Search

We have experimentally demonstrated the mode-locked and Q-switched fibre lasers based on MXene Ti3C2Tx as a saturable absorber (SA). MXene Ti3C2Tx was obtained using selective etching and then embedded into polyvinyl alcohol (PVA) to form the thin film. A stable soliton mode-locked laser was achieved when the Ti3C2Tx film was added in the Erbium-doped fibre laser cavity, and the pump power was adjusted between 55 and 144 mW. The pulse width of mode-locked laser was obtained to be 3.68 ps, while the repetition rate was 1.89 MHz. The maximum average output power and pulse energy were measured to be 24.42 mW and 12.92 nJ. After we decreased the cavity length by removing 100 m of SMF, the same SA could produce Q-switched laser instead of mode-locked laser. The Q-switched laser operated within the pump power of 19–66 mW, having the shortest pulse width and operating wavelength of 2.6 µs and 1557 nm, respectively. [ABSTRACT FROM AUTHOR]

Q-switched and mode-locked Erbium-doped fiber lasers (EDFLs) were demonstrated using Titanium dioxide (TiO2) film as a saturable absorber (SA). The prepared SA film is cut into small piece and sandwiched between two ferrules in EDFL (EDFL) cavity to generate a stable and compact Q-switched and mode-locked pulses. By increasing the 980 nm pump power from 104.6 mW to 145.8 mW, the repetition frequency of the Q-switched EDFL increases from 81.04 kHz to 90.58 kHz while the pulse width reduces from 5.08 µs to 4.12 µs. The maximum pulse energy of 22.63 nJ is generated at the pump power of 145.8 mW. Meanwhile, selfstarting mode-locked EDFL arises as 100 m long single-mode fiber is added into the laser cavity to balance the nonlinearity and the cavity dispersion. As the pump power was raised from 145.8 to 187 mW, the repetition rate and pulse width of the pulses are almost constant of 1.86 MHz and 3.34 ps, respectively. This experiment shows that TiO2 SA can be used to generate stable Q-switched and mode-locked pulsed lasers. [ABSTRACT FROM AUTHOR]

A C-band mode-locked fibre laser incorporating a boron nitride-doped graphene oxide (BN-GO)-based saturable absorber (SA) is proposed and demonstrated. The SA is fabricated by depositing multiple layers of synthesized BN-GO nanoparticles onto the polished surface of a side-polished fibre, which is then inserted into an erbium-doped fibre laser cavity to generate the desired pulsed output. The strong nonlinear optical response and light absorption of the BN-GO nanoparticles induces the generation of a highly stable mode-locked pulse at 1567.32 nm with visible Kelly’s sidebands. The pulses have a measured repetition rate of 13.56 MHz and a pulse width of 1.18 ps at the maximum pump power of 280.5 mW. The pulses have a frequency signal-to-noise ratio of ∼53 dB, indicating a highly stable output. The proposed laser would find significant telecommunications applications, particularly for dense wavelength division multiplexing systems. [ABSTRACT FROM AUTHOR]

• Poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT: PSS) based absorber. • PEDOT: PSS spin-coated onto polyvinyl alcohol thin film as saturable absorber (SA). • The Q-switched laser operates at 1563.3 nm with the highest pulse rate of 85.91 kHz minimum pulse duration of 2.27 1.97 µs. • The minimum pulse width and maximum pulse energy are measured as 1.97 µs and 155.51 nJ. In this article, we proposed and demonstrated a Q-switched laser operating at a 1.5 µm region utilizing Poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT: PSS) spin-coated onto polyvinyl alcohol (PVA) thin film as a passive saturable absorber (SA). A stable Q-switched pulse train was successfully obtained to operate at 1563.3 nm with a 3-dB bandwidth of 1.24 nm while the highest pulse rate and the minimum pulse duration were recorded at 85.91 kHz, and 1.97 µs, respectively. The maximum average output power and pulse energy were measured to be 13.36 mW and 155.51 nJ respectively, with the highest peak power of 78.93 mW. The spin-coated PEDOT: PSS/PVA SA showed no deterioration sign even when the laser cavity was pumped at 225 mW power. This is the first time that PEDOT: PSS/PVA has been used as a SA to produce a stable Q-switched laser in 1.55 µm. [ABSTRACT FROM AUTHOR]

