Maximum Pump Power Research Articles

Utilization of group 10 2D TMDs-PdSe2 as a nonlinear optical material for obtaining switchable laser pulse generation modes

In-plane anisotropic two-dimensional (2D) materials have gained considerable interest in the field of research, due to having the potential of being used in different device applications. Recently, among these 2D materials, group 10 transition metal dichalcogenides (TMDs) pentagonal Palladium diselenide (PdSe2) is utilized in various sections of researches like nanoelectronics, thermoelectric, spintronics, optoelectronics, and ultrafast photonics, owing to its high air stability and broad absorption spectrum properties. In this paper, it is demonstrated that by utilizing this novel 2D layered PdSe2 material as a saturable absorber (SA) in an EDF laser system, it is possible to obtain switchable laser pulse generation modes. At first, the Q-switching operation mode is attained at a threshold pump power of 56.8 mW at 1564 nm, where the modulation range of pulse duration and repetition rate is 18.5 μs–2.0 μs and 16.4 kHz–57.0 kHz, respectively. Afterward, the laser pulse generation mode is switched to the mode-locked state at a pump power of 63.1 mW (threshold value) by changing the polarization condition inside the laser cavity, and this phenomenon persists until the maximum pump power of 230.4 mW. For this mode-locking operation, the achieved pulse duration is 766 fs, corresponding to the central wavelength and 3 dB bandwidth of 1566 nm and 4.16 nm, respectively. Finally, it is illustrated that PdSe2 exhibits a modulation depth of 7.01%, which substantiates the high nonlinearity of the material. To the best of the authors’ knowledge, this is the first time of switchable modes for laser pulse generation are achieved by using this PdSe2 SA. Therefore, this work will encourage the research community to carry out further studies with this PdSe2 material in the future.

2.8 µm passively Q-switched Er:ZBLAN fiber laser with an Sb saturable absorber mirror

A Q-switched Er:ZBLAN fiber laser operating at 2.8 µm was realized by employing Sb as the saturable material. The Sb material was deposited on a gold mirror by the magnetron-sputtering deposition method to develop a saturable absorber mirror (SAM). By employing the Sb-SAM in an Er:ZBLAN fiber laser, stable Q-switching operation was achieved at central wavelength of 2799.7 nm with the repetition rates ranging from 33.3 to 58.8 kHz and the pulse duration ranging from 5.7 to 1.7 µs. The Sb-SAM still works stably under the maximum pump power of 5.6 W, with an output power of 59 mW corresponding to the pulse energy of 1.03 µJ. To our knowledge, this was the first demonstration of Sb-based saturable material in Er:ZBLAN fiber laser for mid-infrared Q-switched pulse generation operating in the 2.8 µm regime, indicating its potential applications in the mid-infrared waveband.

Nanosecond semiconductor disk laser emitting at 496.5 nm

An optically pumped semiconductor disk laser based on a heterostructure containing ten CdS/ZnSe coupled quantum wells with type-II band offsets is studied. The structure was grown by metalorganic vapour phase epitaxy (MOVPE) on a GaAs substrate. The peak power of the semiconductor disk laser achieved at room temperature under longitudinal pumping by a repetitively pulsed N2 laser was 0.75 W at a wavelength of 496.5 nm, a pulse duration of 3 ns, and a pulse repetition rate of 100 Hz. The slope efficiency of the disk laser was 2.7 %. The total divergence angle at a cavity length of 1.1 mm varied from 5 mrad near the lasing threshold to 15 mrad at the maximum pump power.

Rose gold nanoparticles film for generating Q-switched and mode-locked pulses

Passively Q-switched and mode-locked Erbium doped fiber lasers have been successfully realized by using rose gold nanoparticles, which were embedded into polyvinyl alcohol as saturable absorber. The stable Q-switched laser was obtained at 1565.21 nm wavelength operation when a tiny piece of the prepared rose gold film was sandwiched between two fiber ferrules and incorporated into the proposed laser cavity. Q-switched pulses were obtained within a pump power range from 141.33 to 190.61 mW. At the maximum pump power, the laser operated at repetition rate of 84.75 kHz and pulse width of 4.16 µs while producing the highest single pulse energy of 12.81 nJ. By incorporating an additional 200 m long single-mode fiber into the laser cavity, stable mode-locked pulses were generated. It operated at repetition rate of 0.97 MHz, pulse width of 2.25 ps, maximum pulse energy of 3.12 nJ and a signal-to-noise ratio (SNR) of 63.81 dB.

Passively Q-switched multiple visible wavelengths switchable YVO4 Raman laser

The output characteristics of orange-yellow-green emission switchable output generated in a compact passively Q-switched YVO4 Raman laser were investigated for the first time. A Cr4+:YAG/YAG composite crystal was adopted as the saturable absorber to realize passively Q-switch operation. The diode-end-pumped Nd:YAP laser operating at 1.08 μm was used to drive an a-cut YVO4 crystal for realizing the first-Stokes wavelength at 1.2 μm. Selective frequency mixing of the first-Stokes and the fundamental waves in a shared cavity were achieved by an angle-tuned BBO crystal. Under an incident pump power of 12.05 W, the average maximum output powers of 472 mW for 597.4 nm orange light, 431 mW for 567.2 nm yellow light and 803 mW for 539.9 nm green light could be switchable output with respective pulse widths of about 2.6, 2.4 and 37.6 ns. Under the maximum incident pump power, the pulse repetition frequency and the single pulse energy were approximately 11.6, 10.9, 13.4 kHz and 40.7, 39.5, 59.9 μJ, respectively.

