Erbium-doped Fiber Laser Cavity Research Articles

Evaluation of an Erbium-Doped Fiber Ring Laser as an Edge Filtering Device for Fiber Bragg Grating Sensor Interrogation

An easy-to-implement and cost-effective Fiber Bragg Grating (FBG) sensor interrogation technique based on a ring Erbium-Doped Fiber Laser (EDFL) topology is proposed and experimentally assessed. The FBG sensor is part of the EDFL cavity and must have a central wavelength located within the linear region of the EDF’s amplified spontaneous emission (ASE) spectrum, which occurs at between 1530 and 1540 nm. In this manner, the wavelength-encoded response of the FBG under strain is converted to a linear variation in the laser output power, removing the need for spectrum analysis as well as any limitations from the use of external edge-filtering components. In addition, the laser linewidth is significantly reduced with respect to the FBG bandwidth, thus improving the resolution of the system, whereas its sensitivity can be controlled through pumping power. The performance of the system has been characterized by modeling and experiments for EDFs with different lengths, doping concentrations, and pumping power levels. The influence of mode-hopping in the laser cavity on the resolution and accuracy of the system has also been investigated.

Fe-MOF as a novel saturable-absorber for pulse operation in erbium-doped fiber lasers

This study demonstrated the utilization of an iron metal–organic framework (Fe-MOF) thin film to act as a saturable absorber in a passively Q-switched erbium-doped fiber laser cavity. The Fe-MOF thin film was prepared using the conventional solution method technique and was characterized using XRD, SEM, EDX, and Raman. The integration of Fe-MOF thin film into fiber ferrule yields a stable self-starting Q-switching operation at a pump power of 55.4 mW. Besides at a maximum pump power of 531 mW, emission at 1561.8 nm, minimum pulse duration of 3.9 µs, maximum repetition rate of 91.7 kHz, and a maximum average output power of 10.8 mW was achieved. The measured results further reveal a maximum 53 dB single-to-noise ratio (SNR), signifying good pulse stability. Moreover, we examined a Fe-MOF-SA damage threshold and long-term stability. The optimum stability, excellent threshold, and shorter pulse width highlight the potential of Fe-MOF as a promising saturable absorber (SA) in a passively Q-switched fiber laser. In addition, this study broadened the applications of MOFs in pulse laser technology and introduced a new approach to advancing the field of ultrafast photonics.

Nanosecond pulse generation mode-locked by an artificial saturable absorber based on SMF-MMF-SMF structure

We present a noteworthy demonstration of nanosecond pulse generation utilizing an all-fiber artificial saturable absorber (SA) structure, composed of single-mode multimode single-mode fiber (SMF-MMF-SMF), integrated into a passively mode-locked erbium-doped fiber laser (EDFL). The SMS-based SA effectively phase-locked the longitudinal modes within the elongated EDFL cavity, resulting in the production of mode-locked pulses operating at 1567 nm. Mode-locking is achieved through the Kerr effect of nonlinear multimode interference. The pulse repetition rate is synchronized with the fundamental frequency at 1.28 MHz. At a pump power of 269.1 mW, the laser achieves a remarkable peak average pulse energy of 6.0 nJ. Demonstrating outstanding stability, the laser operation exhibits a peak-to-pedestal extinction ratio of 70 dB for the fundamental frequency. We are confident in the substantial potential of this SMS structure, positioning it as a compelling candidate for integration into ultrafast fiber lasers, with promising prospects in the field.

Passively harmonic mode-locked erbium-doped fiber lasers based on PbSnS2 saturable absorbers

The two-dimensional (2D) material PbSnS2, a type of transition metal dichalcogenides (TMD), is a highly anisotropic layered compound with potential applications in ultrafast optics. We prepared PbSnS2 nanosheets by liquid phase exfoliation, attached them to microfibers to fabricate saturable absorbers (SAs) by optical deposition method, and successfully applied them to a passive erbium-doped fiber laser (EDFL). In addition, the saturable absorption properties of PbSnS2-based SA were confirmed using a balanced two-detector measurement system. The results demonstrate that the PbSnS2-based SA can realize different stable mode-locked states in the same EDFL cavity, including fundamental frequency conventional soliton and 15th harmonic mode-locked states. Among them, the laser produced fundamental frequency mode-locked state with a signal-to-noise ratio of 59.51 dB (6.58 MHz repetition frequency). The HML pulse with a maximum repetition frequency of 98.71 MHz (corresponding to the 15th harmonic) was obtained. The results demonstrate that PbSnS2 is a candidate material for generating ultrafast pulses and has excellent potential for application in ultrafast lasers.

