Q-switched Erbium-doped Fiber Laser Research Articles

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.

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.

Comparative Study of Q-Switched Erbium Doped Fibre Laser with SWCNT-PVA Saturable Absorber of Different Ratios

This paper intends to compare the performance parameters of passive Q-switched erbium-doped fibre laser (EDFL) ring cavity configuration by employing SWCNT-PVA as a saturable absorber (SA). The single-wall carbon nanotube-polyvinyl alcohol (SWCNT-PVA) SA thin film fabricated by drop-casting technique is physically characterised to understand its surface morphology and thickness. The laser diode (LD) characterisation is attained to understand the attributes of LD before inserting the SWCNT-PVA into the ring cavity. The SWCNT-PVA SA of ratios 1:1, 3:2 and 2:3 is inserted into the cavity for analysis and comparison with each other. The pulses obtained from the Q-switched laser show that SWCNT-PVA SA of ratio 2:3 is the best SA as it possesses excellent power related parameters of the highest output power of 3.45 mW and highest pulse energy of 36.12 nJ with its moderate repetition rate of 96.25 kHz and pulse width 4.76 ms. The envisaged laser is presumed to have representational implications throughout fibre optic sensing, biosensors, range finding, and other fields for better possible prospects.

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.

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.

Passively Q-switched erbium-doped fiber laser based on two-dimensional boron carbide nanoparticles as saturable absorber

Passively Q-switched erbium-doped fiber laser based on two-dimensional boron carbide nanoparticles as saturable absorber

Q-switched Erbium Doped Fiber Laser Generation Using the Kerr Effect of Multimode Interference

This work demonstrates a single mode fibre-step index multimode fibre-single mode fibre (SMS) structure as saturable absorber (SA) to generate Q-switched laser based on the Kerr-effect of multimode interference (MMI) in an Erbium-doped fibre laser (EDFL) cavity. A 156 mm length of step index multimode fibre (SIMF) was spliced directly into a ring cavity to modulate the cavity loss. By bending and applying proper pressure on the SIMF, steady Q-switched pulse was generated without strict length restriction of the SIMF. The Q-switched laser had a high repetition rate from 87 to 158 kHz, while the corresponding pulse width was low, ranging from 4.2 μs to 2.5 μs as the pump power increased from 115 to 342 mW. The signal-to-noise ratio (SNR) of the fundamental mode for the pulsed laser was about 67 dB at a central wavelength of 1530 nm. The experiment demonstrated that SMS structure can be used as stable SA to generate Q-switched laser for high power applications. It also indicated that even with large core diameter step index multimode fiber, SMS structure can be utilized to generate stable Q-switched pulsed laser with very simple cavity settings.

All-fiber Q-switched erbium-doped fiber laser generation with SMF-SIMF-SMF structure as artificial saturable absorber

A passively Q-switched Erbium-doped fiber laser (EDFL) was successfully demonstrated using SMF (single-mode fiber)-SIMF (step-index multimode fiber)-SMF or SMS structure as a saturable absorber (SA). The SMS structure operates on the Kerr-effect of multimode interference (MMI). To modulate the cavity loss, a 158 mm length of SIMF was fusion spliced into a ring cavity. By properly adjusting the in-line polarization controller (PC) that holds the SIMF, we were able to generate steady Q-switched pulses. As the input pump power increased from 115 to 343 mW, the repetition rate of the Q-switched laser increased from 87 to 158 kHz, while the corresponding pulse width decreased from 4.2 µs to 2.5 µs. The signal-to-noise ratio (SNR) of the fundamental mode for the pulsed laser was around 72 dB at a central wavelength of 1530 nm. Our results indicate that the SMS structure can be used as an SA to generate stable Q-switched EDFL with very simple cavity settings.

Q-switched erbium-doped fiber lasers with ITO thin film saturable absorbers: A comprehensive cavity configuration study

This study presents the utilization of an indium tin oxide (ITO) thin film as a saturable absorber (SA) in various cavity configurations to illustrate a Q-switched erbium-doped fiber laser (EDFL). The system is designed in three distinct configurations, including linear, single-ring, and Figure-8 cavities, by integrating ITO in the setup, which has a modulation depth of 48.04 %. The research findings highlight that the single-ring cavity design has better performance over linear and Figure-8 designs in terms of Q-switched EDFL performance. The advantage of the single-ring cavity design is demonstrated by the higher values of the repetition rate and signal-to-noise ratio, which are 37.60 kHz and 57.45 dB, respectively. Subsequently, this single-ring cavity can be employed in applications of tunable, switchable dual-wavelength systems and optical fiber sensing.

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.

