Mode-locked Erbium-doped Fiber Laser Research Articles

Dual-wavelength erbium-doped mode-locked fiber laser based on CoPS3 saturable absorber

Dual-wavelength erbium-doped mode-locked fiber laser based on CoPS3 saturable absorber

Dual-wavelength erbium-doped mode-locked fiber laser based on CoPS3 saturable absorber

An erbium-doped mode-locked fiber laser based on CoPS3 saturable absorber was successfully constructed and ultrashort pulsed light was obtained. The CoPS3 nanosheets solution was prepared using the liquid-phase exfoliation technique, and then drop-coated onto a tapered fiber as a saturable absorber. The fiber laser based on CoPS3 saturable absorber could output conventional solitons at the central wavelengths of 1557.46 nm or 1532.12 nm, respectively, as well as simultaneously output conventional solitons at dual wavelengths of 1531.56 nm and 1557.32 nm, with the ability to switch between the three operational states. The achieved minimum pulse width was 1.59 ps. In addition to conventional solitons, the laser demonstrated the capability to generate bound-state solitons. This study highlights the effectiveness of CoPS3 as a reliable optical modulator for fiber lasers and illustrates its potential for applications in ultrafast optics.

Narrowband 10-ps-class mode-locked erbium-doped fiber laser oscillator

We demonstrate a narrowband erbium-doped fiber (EDF) laser oscillator having a linear cavity based on the design of bulk laser oscillators mode-locked by a semiconductor saturable absorber mirror (SESAM) and out coupled by a fiber Bragg grating. The EDF laser oscillator has an average power of 7.06 ± 0.04 mW with a 3 dB bandwidth of 0.37 nm and a pulse duration of ∼12 ps at a repetition rate of 50.47 MHz. A pulse energy of ∼140 pJ is the highest ever reported in SESAM mode-locked EDF laser oscillators with a nearly Fourier-limited pulse duration demonstrating power scalability of a bulk laser and compactness of a nearly all-fiber laser. The repetition rate has a free-running fluctuation of only 312 Hz over 7 h of operation making it a promising light source for application to laser spectroscopy. The long pulse duration makes this EDF laser oscillator a suitable source for seeding a high-average-power amplifier using a large mode-area photonic crystal or tapered gain fiber without the need of pulse stretching. Moreover, this laser oscillator could be an alternative solution to the development of complicated bulk narrowband laser sources suitable for building an ion trap for application to quantum computing.

Mode-locked erbium-doped fiber laser based on Cr2GaC saturable absorber

We successfully generated short pulse in an erbium-doped fiber laser (EDFL) cavity utilizing a new saturable absorber (SA) based on chromium gallium carbide (Cr2GaC). The SA film was prepared by implanting the Cr2GaC compound into a polyvinyl alcohol (PVA) matrix. Upon integration into the laser’s cavity, we achieved a stable mode-locked laser centered at 1558.24 nm. This stability was maintained within a pump power range of 53.7–95.2 mW. Operating at a fixed repetition rate of 1.82, matching the cavity length, the laser consistently delivered pulses with a duration of 3.04 picoseconds. At its peak performance with a pump power of 95.2 mW, the laser exhibited an average power output of 6.81 mW, a peak power of 1.08 W, and a pulse envelope energy of 3.74 nJ. A noteworthy aspect of our study is the exceptional stability demonstrated by the laser. This stability is evidenced by a signal-to-noise ratio of 71.7 dB for the fundamental frequency. Importantly, this research represents a significant milestone as it marks the first instance of achieving soliton pulses in a laser cavity utilizing Cr2GaC as a SA.

171st-order harmonic soliton erbium-doped fiber laser based on 2H-MoTe2 saturable absorber

We have demonstrated a high order harmonic mode-locked erbium-doped fiber laser by utilizing 2H-MoTe2 film as a saturable absorber (SA). The SA is synthesized by depositing 2H-MoTe2 film on a D-shaped fiber. The nonlinear optical properties of the 2H-MoTe2 SA are characterized, showing a modulation depth of 14.7% and a saturation intensity of 3 GW cm−2. Through optimizing the pump power and intra-cavity polarization state, a 171st-order harmonic soliton at 0.9 GHz repetition frequency with a pulse width of 1.06 ps was obtained. The fundamentally mode-locked pulse train had a pulse width of 1.03 ps and a repetition rate of 5.33 MHz. To the best of our knowledge, the 171st-order harmonic soliton is the highest operating repetition frequency that has ever been demonstrated in a 2H-MoTe2 SA mode locked fiber laser. The results indicate the potential of 2H-MoTe2 SA at high repetition rates regimes, which could benefit for future possible application.