Generation of Q-switched and mode-locked pulses in erbium-doped fiber ring laser using saturable absorption of Ti2SnC

MAX phase materials have garnered significant attention due to their corrosion resistance, impressive antioxidation and high electrical and optical conductivity. One such material, Titanium Tin Carbide (Ti2SnC), has demonstrated notable nonlinear optical properties. The saturable absorption of Ti2SnC, embedded into a polyvinyl (PVA) film, was measured to assess its potential. The Ti2SnC -PVA film exhibited a calculated modulation depth of 7.8%. In the context of practical applications, the Ti2SnC-PVA film was employed as a saturable absorber (SA) in an Erbium-doped fiber laser (EDFL) cavity. This configuration enabled the generation of stable Q-switched and mode-locked pulse trains. Q-switched operation occurred in a pump power range of 51.67 mW–83.83 mW, reaching a peak pulse energy of 110.94 nJ. Transitioning to mode-locking operation, the laser cavity demonstrated efficiency in the pump power range of 105.27 mW–196.39 mW. At a pump power of 196.39 mW, the fiber laser cavity achieved its highest pulse energy of 5.42 nJ, characterized by a pulse width of 2.32 ps and a pulse repetition rate of 1.825 MHz. These results highlight the promising potential of Ti2SnC-PVA thin film as a cutting-edge material for applications in pulsed laser systems. The material's excellent nonlinear optical properties make it a compelling candidate for advancing the field of pulsed laser technology.

Copper phthalocyanines as a mode-locker in an Er-doped fiber laser.

We demonstrate a mode-locked erbium-doped fiber laser (EDFL) utilizing copper phthalocyanines (CuPc) as a saturable absorber (SA) for the first time, to the best of our knowledge. The investigated SA was prepared using a simple, low-cost and straightforward technique, whereby the CuPc powder was embedded into polyvinyl alcohol (PVA) to form a thin film. The thin film acted as a mode-locker when it was incorporated into the EDFL cavity to produce output pulses at a repetition rate of 1.8MHz with a pulse duration of 1.98ps. The frequency spectrum showed a signal-to-noise ratio as high as 55dB, which indicates the stability of the mode-locking operation. To the best of our knowledge, this is the first work to report using CuPc as a mode-locker.

Optimization of Dual-Wavelength linear cavity Erbium-Doped fiber laser based on pairs of fiber Bragg gratings

There are few reports in the field of linear cavity dual-wavelength fiber lasers about the laser output characteristics when 3-dB fiber loop mirror (FLM) and Fiber Bragg grating (FBG) are used as full reflective mirrors, respectively. Additionally, there is scarce research on further tuning of the FBG parameters (reflectivity and center wavelength interval) to study dual-wavelength fiber lasers. In this paper, we compare the performances of dual-wavelength lasing outputs between the 3-dB FLM-FBG cavity and the FBG-only cavity in a linear-cavity erbium-doped fiber laser (EDFL) based on the polarization hole burning effect. The results show that the optical signal-to-noise ratios (OSNRs) of the dual-wavelength lasing outputs with the FBG-only cavity are approximately 4 ∼ 5 dB higher than those with the 3-dB FLM-FBG cavity. Furthermore, the lasing output performances based on the FBG-only cavity are compared when the reflectivities of the output-mirror FBGs are the same or different. It is observed that the dual-wavelength laser with the same output reflectivity leads to higher OSNR, slope efficiency, and stability. Moreover, by varying the center wavelength interval of pairs of FBGs in the FBG-only cavity to values of 4 nm, 8 nm, and 12 nm respectively. It is shown that wider intervals result in higher OSNRs but lower laser slope efficiency. Finally, we demonstrate a dual- wavelength linear cavity EDFL operating at room temperature with two lasing wavelengths of 1550 nm and 1562 nm. The laser results in OSNRs around 50.62 dB and 50.93 dB; center wavelength variations of less than 0.030 nm and 0.035 nm; output power fluctuations of less than 0.061 mW and 0.059 mW, respectively.