Molybdenum gallium carbide saturable absorber as Q-switcher in an erbium-doped fibre laser

In this research work, molybdenum gallium carbide (Mo2Ga2C)—fabricated as a thin film via solution casting technique—was first introduced as a saturable absorber (SA) to regulate the intracavity losses in a Q-switched fibre laser. The fabricated Mo2Ga2C SA had undergone both optical and physical interpretations prior to its employment as a Q-switcher in an erbium-doped fibre laser (EDFL) ring cavity configuration, sandwiched in between the end-facets of the optical fibre ferrules. The Q-switched wavelength was observed at 1532.07 nm and the Q-switching parameters were determined, accordingly. The temporal parameters of Q-switched EDFL, which include the maximum pulse repetition rate, minimum repetition period and minimum pulse duration were indicated as 107.60 kHz, 9.29 μs, and 5.52 μs, correspondingly. The maximum output power, peak power and pulse energy of the Mo2Ga2C-PVA SA as the Q-switcher were 7.3 mW, 11.47 mW and 67.38 nJ, in accordance with a slope efficiency of 7.39 % and signal-to-noise (SNR) ratio of 57.6 dB.

Generation of Q-switched erbium-doped fiber laser using MAX phase titanium aluminum nitride Ti4AlN3

We achieved a self-induced Q-switched erbium-doped fiber laser (EDFL) operating at 1559.4 nm through the integration of a Titanium Aluminum Nitride, Ti4AlN3 MAX phase film as a saturable absorber (SA). The MAX phase was embedded into a polyvinyl alcohol (PVA) matrix, ensuring contamination-free compatibility. The SA film demonstrated a modulation depth of 17% and saturation intensity of 0.5 MW/cm². Integration of the film enabled stable Q-switching, producing pulses with 5.75 µs width at 59.2 kHz repetition rate and 29.9 – 64.7 mW pump power. Parameters included a maximum average output power of 2.34 mW, maximum pulse energy of 39.5 nJ, and highest peak power of 6.87 mW. The RF spectrum exhibited a 63 dB signal-to-noise ratio, indicating high pulse signal quality. This demonstration of Ti4AlN3 MAX phase film Q-switched fiber laser holds promise for applications including biomedicine.

Generation of dual-wavelength Q-switched laser pulses by employing Mo2Ti2AlC3 MAX phase film

In this paper, we experimentally generate dual-wavelength laser pulses from a Q-switched erbium-doped fiber laser (QS-EDFL) by utilizing molybdenum titanium aluminum carbide (Mo2Ti2AlC3) MAX Phase film. The Mo2Ti2AlC3-SA film, which belongs to the MAX phase compound, is prepared using the mechanical exfoliation. The optical and physical properties of Mo2Ti2AlC3-SA are investigated. The fabricated film has a linear absorption of 8 dB and modulation depth of 17 % at 1.55 mm region. A steady dual-wavelength Q-switched laser pulses are achieved with 1531.6 nm and 1557 nm peaks and a free spectral range (FSR) of 25.4 nm. By increasing the input pump power from 131.87 mW to 167 mW, the repetition rate of generated pulses is varied over 104 kHz to 126 kHz. At the highest input power (167 mW), the energy and output power of the obtained pulses are 87.30 nJ and 11 mW, respectively. The results reveal that the exfoliated Mo2Ti2AlC3-SA can be operated inside EDFL to produce stable pulses with dual wavelengths.

Self-induced Q-switched fiber laser using tantalum aluminum carbide as a passive modulator

A self-induced Q-switched erbium-doped fiber laser operating at 1563 nm was achieved by integrating a passive modulator based on tantalum aluminum carbide (Ta2AlC) MAX phase film embedded into polyynyl alcohol. The modulator, serving as a saturable absorber (SA), established a modulation depth of 9% and a saturation intensity of 0.3 MW cm−2. Upon integration of the film SA, a stable Q-switched fiber laser was obtained, generating pulses with a minimum width of 7.6 µs at a repetition rate of 45.1 kHz, within a pump power range of 24.9–59.7 mW. The corresponding maximum average output power, maximum pulse energy, and highest peak power were determined at 1.6 mW, 36.2 nJ, and 4.7 mW, respectively. The RF fundamental spectrum exhibited a good signal-to-noise ratio of 61 dB, indicating excellent pulse signal quality. This demonstration of Ta2AlC MAX phase film Q-switched laser may open promising possibilities for scientific applications such as material processing.

Passively Q-switched Erbium-Doped Fibre Laser Based on Graphene-Chitin Saturable Absorber

Graphene is a carbon allotrope composed of densely packed sp2-assembled carbon atoms in a honeycomb-like crystal lattice. It is widely used in various fields of materials science to develop sensors, optoelectronic devices, nanocomposites, and others due to its excellent electronic, mechanical, optical, and thermal properties. Graphene offers several advantages, including ease of fabrication, ultrafast recovery times, low fabrication cost, and low saturation intensities. Its unique zero bandgap property makes it the only material with wavelength-independent absorption, which is advantageous in generating pulsed lasers using saturable absorbers. This study investigates the performance of graphene with a chitin bio-host polymer as a saturable absorber in a 1.5 µm erbium-doped fibre laser. Graphene embedded in chitin was fabricated and utilized in a pulsed laser cavity operating in the wavelength region of 1.5 µm to enable Q-switched pulsed laser operation. The study achieved a pulse energy of approximately 19.83 nJ and a peak power of 10.72 mW. Increasing the pump power from 30.67 mW to 174.28 mW resulted in the highest repetition rate of 63.40 kHz, corresponding to the shortest pulse width of 1.74 µs. These findings have significant implications for applications requiring ultrafast precision and accuracy, such as medical laser equipment and flexible sensors.

