder interferometer employing seven-core fiber

Abstract In this study, we propose and test a linear cavity erbium-doped fiber laser that incorporates a seven-core-based Mach–Zehnder interferometer (MZI). A 3.6-m-long erbium-doped fiber was selected as the gain medium. The all-fiber MZI was composed of two 105/125 μm multimode fibers and one seven-core fiber as the wavelength comb filter. A lasing threshold of 73 mW was used in the experiment, and a switchable laser with stable single and dual wavelengths was implemented by adjusting the polarization controller. In the experiment, five different single-wavelength lasers could be realized with power fluctuations lower than 0.98 dB within 10 min of scan time. In addition, five different dual-wavelength lasers could be obtained with a power shift lower than 1.09 dB at room temperature.

Erbium-doped fiber ring laser with wavelength selective filter based on non-linear photonic crystal fiber Mach–Zehnder interferometer

A high output power, stable wavelength spacing and switchable multi-wavelength erbium-doped fiber laser has been demonstrated experimentally using a combination of non-linear photonic crystal fiber Mach–Zehnder (MZI) interferometer with polarization dependent loss effect. This MZI functions together with a polarization controller (PC) as a wave selecting filter (WSF). Adjusting the PC within the WSF part gives rise to three emissions as single, dual and triple wavelengths. Multi-wavelength laser with maximum spacing of 1.6 nm was achieved by controlling the polarization state in a ring cavity. Such stable wavelength spacing aroused interest in wavelength-division-multiplexer systems. Output power around −3 dB at 1550 nm wavelength, with small power fluctuation for each line, was recorded at room temperature. The measured 3-dB laser line-width was 0.03 nm, with a high side-mode suppression ratio of 48 dB.

A nonlinear optical loop mirror-based linear cavity switchable multi-wavelength erbium-doped fiber laser

A nonlinear optical loop mirror (NOLM)-based linear cavity switchable multi-wavelength erbium-doped fiber (EDF) laser is proposed and experimentally demonstrated. Due to the characteristics of the intensity-dependent transmissivity, the NOLM can effectively mitigate the mode competition of the homogenous broadening gain medium, so that the multi-wavelength lasing can be achieved at room temperature. By adjusting the states of the polarization controllers (PCs), the number of the lasing wavelengths in the proposed laser can be adjusted flexibly from 11 to 13 with a wavelength spacing of 0.4 nm around the wavelength of 1 530 nm.

Switchable multi-wavelength fiber laser based on modal interference

A comb fiber filter based on modal interference is proposed and demonstrated in this paper. Here two cascaded up-tapers are used to excite the cladding mode, and a core-offset jointing point is used to act as an interference component. Experimental results show that this kind of structure possesses a comb filter property in a range of the C-band. The measured extinction ratio is better than 12 dB with an insertion loss of about 11 dB. A switchable multi-wavelength erbium-doped fiber laser based on this novel comb filter is demonstrated. By adjusting the polarization controller, the output laser can be switched among single-, dual-, and three-wavelengths with a side mode suppression ratio of better than 45 dB.

Switchable multi-wavelength erbium-doped photonic crystal fiber laser based on nonlinear polarization rotation

A multi-wavelength erbium-doped photonic crystal fiber (ED-PCF) ring laser based on nonlinear polarization rotation was demonstrated experimentally. To the best of our knowledge, this study is the first to use a polarization-dependent isolator with an ED-PCF to form an equivalent fiber filter. The intensity-dependent inhomogeneous loss induced by nonlinear polarization rotation was applied to reduce the mode competition caused by ED-PCF. A detailed theoretical analysis using the Jones matrix method to calculate the transfer function of the laser was presented. The theoretical data, which were confirmed by the experimental results, showed that a multi-wavelength with a spacing of approximately 2.26nm was achieved by controlling the polarization controller. The proposed fiber laser with a signal-to-noise ratio higher than 40dB achieved a low threshold power of 30mW. Therefore, stable multi-wavelength outputs with a power fluctuation of less than 2dB were generated at room temperature.

A dual-reflected-structure switchable multi-wavelength erbium-doped fiber laser using the multi-mode fiber as the wavelength selector

A simple and effective dual-reflected-structure switchable multi-wavelength polarization-maintaining erbium-doped fiber laser is proposed and demonstrated. Using the structure of single-mode fiber (SMF)-multi-mode fiber (MMF)-SMF as the wavelength selective filter and reflector simultaneously the polarization-maintaining erbium-doped fiber as the gain medium and an optical circulator as the all-reflecting mirror, the laser realizes stable single-wavelength, dual-wavelength and triple-wavelength oscillations based on polarization hole burning of a multi-mode fiber by means of adjusting the polarization controller. The 3 dB bandwidth is about 0.01 nm. The side-mode suppression ratios (SMSRs) are over 50 dB. The power fluctuation and wavelength shifts are measured to be less than 1.5 dB and 0.01 nm over an hour at room temperature.

A Switchable Multi-wavelength Erbium-Doped Photonic Crystal Fiber Laser with Linear Cavity Configuration

A switchable multi-wavelength erbium-doped photonic crystal fiber laser with a linear cavity configuration based on a Sagnac loop mirror is proposed and demonstrated experimentally. The laser is based on saturated spectral hole burning and the polarization hole burning effects can be switched among single-wavelength, dual-wavelength, triple-wavelength and quadruple-wavelength outputs at room temperature. The wavelength period of the output spectrum is easily varied by using polarization maintaining fibers of different lengths. The proposed fiber laser has a signal-to-noise ratio of higher than 30 dB and achieves a low threshold power of 37mW. The power fluctuations of the lasing lines are less than 0.54 dB, 1.7 dB and 2.9 dB when the laser operates at single-wavelength, dual-wavelength and triple-wavelength for one hour.