Dual-wavelength Q-switched Erbium-doped fiber laser (EDFL) was shown by using tungsten disulfide (WS2), which was deposited onto a micro-sphere resonator (MSR) as a saturable absorber (SA). WS2 functions to modulate the cavity loss for Q-switching while the dual-wavelength operation was realized due to MSR, which allows only two wavelengths to oscillate in the resonator. MSR with the sphere diameter of 200 μm was fabricated at the tip of a standard single mode-fiber by employing a fiber fusion splicer machine. The SA was obtained by repeatedly dropping and drying of WS2 solution onto the MSR structure to form an active thin layer. The SA was incorporated into an EDFL cavity to realize a dual-wavelength Q-switched laser operating at 1554.0 nm and 1560.7 nm. The repetition rate of the pulse train is tunable from 72.4 kHz to 85.1 kHz as the pump power is increased from 104.6 mW to 145.8 mW. At 145.8 mW pump, the minimum pulse width and maximum pulse energy were obtained at 3.47 µs and 131.4 nJ, respectively. The dual-wavelength Q-switched laser was stable and thus it is suitable for use in airborne Lidar, environmental sensing, and terahertz applications. [ABSTRACT FROM AUTHOR]

• A turmeric [1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6 heptadiene-3,5-dione] film based saturable absorber. • The turmeric film has a modulation depth of 23%. • Soliton pulses with a temporal width of 920 fs were readily obtained. • The mode-locked laser operated at repetition rate of 3.383 MHz with the maximum pulse energy of 1.67 nJ. We have successful fabricated a turmeric [1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6 heptadiene-3,5-dione] thin film with 23% modulation depth using Poly(vinyl alcohol) as a host polymer. The fabricated film was used as saturable absorber (SA) within an erbium doped fiber laser (EDFL) ring cavity, and soliton pulses with a temporal width of 920 fs were readily obtained through the mode-locking process at threshold pump power of 144 mW. The mode-locked laser operated at 1568.4 nm with a 3-dB bandwidth of 3.84 nm. At maximum input LD power of 305 mW, the mode-locked laser has a repetition rate of 3.383 MHz, a pulse width of 920 fs, the average output power of 5.67 mW, a signal-to-noise ratio (SNR) of 77 dB, and pulse energy of 1.67 nJ. To the best of the authors' knowledge this is the first demonstration using turmeric thin film based SA for ultrafast light generation. [ABSTRACT FROM AUTHOR]

We demonstrated Q-switched and soliton mode-locked pulses operating at 1569.51 nm and 1564.45 nm, respectively by using a newly developed Bismuth Telluride Polyvinyl Alcohol (Bi2Te3 PVA) film as saturable absorber (SA). By incorporating the SA into an Erbium-doped fiber laser (EDFL) cavity, Q-switched pulses were obtained within a pump power range from 101.90 to 175.82 mW. At the maximum pump power, the laser operated at repetition rate of 92.76 kHz and pulse width of 4.76 µs while producing the highest single pulse energy of 39.4 nJ. By incorporating an additional 200 m long single-mode fiber into the laser cavity, stable soliton mode-locked pulses were generated. It operated at repetition rate of 0.97 MHz with a pulse width of 2.97 ps and a signal-to-noise ratio (SNR) of 50.89 dB. [ABSTRACT FROM AUTHOR]