Soliton Pulse Generation with MoS2 Saturable Absorber

We have successfully generated soliton mode-locked pulses in a ring Erbium-doped fiber laser (EDFL) cavity using molybdenum disulfide (MoS2) saturable absorber. The MoS2 thin film was grown onto ITO substrate through electro-deposition process using a mixture of 0.5M H2MoO4 and 0.5M Na2S2O3.5H2O as electrolyte solution. The EDFL produced stable soliton pulses operating at centre wavelength of 1557 nm and repetition rate of 1.88 MHz. The mode-locking was realized by injecting pump power within a range from 77 mW to 124 mW. It generates the maximum output power of 0.7 mW and pulse width of 3.0 ps.

Q-switched pulse operation in erbium-doped fiber laser subject to zirconia (ZrO2) nanoparticles-based saturable absorber

In this paper, the zirconia (ZrO2) nanoparticles-based saturable-absorber (SA) have been incorporated in an erbium-doped fiber laser (EDFL) cavity for achieving a Q-switched pulse operation. The implementation of the zirconia nanoparticles-based powder on the fiber facet was accomplished using the index-matching gel's adhesion effect. The incorporation of SA in the laser cavity yielded a stable and self-starting Q-switched operation under 19.36 mW pump power that corresponded to the emission wavelength of 1557.29 nm. Additionally, it was observed that the EDFL's emission wavelength tuned from 1557.29 nm to 1562.3 nm , and the repetition rates and pulse width ranged from 61.2 to 130 kHz and 7.9 to 3.6 μs, respectively, as the pump power was increased from 19.36 to 380.16 mW. Measured experimental results reveal that at a maximum pump power of 380.16 mW, the maximum average output power, peak power, and pulse energy were noticed to be 1.17 mW, 2.5 mW, and 9 nJ, respectively. A 52 dB suppression in side bands was found at a pump power of 380.16 mW. Moreover, the stability and threshold tolerance of the EDFL has also been discussed in detail. These findings suggest that nanoparticle-based saturable absorbers have potential applications in a pulsed source, making it easier to implement in fiber cavity-based systems.

Q-switched EDFL with copper phthalocyanines saturable absorber

We have successfully demonstrated Q-switching within the confines of an erbium-doped fiber laser (EDFL) cavity. This innovative approach leveraged copper phthalocyanines (CuPc) as a saturable absorber (SA), with the SA film made via the embedding method utilizing polyvinyl alcohol (PVA). The Q-switched EDFL achieved a minimum pulse width of 3.95 µs, a maximum pulse rate of 77.2 kHz and a maximum pulse energy of 49.2 nJ as it operated under a maximum pump power of 102.8 mW. Notably, this pioneering work marks the first instance of employing a CuPc PVA-based SA to produce a Q-switched laser within the 1.55 µm region. Our findings offer exciting prospects for advancements in Q-switched fiber laser technology.

Dark pulse generation in mode-locked Erbium-doped fiber laser with Molybdenum Aluminium Boride coated side-polished fiber

We demonstrate the generation of dark pulses from an Erbium-doped fiber laser (EDFL) using a Molybdenum Aluminium Boride (MoAlB) as a saturable absorber for the first time. Molybdenum Aluminium Boride (MoAlB) was coated onto side-polished fiber (SPF) to improve the birefringence and nonlinearity inside the EDFL cavity with net anomalous dispersion. The soliton dark pulses are obtained from the laser cavity based on cubic-quintic nonlinear Schrödinger equation (CQNLSE) mechanism. The laser operated at 1560.6 nm with a pulse duration of 152 ns and repetition rate of 1.87 MHz as the pump power is set within 200 mW to 370 mW. At the maximum pump power, the average output power and pulse energy are recorded at 6.93 mW and 3.77 nJ, respectively. We think that this research is the first to show MoAlB 's potential for dark pulse generation.

