Tunable Erbium-doped Fiber Laser Research Articles

1.6 µm tunable and switchable single-frequency erbium-doped fiber laser

We present a tunable and switchable single-frequency (SF) erbium-doped fiber laser (EDFL) operating at 1.6 µm. For the first time, a multichannel Sagnac filter, a “θ” sub cavity, and a saturable absorber (SA) have been combined to achieve SF operation of single- and dual-wavelength tunability as well as single-dual-triple-wavelength switching. The laser exhibited excellent stability, with no mode-hopping over the 60-minute observation period. Furthermore, linewidths measured utilizing the short-delay self-heterodyne interferometry method are less than 300 Hz. The investigated narrow linewidth SF EDFL has the potential to extend the applications in optical communications and provide a new idea for L-band tunable lasers.

Biological material spider silk by direct incorporation onto fiber ferrule for wavelength tunable Q-switched application

This study presents a novel structure saturable absorber (SSA) based on spider silk for wavelength tunable Q-switched erbium-doped fiber laser (EDFL) operation from S to L bands. The nonlinear optical absorption of spider silk was measured, showing a high modulation depth of 64.92%, a low saturation intensity of 0.03 MW cm−2, and a non-saturable loss of 24%. By adjusting the polarization controller, a wavelength tunable Q-switched EDFL was achieved, with a tuning range of 64 nm from 1522 nm to 1586 nm. The Q-switched pulses had a repetition rate varying from 20.62 kHz to 6.57 kHz and a pulse width ranging from 14.02 μs to 26.30 μs, corresponding to an output power from −11.31 dBm to −9.02 dBm at the maximum pump power of 151.40 mW. The proposed SSA using spider silk offers a low-cost, eco-friendly, and high-performance solution for wide wavelength tunable Q-switched EDFL applications in optical testing, fiber communication, optical fiber sensing, and ultrafast lasers.

Wavelength tunable ring cavity erbium-doped fibre laser based on tapered Fabry Perot filter fabricated by hydrofluoric acid corrosion for stretch sensing

In this study, the erbium-doped fiber laser with a ring cavity and a Fabry-Perot (F-P) filter was proposed and experimentally verified. In the design of the laser, hydrofluoric acid was employed for chemical etching to prepare the F-P cavity, and tapering was applied to the F-P cavity to enhance sensitivity. The experimentally prepared F-P filter was placed in the resonant cavity and served as a frequency-selective device for the fiber laser. At a laser threshold of 48 mW, we obtained a single-wavelength laser output at 1565.28 nm, with a 3 dB linewidth of 0.29 nm. To evaluate the stretching sensing performance of the EDFL system, we performed stretching of the F-P filter. The experimental results demonstrated that within a stretching length range of 0 to 3 mm, we could obtain a single-wavelength laser that could be tuned from 1559.57 to 1567.04 nm, corresponding to a tuning range of 7.47 nm. The laser showed a sensitivity of 2.73 nm/mm and a goodness of fit 0.999. Monitoring the stability of a single-wavelength laser within 30 min, the signal-to-noise ratio was greater than 27.212 dB, and the power fluctuation was less than 0.712 dB. Additionally, the polarization controller was adjusted to obtain two different dual-wavelength lasers with a power fluctuation of less than 0.71 dB.

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.

Wavelength tunable double-ring cavity erbium-doped random fiber laser based on a Mach–Zehnder interferometer

A wavelength-tunable double-ring cavity erbium-doped random fiber laser (RFL) based on a Mach–Zehnder interferometer (MZI) was proposed in this study. The MZI structure, which was based on two 2 × 2 optical fiber couplers, exhibits a comb-filtering effect. Rayleigh scattering (RS) was generated by a 10-km-long single-mode fiber (SMF) to provide randomly distributed feedback. A double-ring cavity structure based on forward and backward RS was built using two 2 × 2 fiber couplers. The threshold of the laser was 104 mW, and the slope efficiency of the total power output to the pump power was approximately 1.2%. When the pump power was 158 mW, a laser beam with a wavelength of 1555.3 nm was formed. By adjusting the polarization controller (PC), a single-wavelength switched RFL at 1547.9 nm and 1559.6 nm was obtained. The maximum peak power difference was less than 0.67 dB, the signal-to-noise ratio (SNR) was greater than 17.27 dB, and the peak power fluctuation was less than 0.92 dB during a scan time of 30 min at 25 °C. Regarding dual-wavelength switchable laser emission, two groups of different wavelengths with an SNR greater than 16.88 dB, power fluctuation less than 0.81 dB, and wavelength fluctuation less than 0.26 nm could be achieved under the same monitoring conditions. By further adjusting the PC, three- and four-wavelength RFLs were achieved, and the SNRs exceeded 16.31 dB and 14.64 dB, respectively. The proposed RFL has promising application prospects for distributed sensing systems and speckle imaging.