Switchable Single- to Multiwavelength Conventional Soliton and Bound-State Soliton Generated from a NbTe2 Saturable Absorber-Based Passive Mode-Locked Erbium-Doped Fiber Laser.

As a member of transition metal dichalcogenides (TMDs), NbTe2 has a work function of 5.32 eV and a band gap of 0 eV at the Fermi level, which enables it to possess broadband absorption characteristics and has huge potential in optoelectronic devices. In this work, a combination of liquid phase exfoliation (LPE) and optical deposition methods (ODMs) were used to fabricate a NbTe2 saturable absorber (SA). Based on the NbTe2 SA, a ring passive mode-locked erbium-doped fiber laser (PML-EDFL) was constructed by adding NbTe2 SA into the laser cavity. A switchable single- to multiwavelength (dual/triple/quadruple) conventional soliton (CS) and a bound-state soliton (BS) were observed for the first time. The results reveal that NbTe2 SA has excellent saturable absorption characteristics (modulation depth of 2.6%, saturation intensity of 177.4 MW/cm2, and unsaturated loss of 63.8%) and can suppress mode competition and stabilize multiwavelength oscillation. This study expands the applications of NbTe2 nanosheets in ultrafast optoelectronics. The proposed switchable PML-EDFL has extensive applications in high-capacity all-optical communication, high-sensitivity optical fiber sensing, high-precision spectral measurements, and high-energy-efficiency photon neural networks.

Passively harmonic mode-locked erbium-doped fiber laser with a gold nanofilm saturable absorber

We demonstrate a 1.5 GHz harmonic mode-locked erbium-doped fiber laser by incorporating gold nanofilm as a saturable absorber (SA). The high-quality gold nanofilm SA fabricated by the physical vapor deposition method possesses a high modulation depth of 12.9% and a low saturation intensity of 1.69 MW/cm2 at 1.56 µm, facilitating the generation of harmonic mode-locking. The fundamental mode-locked operation was obtained at 1564.7 nm, with a pulse duration of 586 fs and a repetition rate of 34.235 MHz. At the pump power of 610 mW, 44th-order harmonic mode-locking with a repetition rate of 1.506 GHz was achieved, which is the highest yet reported in mode-locked fiber lasers using gold nanomaterials as SAs. Moreover, the gold nanofilm-based harmonic mode-locked fiber laser shows relatively high signal-to-noise ratios, high output power, and good stability. These results highlight the advantage of the gold nanofilm-based SA in realizing high repetition rate laser sources.

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.

Stable Q-switched and femtosecond mode-locked erbium-doped fiber laser based on a CuSe nanosheets saturable absorber.

Stable Q-switched and femtosecond mode-locked erbium-doped fiber laser (EDFL) have been achieved using CuSe nanosheets as novel saturable absorber (SA), where the CuSe nanosheets were prepared by a hydrothermal method. The nonlinear optical properties of CuSe nanosheets were measured using an Z-scan setup, revealing nonlinear absorption coefficients of -3.67 ± 0.22 cm GW-1 at 1560 nm. The prepared CuSe nanosheets were mixed with polyvinyl alcohol (PVA) to obtain a CuSe-PVA SA with a modulation depth of 3.8 ± 0.13%, and it was utilized to realize a Q-switched EDFL, obtaining the narrowest pulse duration of 1.29 µs and the maximum output power of 5.96 mW, which corresponds to a pulse energy of up to 103.7 nJ. In addition, CuSe nanosheets were deposited on a D-shaped fiber (DSF) to fabricate a CuSe-DSF SA with a modulation depth of 5.6 ± 0.17%, and it was utilized to realize a mode-locked EDFL. The mode-locked EDFL demonstrated a low threshold of only 42 mW, a pulse duration of 740 fs, and a maximum output power of 9.7 mW. Meanwhile, it exhibited a high signal-to-noise ratio of 72 dB. To the best of our knowledge, this is the first time of CuSe nanosheets as SA in EDFL. The results demonstrate that CuSe nanosheets are a highly promising nonlinear optical material with great potential for applications in ultrafast photonics.