Enhanced Q-switched pulse generation at 1.5 µm in erbium-doped fiber laser using Thin-Film Dititanium Tin Carbide as a saturable absorber

In this study, we demonstrate the utilization of a saturable absorber (SA) based on the Thin-Film Dititanium Tin Carbide (Ti2SnC), a novel MAX phase material, in a Q-switched erbium-doped fiber laser (EDFL) operating at 1.5 µm. The Ti2SnC was effectively integrated with an EDFL cavity to modulate cavity loss and facilitate Q-switching. The resultant SA was produced through a synergistic combination of Ti2SnC and polyvinyl alcohol (PVA), forming a thin film. The Q-switched operation exhibited high stability, achieving an impressive signal-to-noise ratio (SNR) of 65.41 dB. The laser operated within a pump power range of 67.75 mW to 115.99 mW, correlating to a laser diode current of 130–220 mA. This resulted in output power ranging from 2.33 to 6.65 mW, exhibiting a slope efficiency of 1.57%. The Q-switched laser generated pulses at a wavelength of 1531.25 nm, with the repetition rate varying from 64.18 kHz to 105.9 kHz. This corresponded to a pulse width between 5.68 and 3.00 µs. The maximum pulse energy obtained in our study was 62.80 nJ. Additionally, the 3 dB spectral bandwidth was measured to be 1.3 nm. These experimental results highlight the potential of Ti2SnC, as a cost-effective, efficient, and practical option for saturable absorbers in Q-switched fiber lasers, thereby paving the way for further developments in photonic applications.

Neodymium oxide saturable absorber for generating Q-switched and mode-locked pulses in 1.55-micron region

Exploring new saturable absorber (SA) materials is important for the advancement fibre laser technology especially in the improving the performance of Q-switched and mode-locked fiber lasers, which have tremendous applications in areas such as material processing, telecommunications, biomedical imaging, and scientific research. Here, we prepared a layer of Neodymium Oxide (Nd2O3) film as a nonlinear optical device to obtain the Q-switched and mode-locked pulses in the Erbium-doped fiber laser (EDFL) cavity. The developed Nd2O3 film recorded excellent optical properties with the saturable absorption of 2.8%, saturation intensity of 0.8 MW /cm2 and non-saturable loss of 59.0%. By integrating the Nd2O3 film into a simple ring EDFL’s cavity, a stable and robust Q-switched laser operating at 1558 nm was realized as the pump power is set between 45 and 92 mW. The average output power improved from 4.70 to 9.57 mW as the strength of the pumping was raised from 45 to 92 mW. The repetition rate and pulse width are tunable from 71 to 89 kHz and 3.48–2.56 µs, respectively as the pump power is escalated within the same range. The fundamental frequency of electrical signal exhibits signal-to-noise ratio (SNR) of 62 dB and this signifies the excellent stability of the Q-switching operation. In an extended EDFL cavity, the Nd2O3SA can produce a mode-locked soliton pulse operating at 1559.29 nm. The laser run at repetition rate of 1.89 MHz and pulse duration of 3.73 ps while recorded the highest peak power of 1.7 kW at pump power of 97.62 mW.

Silver indium selenide composite as a saturable absorber for passive Q-switched and mode-locked pulsed generation in erbium-doped fiber laser

We have successfully accomplished a Q-switched and mode-locked pulse in an Erbium-doped fiber (EDF) laser cavity by integrating a new composite material silver doped Indium Selenide (Ag/In2Se3)-based saturable absorber (SA). Ag/In2Se3 film was synthesized by using pulsed laser ablation and a common dry cast method to form a free-standing thin film SA. This SA device exhibits a nonlinear optical property of modulation depth, saturable intensity, and non-saturable loss of 2.27%, 847.20 MW/cm2, and 16.82% respectively. By implementing Ag/In2Se3 film into the EDF laser cavity, a Q-switched pulsed began to generate at a threshold pump power of 27.63 mW. Then as 100 m single-mode fiber (SMF) was implemented into the EDF laser cavity, a traditional soliton pulse began to appear with 1.873 MHz, at the threshold pump power of 76.63 mW with a narrow pulse width of 3.11 ps, and remarkable temporal stability, as demonstrated by a signal noise ratio (SNR) of 79.62 dB. The peak power of 2.61 kW was recorded. This contribution further verifies the improved optical qualities of the Ag/In2Se3 composite and offers a new possibility for developing broadband SA devices for various photonics applications.

Femtosecond mode-locked 1.5 μm fiber laser based on PEDOT: PSS as saturable absorber

We have successfully demonstrated the soliton mode-locked pulse generation in a 77 m long erbium-doped fiber laser (EDFL) cavity using Poly(3,4-ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT: PSS) as a saturable absorber (SA). The prepared PEDOT:PSS SA film exhibits excellent optical characteristics with large saturable absorption of 40% and low saturation intensity of 0.17 MW/cm2, appropriate for the soliton mode-locking generation. The fundamentally mode-locked EDFL operates at 1568.55 nm central wavelength, 2.465 MHz repetition frequency, a 3.06 nm 3-dB bandwidth and 4.46 nJ highest pulse energy.