• Side-polished fiber with graphene oxide nanoparticles as saturable absorber. • Graphene oxide solution prepared by Hummer's technique and hydrothermally reduced. • Side-polished fiber made by polishing away single-mode fiber cladding layer section. • Highly stable mode-locked pulses at 1544.02 nm with visible Kelly's sidebands. • Pulses have pulse repetition rate of 16.79 MHz and pulse duration of 1.17 ps. In this work, the generation of highly stable mode-locked pulses from a side-polished fiber (SPF) embedded with graphene oxide (rGO) nanoparticles (NPs) is proposed and demonstrated. The rGO NPs are obtained from a graphene oxide solution prepared using Hummer's technique, before being reduced by a hydrothermal route. The rGO NPs, suspended in the form of a solution, are then drop-casted onto the SPF. The SPF is fabricated by polishing away the cladding layer of a single-mode fiber section, leaving the core exposed and allowing the evanescent field of the signal propagating through the fiber to interact directly with the NPs. The SPF is integrated into an erbium doped fiber laser (EDFL) cavity, and the strong nonlinear optical response and spectral filtering by the rGO NPs as well as total anomalous dispersion of the laser cavity generates highly stable soliton mode-locked pulses with visible Kelly's sidebands at 1544.02 nm. The output pulses have a pulse repetition rate of 16.79 MHz and pulse duration of 1.17 ps throughout the mode-locking operation range of 64.44–280.5 mW. The rGO NP coated SPF in this work demonstrates the viability and performance of the SPF for mode-locked pulse generation via evanescent field interactions. [ABSTRACT FROM AUTHOR]

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 (Nd 2 O 3) 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 Nd 2 O 3 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 Nd 2 O 3 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 Nd 2 O 3 SA 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. [ABSTRACT FROM AUTHOR]

• Generation of mode-locked pulses using an all-fiber setup in the O-band region. • The mode-locked laser had a center wavelength of 1302.3 nm. • Performance of NiPS 3 as a saturable absorber was investigated. • Ultrashort pulse width of 370 fs was obtained with a peak power of 46.2 kW. In this work, we demonstrated a mode-locked fiber laser operating in the O-band region using nickel phosphorus trisulfide (NiPS 3) as a saturable absorber (SA) for the first time. An arc-shaped fiber was coated with a layer of NiPS 3 to serve as the SA which was then integrated into a praseodymium (Pr3+)-doped fluoride fiber laser (PDFFL) cavity for signal emission at 1.3 µm. The mode-locked laser operates at a center wavelength of 1302.3 nm, around the zero-dispersion wavelength. The mode-locked PDFFL has a repetition rate and signal-to-noise ratio (SNR) of 0.403 MHz and 55 dB, respectively. Ultrashort pulses of 370 fs were generated using the NiPS 3 -SA with a pulse energy of 17.1 nJ and a peak power of 46.2 kW. The NiPS 3 -SA in our work has shown the potential of this 2D nanomaterial ability to generate mode-locked pulses at 1.3 µm, which was rarely explored. [ABSTRACT FROM AUTHOR]

• Iron pyrite (FeS 2) based absorber for ultrafast application. • The fabricated FeS 2 thin film has a saturable absorption of 6%. • A stable soliton pulse operating at a central wavelength of 1562.4 nm. • The pulse has a width of 3.01 ps, a constant rate of 1.8 MHz and an energy of 5.69 nJ. We demonstrate a passively mode-locked pulse generation in an all-fiber erbium-doped fiber laser (EDFL) ring cavity using an iron pyrite (FeS2) based saturable absorber (SA) for the first time. The laser generates a stable soliton pulse operating at a central wavelength of 1562.4 nm when the 980 nm pump power was set within 125.23 mW to 166.4 mW. At a maximum output power of 166.4 mW, the mode-locked operation has a pulse width of 3.01 ps, a constant pulse train of 1.8 MHz, an average output power of 10.65 mW, and a pulse energy of 5.69 nJ. The fundamental frequency of the laser has a signal-to-noise ratio (SNR) of 65.2 dB, indicating the stability of the soliton pulse. This work supports the use of FeS2 as a saturable absorber that can motivate further academic exploration of two-dimensional (2D) material in nonlinear optics as well as in ultrafast photonics applications. [ABSTRACT FROM AUTHOR]