Recent Advances, Applications, and Perspectives in Erbium-Doped Fiber Combs

Optical frequency combs have emerged as a new generation of metrological tools, driving advancements in various fields such as free-space two-way time–frequency transfer, low-noise microwave source generation, and gas molecule detection. Among them, fiber combs based on erbium-doped fiber mode-locked lasers have garnered significant attention due to their numerous advantages, including low noise, high system integration, and cost-effectiveness. In this review, we discuss recent developments in erbium-doped fiber combs and analyze the advantages and disadvantages of constructing fiber combs utilizing different erbium-doped mode-locked fiber lasers. First, we provide a brief introduction to the basic principles of optical frequency combs. Then, we explore erbium-doped fiber combs implemented utilizing various mode-locking techniques, such as nonlinear polarization rotation (NPR), real saturable absorber (SA), and nonlinear amplifying loop mirror (NALM). Finally, we present an outlook on the future perspectives of erbium-doped fiber combs.

Superior Performances of Q-Switched and Mode-Locked Erbium-doped Fiber Laser using Black Titanium Dioxide Thin-film Saturable Absorbers

This work reports on the improved Q-switched and mode-locked performances of black titanium dioxide (BTiO2-x) nanoparticles embedded in thin-film composite material as a saturable absorber compared to TiO2 in an erbium-doped fiber laser. The thin-film saturable absorbers were prepared by mixing the nanoparticles with polyvinyl alcohol (PVA) as a host. BTiO2-x has a better nonlinear absorption coefficient, β of -12.46 x 10-7 m/W compared to -7.15x 10-7 m/W for TIO2 determined using z-scan measurement. The laser performance was evaluated in the 85.21 mW – 126.48 mW pump power range. Upon inserting TiO2 and BTiO2-x SA in a laser cavity, the peaks of the output spectrum shifted from 1566.62 nm to 1563.24 nm and 1565.75 nm, respectively. Regarding Q-switched performances, BTiO2-x SA generates a shorter pulse width of 16.00 µs than TiO2 SA. The slope efficiency of the TiO2 SA was 11.72 %, which is higher than the slope efficiency of the BTiO2-x SA. The maximum average and peak power generated by the BTiO2-x SA were 55.67 % and 54.83 % higher than the TiO2 SA. As for mode-locked outputs, BTiO2-x SA can generate pulsed laser at a low threshold power of 62.29 mW compared to TiO2 SA. Furthermore, BTiO2-x SA produced a shorter pulse width of 5.04 ps, whereas TiO2 is 9.20 ps. This study demonstrates that BTiO2-x SA has the potential to produce ultrashort pulse width using the mode-locked technique.

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.

Automatic mode-locked fiber laser based on adaptive genetic algorithm

A modified adaptive genetic algorithm (GA) is proposed and implemented in a mode-locked erbium-doped fiber laser (EDFL) based on nonlinear polarization rotation. The algorithm combines GAs with adaptive crossover and mutation rates. As the number of iterations increases during the solving operation, the crossover and mutation rates are dynamically adjusted with the change in the fitness function value. A stretched pulse was automatically generated when the modified adaptive GA was continuously optimized to converge the intracavity polarization state to the target state. The average number of generations required to adjust from other states to stretched pulse locking is two, which is better than that afforded by the general GA. The evolution curves of the mode-locked EDFL with different crossover and mutation rates were investigated, and the results indicate the effectiveness of the proposed modified adaptive GA. This study proposes a new scheme for rapid polarization searching in automatic mode-locked fiber lasers.