Switchable and tunable erbium-doped fiber laser with the embedded Lyot filter

Switchable and tunable erbium-doped fiber laser with the embedded Lyot filter

Cascaded C+L-band tunable erbium-doped fiber lasers for simultaneous generation of continuous wave and mode-locked pulses

Cascaded C+L-band tunable erbium-doped fiber lasers for simultaneous generation of continuous wave and mode-locked pulses

Electrically tunable mode-locked fiber laser using laser induced graphene assisted long-period fiber grating

We demonstrate an electrically tunable all-fiber mode-locked erbium-doped fiber laser using a long-period fiber grating (LPFG) assisted by laser induced graphene heaters (LIG-H). Wavelength tunability is achieved by the temperature-dependent transmission spectrum of the LPFG. The central wavelength can be continuously tuned from 1549.00 nm to 1563.63 nm with a spectral tuning range of 14.63 nm. The graphene on polyimide (PI) paper is fabricated using a 10.6 μm CO2 laser, which has a maximum operating temperature of around 500 °C. The proposed LPFG-based electrical tunability of mode-locked fiber laser provides a novel, repeatable, simple, and cost-effective laser tuning technique.

Tunable and switchable erbium-doped fiber laser based on the parallel filter of the FBGs embedded in Sagnac ring and the in-line MZI

A tunable and switchable erbium-doped fiber laser (EDFL) based on the parallel filter is proposed and experimentally verified. The parallel filter is composed of two branches. One branch is double fiber Bragg gratings (FBGs) embedded in Sagnac ring filter, which can realize the selection of two wavelengths; the other branch is an in-line Mach Zehnder interferometer (MZI) filter, which is composed of a 10 cm polarization-maintaining fiber (PMF) fused in the middle of single mode fibers (SMFs) with spheres at both ends, which can realize the selection of five wavelengths. When the parallel filter is inserted into the fiber laser cavity and the polarization controllers (PCs) are adjusted, the laser excitation from single-wavelength to quadruple-wavelength can be realized, including 7 different single-wavelength laser states, 16 different dual-wavelength laser states, 11 different triple-wavelength laser states and 2 different quadruple-wavelength laser states. In addition, the intervals of the dual-wavelength laser states are relatively regular, and the dual-wavelength laser intervals are obtained every ∼ 2 nm from 7 nm to 18 nm. And the optical signal-to-noise ratios (OSNRs) are more than 43 dB, and the highest OSNR is 60 dB. Finally, by changing the temperature applied to the FBG, tunability of dual-wavelength intervals can be achieved with a range of 1.1 nm. Due to the variety of lasing laser states of the fiber laser, easy switching, and regular intervals between the dual-wavelength laser states, the fiber laser proposed can be better applied to wavelength division multiplexing (WDM)system.

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.

A kind of multiwavelength erbium-doped fiber laser based on Lyot filter

A multiwavelength tunable ring-cavity erbium-doped fiber laser (EDFL) based on a Lyot filter was presented. For the proposed Lyot filter, a comb filter consisting of an EDF-polarization-maintaining fiber (EDF-PMF), a polarization controller (PC), and a circulator with four ports was used to suppress the mode competition. The light transmission direction was guaranteed by the circulator. For the proposed fiber laser, tunable single, dual, triple, quadruple, quintuple, sextuple, and septuple wavelengths were realized. A single-wavelength laser output with an optical signal-to-noise ratio (SNR) of up to 30.56 dB was realized, and a tuning range of 1590.54 nm to 1599.54 nm was achieved by tuning the PC. The stability of the single, dual, triple, and quadruple-wavelength center power fluctuations was less than 0.05 dB, 0.98 dB, 5.07 dB, and 7.71 dB respectively. When the laser was operated in the multiwavelength condition, the SNR was more than 20.97 dB. The proposed erbium-doped fiber laser is suitable for fiber-sensing system applications.

Switchable and tunable erbium-doped fiber laser based on the in-line MZI filter of the spheres and polarization-maintaining fiber

Switchable and tunable erbium-doped fiber laser based on the in-line MZI filter of the spheres and polarization-maintaining fiber

Tunable multiwavelength Erbium-doped fiber laser based on in-fiber Fabry-Perot interferometer fiber Bragg gratings in linear and ring cavity configurations

Multiwavelength Erbium-doped fiber laser (MWEDFL) in the ring and linear cavities operating at 1.5-μm wavelength region was demonstrated. The multiwavelength fiber laser comprises a 3-m Erbium-doped fiber as an active gain medium, an in-fiber Fabry-Perot interferometer Fiber Bragg Gratings (FPI FBG) as a filter, and a 10-km dispersion compensating fiber (DCF) as a nonlinear gain medium. A comparison investigation was conducted. The MWEDFL in the linear cavity generates 12 stable lasing lines, with an optical signal-to-noise ratio (OSNR) of 45 dB. In the case of MWEDFL operated in a ring cavity, 8 stable lasing lines were generated, with an OSNR of 47 dB. The free spectral range (FSR) of 0.08 nm was measured for the FPI FBG in both linear and ring cavities MWEDFL spectrum. Besides, the stability measurement was conducted for 150 min for both MWEDFL cavities. Both lasers had a peak power fluctuation of less than 1.0 dB and negligible wavelength drifts below 0.1 nm. Furthermore, the wavelength tunability of MWEDFL in both configurations was performed by heating the FPI FBG from 28 °C to 100 °C. At the temperature of 100 °C, the MWEDFL shows a wavelength shift of 1.0 nm, and this can be further increased by heating the FPI FBG to its highest temperature limit. This MWEDFL employs in-fiber FPI FBG offers a compact, highly tunable, and simple design applicable for optical communications and optical sensing applications.