• Mode-locked laser was generated using Ti 2 C MXene and Ti 2 AlC MAX Phase. • Central wavelength of Ti 2 C MXene was 1933.82 nm with pulse width of 1.655 ps. • Ti 2 AlC MAX Phase has central wavelength of 1894.54 nm with 1.382 ps of pulse width. • SNR of 70 dB and 66 dB for Ti 2 C MXene and Ti 2 AlC MAX Phase, respectively. This research provides feasibility investigations of Ti 2 C MXene and Ti 2 AlC MAX Phase materials to be used as saturable absorbers (SAs). The fabrication procedure for both SAs has been described in this paper, where both laser parameters of Ti 2 C MXene and Ti 2 AlC MAX Phase were compared in detail. Ti 2 C MXene deposited tapered fiber has a modulation depth of 4.7% and saturation intensity of 0.98 MW/cm2, whereas Ti 2 AlC MAX Phase deposited tapered fiber has corresponding values of 3.27%, 0.86 MW/cm2, respectively. The findings shows that Ti 2 C MXene can provide a stable mode-locked operation with pulse width of 1.655 ps and optical bandwidth of 2.57 nm at a center wavelength of 1933.82 nm. Similarly, the Ti 2 AlC MAX Phase produced the corresponding values of 1.382 ps, 2.75 nm, and 1894.54 nm, respectively. Additionally, Ti 2 C MXene appeared to be a better candidate based on a higher signal-to-noise ratio (SNR) value of 70 dB as compared to that of Ti 2 AlC MAX Phase at 66 dB when operating in a thulium-holmium doped fiber laser (THDFL). The Ti 2 C MXene and Ti 2 AlC MAX Phase based SAs have significant potential for photonics applications in the "eye-safe" region. [ABSTRACT FROM AUTHOR]

• Turmeric PVA film was fabricated for saturable absorber (SA) application. • Q-switched laser was achieved at 1566.96 nm. • The maximum pulse energy was 150.96 nJ. • The minimum pulse width was 725 ns. • The results indicate that the turmeric film performed better than other SAs. We report a passively Q-switched Erbium-doped fiber laser (EDFL) at 1566.96 nm by applying a new type of organic material based on turmeric as the saturable absorber (SA). The material was prepared by the embedding turmeric powder into polyvinyl alcohol (PVA) film. The prepared thin film was inserted between two fiber ferrules and integrated into an EDFL cavity to generate Q-switched pulses at threshold pump power of 119 mW. The maximum Q-switched pulse average power and pulse energy were 13.6 mW and 150.96 nJ, respectively under the input pump power of 255 mW. The highest pulse repetition rate and shortest pulse duration was 90.09 kHz and 725 ns, respectively. The finding indicates that the turmeric material has performed well as SA in the 1.5 µm spectral region. [ABSTRACT FROM AUTHOR]

• Lawsone (2-hydroxy-1,4-naphthoquinone) film was proposed as saturable absorber. • It was fabricated using liquid-phase exfoliation technique. • Q-switched pulse was realized with the lawsone saturable absorber. • Q-switched laser has the shortest pulse width of 1.7 µs, the highest pulse energy of 53 nJ. • The Q-switched laser operated at 1564 nm. In this paper, lawsone (2-hydroxy-1,4-naphthoquinone), a natural dye material is proposed and demonstrated as a saturable absorber (SA) for passive Q-switching operation in Erbium-doped fiber laser (EDFL) cavity. The lawsone-based SA was fabricated using a liquid-phase exfoliation technique. A tiny piece of the lawsone film was then cut and slot-in between two fiber ferrules so that it can easily be incorporated into a laser cavity as a Q-switcher. A stable Q-switched pulse train operation was observed with the repetition rate of 80 kHz and pulse width as narrow as 1.7 µs at 1564 nm wavelength. The maximum pulse energy and average power were obtained to be 53 nJ and 4.3 mW, respectively. The results indicate that the lawsone material can be a suitable SA for Q-switched pulse laser operating at the 1.5-µm region. To the best of our knowledge, this is the first time lawsone material is utilized as a SA device for generating Q-switched pulse. [ABSTRACT FROM AUTHOR]