Carbon nanodots derived from organo-templated zeolites for femtosecond mode-locked fiber laser

Carbon nanodots (CNDs) have been widely investigated due to their physicochemical and optical properties. However, the nonlinear saturable absorption property and its application in laser technology is rarely reported. Here, we report the CNDs as an ideal saturable absorber (SA) for ultra-stable femtosecond mode-locked fiber laser at a wavelength of 1.5 μm. The mono-sized CNDs of 2 nm are fabricated from a dipropylamine-templated zeolite precursor calcination with a temperature of 380 °C. The nonlinear saturable absorption property of the as-synthesized CNDs is investigated by using a balanced twin-detector measurement system. The modulation depth and saturable intensity are measured to be 33 % and 3.1 MW/cm2, respectively. By inputting the CNDs SA into the erbium-doped fiber laser (EDFL) ring cavity, a highly stable mode-locked EDFL with pulse width of 388 fs and single-to-noise ratio (SNR) of 84.4 dB can be obtained. In addition, stable soliton pairs with single-pulse width of 422 fs and SNR of 84.1 dB can also be achieved. These findings demonstrate that the carbon dots can be used as an ideal SA and has promising applications in ultrafast photonics.

Bidirectional mode-locked erbium-doped fiber laser based on an all-fiber gold nanofilm saturable absorber.

We demonstrate a bidirectional mode-locked erbium-doped fiber laser by incorporating gold nanofilm as a saturable absorber (SA). The gold nanofilm SA has the advantages of high stability and high optical damage threshold. Besides, the SA exhibits a large modulation depth of 26% and a low saturation intensity of 1.22 MW/cm2 at 1.56 μm wavelength band, facilitating the mode-locking of bidirectional propagating solitons within a single laser cavity. Bidirectional mode-locked solitons are achieved, with the clockwise pulse centered at 1568.35 nm and the counter-clockwise one at 1568.6 nm, resulting in a slight repetition rate difference of 19 Hz. Moreover, numerical simulations are performed to reveal the counter-propagating dynamics of the two solitons, showing good agreement with the experimental results. The asymmetric cavity configuration gives rise to distinct buildup and evolution dynamics of the two counter-propagating pulses. These findings highlight the advantage of the gold nanofilm SA in constructing bidirectional mode-locked fiber lasers and provide insights for understanding the bidirectional pulse propagation dynamics.

Switchable dual-band generation of femtosecond pulses in a mode-locked Erbium-doped fiber laser based on monolayer graphene

Switchable dual-band generation of femtosecond pulses in a mode-locked Erbium-doped fiber laser based on monolayer graphene

Dual-loss-modulated QML erbium-doped fiber laser with microfiber and NPR technique

We demonstrated a dual-loss-modulated Q-switched mode-locked (QML) erbium-doped fiber laser based on the nonlinear polarization rotation (NPR) technique with a microfiber. The microfiber served as both a highly nonlinear medium and a saturable absorber, which together with the NPR technique enables stable QML operation under significant pump power fluctuations. We evaluated the nonlinear properties of microfibers with different waist diameters. A maximum QML envelope energy of 467.15 nJ is achieved, corresponding to an average single-pulse energy of 4.06 nJ beneath the Q-switched envelope, which is 2.35 times higher than the maximum pulse energy attained with dissipative soliton mode-locking under similar pump power. In addition, the QML laser was verified by numerical simulation based on the coupled Ginzburg-Landau equation. The microfiber's customizable size enables significant variations in non-linear and saturable absorption characteristics, creating the potential for QML pulse regulation. This research provides novel insights for designing QML lasers.

Passively mode-locked fiber lasers dynamic behavior by multimode fiber polarization controller

Passively mode locked fiber lasers (PML-FLs) can produce a variety of phenomena due to the nonlinear effects. With the introduction of the nonlinear polarization rotation (NPR) and a multimode fiber polarization controller (MMF-PC), we observed nonlinear effects in our erbium-doped mode-locked fiber laser, such as the evolution of the soliton bunch to dissipates soliton resonance (DSR) pulses. In the evolution of the soliton bunch to DSR pulses, the soliton square bunch and the multi-longitudinal mode oscillation also appeared in our experiment with the increasing the pump power. To illustrate the importance of MMF-PC, a control experiment is conducted by replacing the MMF-PC with a single mode fiber PC (SMF-PC). The experimental results indicate that the MMF-PC are crucial for the evolution of soliton pairs to DSR pulses and the generation of soliton pairs. The NPR mode-locked structure is used to achieve dual-wavelength filtering, its strength-dependent non-uniform loss can effectively suppress the mode competition in the gain fibers. The MMF-PC in the mode-locked structure adds a polarization burned hole effect inside the resonator. We achieved dual-wavelength mode locking by adjusting the PC to control the birefringence and loss in the resonator.

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.