MAX phase (Mo2Ti2AlC3) as a mode-locker for ultrafast fiber laser

We developed an ultrafast fiber laser using MAX phase material, Mo2Ti2AlC3, as a saturable absorber (SA). Mo2Ti2AlC3 was drop casted onto a side-polished fiber to act as a SA in an erbium-doped fiber laser cavity. A soliton pulse train was successfully obtained via a mode-locking mechanism. It operated at 1561.3 nm with a repetition rate of 1.8 MHz and a pulse duration of 1.2 ps when a pump light was launched into the cavity at a range between 14.8 mW and 106.4 mW. The signal-background noise ratio of the laser was extremely high at 72.9 dB. We believe that this paper is the first that demonstrates the novel application of Mo2Ti2AlC3 as a promising SA.

Zinc Oxide Nanoparticles-Poly(vinyl) Alcohol Thin Film for Generation Q-Switched Erbium-Doped Fiber Laser

The nonlinear optical property of Zinc oxide (ZnO) nanoparticles thin film synthesized by the solution casting method was investigated from the continuous wave to the Q-switching using an erbium-doped fiber laser cavity. Our laser experiment shows that ZnO nanoparticles embedded with polyvinyl alcohol (PVA) allow for the generation of a stable Q-switching laser pulse, centered at 1560.08nm with a 3-dB spectral bandwidth of 0.941 nm, a pulse duration of 3.53 µs and a high pulse energy of 171 nJ. Our finding suggests that ZnO nanoparticles thin film can be a useful nonlinear optical material for laser photonics devices such as passive q-switching for applications involving high energy.

Fiber laser with dual-channel and a selectable comb filter based on Vernier effect of parallel-connected two Mach–Zehnder interferometers

We propose and demonstrate the implementation and application of a new configuration of an all-fiber comb filter based on the Vernier effect produced by parallel-connected two in-line Mach–Zehnder interferometers (MZIs). Each in-line MZI was fabricated by fusion splicing a section of panda-type polarization maintaining fiber (PMF) with peanut-shaped tapers between two single-mode fibers. These two in-line MZIs, respectively, form reference and sensing interferometers, which are parallel-connected by two 3-dB optical fiber couplers to realize the Vernier effect. By incorporating the proposed comb-filter into the erbium-doped fiber laser cavity, two output channels at 1533.2 and 1558.2 nm have been achieved. Further, the combination of the parallel-connected two in-line MZIs and polarization controllers (PC1 and PC2) promotes the lasing in a switchable and selective way. To the best of the authors’ knowledge, this is the first demonstration of a comb filter that employs paralleled two peanut-shaped MZIs in PMF. The experimental results indicate that the proposed filter has the potential to be used in communication systems.

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.

Linewidth Narrowing of a Dual Wavelength-Selectable, Ring Cavity Erbium-Doped Fiber Laser Using a Saturable Absorber

The narrow linewidth fiber laser is useful in applications such as fiber sensing, optical communications, and spectroscopy. This paper presents an investigation of the model and an experiment of a stable, wavelength-selective, narrow linewidth, ring cavity erbium-doped fiber laser incorporating two fiber Bragg gratings (FBG) at 1530.18 nm and 1550.08 nm, respectively. An F-P tunable filter was used to select a specific wavelength after optimizing the spectral output from the two FBGs to measure their respective linewidths. The erbium-doped ring fiber laser was optimized by adjusting the optical cavity loss using a variable optical coupler at a coupling ratio of 95%. The variable coupler was set to an optimal coupling ratio of 95%, where the spectral output powers of 3.4 mW at 1530.18 nm and 3.1 mW at 1550.08 nm were achieved as the optimal fiber laser output powers. The balanced output power had an optical signal-to-noise ratio of (OSNR) of 61 dB for each wavelength. The linewidth was measured for both wavelengths without saturable absorbers, and 27.7 kHz and 28.3 kHz for 1530.18 nm and 1550.08 nm were obtained. Using the saturable absorber, the linewidths were narrowed to 25.3 KHz and 21.1 kHz for 1530.18 nm and 1550.08 nm, respectively.