This paper presents a ZnPc: PVA film as saturable absorber (SA) for Q-switched pulse generation at 1-micron region. The SA film was obtained by embedding the ZnPc into polyvinyl alcohol (PVA). It was inserted into an Ytterbium-doped fiber laser (YDFL) cavity to act as a Q-switcher. The Q-switching operation was realized at the center of wavelength of 1036 nm with the minimum pulse width of 2.2 μs. The highest repetition rate and the maximum pulse energy were obtained at 63 kHz and 91 nJ, respectively. A signal to noise ratio (SNR) as high as 49 dB was observed, which indicates a stable operation of Q-switching in the YDFL cavity. This is the first demonstration of the use of ZnPc as Q-switcher in 1-micron wavelength region. A stable and high energy Q-switched pulse was realized with the proposed SA, which was obtained with a low-cost fabrication process. [ABSTRACT FROM AUTHOR]

• 8-Hydroxyquinolino cadmium chloride hydrate (8-HQCdCl 2 H 2 O) as saturable absorber. • It has a modulation depth of 18%. • The Q-switched pulses have a duration of 726 ns and repetition rate of 150 kHz. • The mode-locked pulses have a pulse width of 1.83 ps and repetition rate of 1 MHz. In this paper, we experimentally proposed and demonstrated the application of thin-film saturable absorber (SA) based on 8-Hydroxyquinolino cadmium chloride hydrate (8-HQCdCl 2 H 2 O) material as both Q-switcher and mode-locker in the cavity of erbium-doped fiber laser (EDFL). The 8-HQCdCl 2 H 2 O was embedded in polyvinyl alcohol (PVA) to fabricate the thin-film, which has then employed in the Q-switched and mode-locked EDFL cavity for passively generating nanosecond and picosecond pulses, respectively. At the maximum pump power of 167 mW, the Q-switched laser-produced pulse train with a pulse width of 726 ns, a repetition rate of 150 kHz, and a signal-to-noise ratio (SNR) of 72 dB. We also demonstrated the generation of mode-locked picosecond pulses by adding 200 m long single-mode fiber (SMF) into the ring EDFL cavity. The mode-locked laser-generated pulses have a pulse width of 1.83 ps, a repetition rate of 1 MHz, and the SNR of 77 dB for the electrical spectrum. [ABSTRACT FROM AUTHOR]

• Demonstrating tungsten tri-oxide (WO 3) film as a new mode-locker in erbium laser. • SA was prepared by the drop and casting technology. • A stable mode-locking pulse was realized at threshold power of 50 mW. • The maximum pulse energy and pulse duration were about 1.14 nJ and 2.69 ps. We proposed a new type of passive saturable absorber (SA) based on tungsten trioxide (WO 3)- polyvinyl alcohol (PVA) film for generation of soliton mode-locked pulse in the erbium-doped fiber laser (EDFL) cavity. The WO 3 -PVA has a modulation depth of 20% with a saturable intensity of 0.04 W/cm 2. The new SA film was integrated into the cavity to realize a stable mode-locked pulses operating at 1565.08 nm within a pump power range from 50 mW to 225 mW. The pulse repetition rate and pulse width of the soliton laser was 1.85 MHz and 2.69 ps, respectively. The pulse energy of 1.14 nJ and peak power of 0.67 kW were obtained at the maximum input pump power of 225 mW. These results indicate that WO 3 is a promising nonlinear optical material for application in generating ultra-fast mode-locked laser. This is the first time that WO 3 was utilized as SA in the 1.5 μm region. [ABSTRACT FROM AUTHOR]