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.

Steady Q-switched erbium-doped fiber laser pulse generation by exploiting spider silk as a passive saturable absorber

Spider silk is a biomaterial composed of natural protein that possesses unique strength and biocompatibility. Spider silk was explored for the first time that act as a potential saturable absorber (SA) for steady Q-switched erbium-doped fiber laser pulse generation around 1569 nm. The biocompatibility of spider silk SA will lead to the realization of an environment that is free from hazardous precursors and undesirable byproducts. In this study, spider silk was directly deposited onto the end face of the fiber ferrule to complete the fiberized SA assembly. In optical characteristic context, the modulation depth of spider silk SA used was 26 % and its saturation intensity was 0.02 MW/cm2. Results showed that self-started Q-switched at 30 mW threshold pump power was achieved. It was also interesting to find that the repetition rate of spider silk SA increased from 7 kHz to 29 kHz while the pulse width decreased from 32 µs to 10 µs. The signal-to-noise ratio (SNR) of the fundamental frequency was 54 dB, confirming the good stability of the pulsed laser. The highest output power and pulse energy measured at the pump power of 200 mW were 0.04 mW and 1.4 nJ respectively. In a nutshell, these results indicate that spider silk can be a viable alternative to real SA for producing laser at the 1570 nm region and spider silk-based SA can be equally with or even superior to the commonly employed SAs, which then opens up new possibilities for pulsed laser source applications.

Dual-Wavelength Passively Q-Switched Erbium-Doped Fiber Laser Incorporating Calcium Carbonate Nanoparticles as Saturable Absorber

This study experimentally demonstrates the operation of a dual-wavelength passively Q-switched erbium-doped fiber laser that incorporates CaCO3 nanoparticles as a saturable absorber (SA). The SA was prepared by using the drop-casting method, wherein CaCO3 nanoparticles were embedded in a polyvinyl alcohol (PVA) polymer to form a CaCO3/PVA film SA. The film was integrated into a ring laser cavity with a 976 nm pump to generate Q-switched pulses. The properties of the SA were examined experimentally, and its modulation depth is approximately 47%. As the pump power increased from 180 mW to 270 mW and the pulse repetition rate increased from 12.67 kHz to 21.3 kHz, the corresponding pulse width decreased from 35.27 μs to 18.74 μs. The signal-to-noise ratio was approximately 25 dB, highlighting the laser’s stability. The results indicate that the proposed CaCO3/PVA SA is suitable for realizing portable Q-switched lasers.

Passively Q-switched mode-locking Er-doped fiber laser with tunable wavelength and pulsating soliton

A passively Q-switched mode-locking erbium-doped fiber laser with tunable wavelength and pulsating soliton is demonstrated. The polarization-maintaining erbium-doped fiber, working as the gain medium, combines with nonlinear polarization rotation to form a Lyot filter in the cavity. A tapered fiber is placed between two polarization controllers to cause a significant insertion loss in the optical path, which makes it easy to generate Q-switched mode-locking (QML) pulses. The wavelength tunable QML laser is implemented simply and easily, and the tunable wavelength ranged from 1528.05 nm to 1569.55 nm, as large as 41.5 nm. In addition, a new type of QML pulse involving pulsating soliton has been discovered in the laser, which was called Q-switched harmonic mode-locking pulsating soliton (QHML-PS). We find that the harmonic order and repetition frequency increases with the rising of the pump power. Our work has tremendous significance for expanding the research and application of emerging QML fiber lasers.

Stannic oxide saturable absorbers for generating Q-switched erbium-doped fiber lasers

As a kind of transition metal oxides (TMO), stannic oxide (SnO2) has aroused extensive attention due to its direct bandgap N-type semiconductor property. However, few studies have been focused on the nonlinear property and optical modulation. Herein, passively Q-switched erbium-doped fiber lasers based on SnO2 saturable absorber (SA) are constructed and experimentally verified. To our best knowledge, this is the first report on the optical nonlinearity of SnO2 as a Q-switcher for the near-infrared fiber laser. There are two kinds of SAs fabricated by the filmy and D-shaped fiber (DF) deposition methods. A stable Q-switching operation at 1568 nm was achieved induced by the SnO2 film. After replacing SnO2 film with the SnO2-DF SA, Q-switched operations with an operating wavelength of 1532 nm was achieved. To be noted for a comparison, the performance of 1530 nm Q-switched pulses is obviously improved. Our experimental results could further promote the progress of nonlinear optic and pulsed fiber lasers.