Tunable and interval-adjustable multiwavelength Erbium-doped fiber laser based on a compound filter

We propose and experimentally demonstrate a multiwavelength erbium-doped fiber laser (EDFL) based on a compound filter. The compound filter is composed of polarization controllers (PCs), polarizers and a piece of home-made polarization-maintaining photonic crystal fiber (PM-PCF). Due to the high birefringence and few-mode properties of the PM-PCF, Lyot filter and multimode interference filter can be realized simultaneously in the compact structure. Hence, the EDFL can achieve flexible lasing output. By adjusting PCs, the lasing can obtain single-, dual-, triple- and quad-wavelength output, respectively. The tuning range of single-wavelength lasing output can exceed 20 nm with side-mode suppression ratio (SMSR) above 40 dB. For dual-wavelength lasing output, the tuning range with fixed interval can reach 16 nm. Besides, the wavelength interval can be adjusted from 2.5 nm to 17.4 nm. The great interval adjustability is also observed in triple-wavelength output. The wavelength interval can be adjusted from 8.2 nm to 14.7 nm. Compact structure, flexible lasing output, and good stability make our proposed EDFL more convenient and practical to the applications such as sensing and wavelength division multiplexing.

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.

Tunable and wavelength interval precisely controlled erbium-doped fiber laser by employing the fused taper technology

A tunable multi-wavelength erbium-doped fiber laser with precise wavelength interval control is reported theoretically and experimentally in this paper. It is made up of a Mach–Zehnder interferometer (MZI) filter and a Sagnac filter and supplemented by the four-wave-mixing effect. Compared with other filters, the proposed MZI filter based on the fused taper technology can change the wavelength interval more flexibly. The experiment result shows that wavelength tuning can be achieved, and the tuning range can reach ∼15 nm. Moreover, the variation in the number of wavelengths is also realized. The maximum side-mode suppression ratio can reach 39 dB.

Switchable and Tunable Erbium-Doped Fiber Laser Based on In-Line Mzi Filter of the Spheres And Polarization Maintaining Fiber

Switchable and Tunable Erbium-Doped Fiber Laser Based on In-Line Mzi Filter of the Spheres And Polarization Maintaining Fiber

Tunable filter based on two concatenated symmetrical long period fiber gratings as Mach-Zehnder interferometer and its fiber lasing application

This work presents a highly stable switchable and tunable erbium-doped fiber laser based on a Mach-Zehnder interferometer (MZI) made with two symmetrical LPFGs separated by an SMF segment of 5 cm in length. The core and the cladding of the SMF central segment act like the MZI arms, whereas the LPFG1-SMF and SMF-LPFG2 splices act as optical couplers. The emission is switchable from one single emission at 1563.6 nm, a side mode suppression ratio (SMSR) of ∼55 dB, and linewidth of 0.15 nm, to a dual emission located at 1563.98 and 1573.89 nm, reaching a high SMSRs of 56 dB, and linewidths ∼0.10 nm. Moreover, the laser emission can be tuned from 1569 to 1572 nm applying torsion to the MZI from 0° to 330° obtaining a nearly linear sensitivity of 9.2 pm/° with low hysteresis. Additionally, the laser operation stability was tested over 60 min, obtaining the power and wavelength fluctuations lower than 0.086 dB and 0.028 nm respectively. To the best of our knowledge, this is the first time that symmetric LPFGs have been used as a torsion sensitive WSF. For its high wavelength stability and SMSR, the MZI can be a low-cost alternative WSF while the switchable and tunable laser can be useful as an optical source for spectroscopy and communications applications.

Switchable and tunable linear cavity erbium-doped fiber laser based on FBGs embedded in Sagnac rings

A switchable and tunable erbium-doped fiber laser with a linear cavity based on fiber Bragg gratings embedded in Sagnac rings is proposed and experimentally verified. Due to the stress birefringence effect and the polarized hole burning effect, which are introduced into the single-mode fiber in the polarization controllers (PCs) by the PCs, the designed laser can achieve seven kinds of laser-states output including three kinds of single-wavelength laser states, three kinds of dual-wavelength laser states and one kind of triple-wavelength laser state. The optical signal-to-noise ratios of the output wavelengths are all higher than 52 dB, and the wavelength shifts are all less than 0.04 nm. Furthermore, the temperature tuning of the wavelength range is also researched, which is about 1.2 nm. Due to advantages, such as low cost, simple structure, easy switching and multiple laser states, the designed laser has great application potential in laser radar, optical fiber sensing and so on.