• Zinc phthalocyanine (ZnPc) film was fabricated for saturable absorber (SA) application. • The film was prepared in three methods; ZnPc was embedded into, casted onto and spin-coated onto the PVA film. • Q-switched laser was achieved with the three SAs. • The maximum pulse energy was 71 nJ. • The results indicate that the ZnPc materials are feasible for operation in 1.5 µm region. This paper demonstrated the use of Zinc phthalocyanine (ZnPc) thin film as saturable absorber (SA) to generate Q-switched pulse train in erbium-doped fiber laser (EDFL) cavity. The film was prepared in three methods; ZnPc was embedded into, casted onto and spin-coated onto the polyvinyl alcohol (PVA) film and the samples are referred to embedding ZnPc:PVA, casting ZnPc/PVA, and spin-coating ZnPc/PVA, respectively in this paper. The SA was inserted between two optical fiber ferrules in the laser cavity. The Q-switched fiber laser operates at a wavelength of 1561.4, 1560.4 and 1559.5 nm for embedding ZnPc:PVA, casting ZnPc/PVA, and spin-coating ZnPc/PVA SAs respectively. The pulse repetition rate increases from 25.19 to 48 kHz, 30.3 to 43 kHz, and 21.5 to 32.2 kHz as the pump power rises from 115.8 to 148 mW, 119 to 141 mW, and 109.6 to 135 mW for the SA fabrication methods of ZnPc:PVA, casting ZnPc/PVA, and spin-coating ZnPc/PVA, respectively. However, the pulse width decreases from 8.28 to 3.6 µs for embedding ZnPc:PVA, 10.8 to 4.9 µs for casting ZnPc/PVA, and 12.3 to 6 µs for spin-coating ZnPc/PVA. The results indicate that the ZnPc materials is feasible for use as SA in realizing a reliably stable and flexible Q-switching pulse lasers for 1.5 µm region. The maximum pulse energies are calculated to be 71, 32 and 50 nJ for the three SA fabrication methods of ZnPc:PVA, casting ZnPc/PVA, and spin-coating ZnPc/PVA. To the best of the authors' knowledge, this is the first time ZnPc material is used as a SA device for a stable Q-switched laser pulse operation. [ABSTRACT FROM AUTHOR]

• Holmium oxide film for Q-switched and mode-locked laser generation. • Saturable absorber was fabricated by embedding Ho 2 O 3 nanoparticles into PVA film. • 115.8 kHz Q-switched laser with the maximum pulse energy of 129.36 nJ. • Mode locked laser with repetition rate of 17.1 MHz and pulse width of 650 fs. We demonstrated a new type of transition metal oxide (TMO) material, Holmium oxide (Ho 2 O 3) polymer film SA for compact passively Q-switched and mode-locked erbium-doped fiber laser (EDFL) generations. The film SA has a thickness of ~40 µm and modulation depth of ~45%. It was fabricated by embedding Ho 2 O 3 nanoparticles into PVA polymer solution. The Q-switched laser operated stably at a center wavelength of 1563 nm within a pump power range of 45–97 mW. The maximum Q-switching pulse repetition rate and the narrowest attainable pulse width were 115.8 kHz and 0.64 µs, respectively; while, the maximum pulse energy was obtained as 129.36 nJ. On the other hand, the mode-locked EDFL emerged stably within a pump power range of 62–180 mW at a center wavelength of 1565.4 nm. The repetition rate was 17.1 MHz, while the pulse width was 650 fs. Additionally, the maximum output power was measured as 9.01 mW; while, the corresponding maximum pulse energy was obtained as 0.524 nJ. This Ho 2 O 3 film SA offers simplicity and reliability in the design of compact and portable fiber pulsed laser generators particularly in the 1.55-µm regime. [ABSTRACT FROM AUTHOR]