GENERATION OF Q-SWITCHED AND SOLITON MODE-LOCKED PULSES WITH BISMUTH TELLURITE SATURABLE ABSORBER

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.

Multiwavelength Brillouin Generation in Bismuth-Doped Fiber Laser With Single- and Double-Frequency Spacing

Multiwavelength fiber lasers operating in the 1.3 μm wavelength region are of great interest as they complement existing systems in the conventional optical communication band of 1.55 μm. In this work, a multiwavelength Brillouin fiber laser with single- and double-Brillouin frequency spacings operating in 1.3 μm is proposed and demonstrated using a dispersion compensating fiber (DCF) as the Brillouin gain medium. A bismuth-doped fiber serves as the laser gain medium. At the maximum pump power of 1021 mW and with the Brillouin pump set at 11 dBm, up to 7 Brillouin Stokes lines with a wavelength spacing of 0.074 nm are obtained in the single-spaced configuration. In the case of the double-spaced configuration, 14 Stokes lines are generated with a wavelength spacing of 0.15 nm between the even Stokes lines. By tuning the central wavelength of the Brillouin pump, both laser configurations are wavelength-tunable with a range of 93 nm and 19 nm for the single-spaced and double-spaced Brillouin lasers respectively. This is, to the best of the author's knowledge, the first demonstration of a multiwavelength/Brillouin laser using a bismuth-doped fiber as the laser gain medium.

Fiber Bragg gratings fabricated by femtosecond lasers for narrow-linewidth fiber laser

A narrow-linewidth erbium-doped fiber laser based on the fiber Bragg gratings (FBGs) fabricated was proposed and demonstrated experimentally. A pair of FBGs with reflectivity of 92 % and 10 %, respectively, at the center wavelength of 1580 nm were inscribed in standard SMF-28 fibers without hydrogen loading by femtosecond laser point-by-point directly writing method, which was used as mirrors for wavelength selection of fiber laser, gratings full width at half maximum (FWHM) was less than 0.15 nm. A simple linear-cavity fiber laser was realized based on gain medium, pump source and FBGs. When gain medium of Er-doped fiber is selected 8 m, a stable single wavelength of 1579 nm laser with a 3 dB linewidth of 0.06 nm was obtained. Its output power is 24.1 mW when the maximum pump power is 600 mA, and its single wavelength of 1579 nm is consistent with the central wavelength of the fabricated FBGs. This type of laser source shows real promise for applications in coherent optical frequency domain reflectometry and high resolution fiber sensor systems.

Laser gain module small-signal gain increase due to suppression of parasitic generation with pump geometry optimization

A method for optical pump scheme optimization for a laser gain module with pulsed diode arrays for Nd:YAG rods (Ø10 × 130 mm & Ø10 × 160 mm) is presented. The goal is to maximize the small-signal gain of the laser gain module while maintaining a flat-top amplification profile. A possible way of the overall small-signal gain reduction due to amplified spontaneous emission is discussed and a method to deal with this phenomenon is given. As a result of optical pump scheme optimization, the gain module with the maximum pump power of 40 kW for 250 µs pulse duration at repetition rates of up to 25 Hz is created. The maximum small-signal gain G = 100 at 1.064 is achieved.

Passively Q-switched S+/S band fiber laser with copper telluride saturable absorber

A Q-switched S-band fiber laser based on a thulium-fluoride fiber gain medium and copper telluride (Cu2Te) based saturable absorber (SA) is demonstrated. The Cu2Te based SA is fabricated as a thin film and at the maximum pump power, the generated Q-switched output has a minimum pulse width of 3.2 µs and highest pulse energy of 56.7 nJ. The pulse train varies from 20.9 kHz to 30.2 kHz at the highest pump power. The wavelength of the generated output can be tuned over a range of 32 nm from 1470 nm to 1502 nm. The demonstrated laser has a high potential for industrial applications focusing on the S-band region.

Inducing Q-switching operation at 1-micron all-fiber laser via lutetium oxide film saturable absorber

We demonstrated a rare-earth element of lutetium oxide (Lu2O3) as a passive saturable absorber (SA) for generating Q-switching operation laser at 1-micron region. The laser cavity is all-fiber ring configuration with a single-clad ytterbium-doped fiber as a gain medium. Under drop-casting fabrication method, the Lu2O3 film with a 20 μm thickness has a linear absorption of ∼ 5 dB. A stable pulse train with a typical pattern of repetition rate (26.25 kHz–46.68 kHz) and pulse width (9.36 μs to 4.59 μs) presence along the increment of pump power from 116 mW to 151 mW. At maximum pump power, the single pulse envelope has a pulse energy of 128.8 nJ with 42 dB signal-to-noise ratio (SNR). The maximum output power is 6 mW and the laser consistently has a peak wavelength at 1067.8 nm. Exploring a new alternative material for saturable absorber is one of direction for better pulse all-fiber laser development, especially at 1-micron region wavelength.

Tungsten trioxide (WO3) film absorber for generating soliton mode-locked pulses in erbium laser

We proposed a new type of passive saturable absorber (SA) based on tungsten trioxide (WO3)- polyvinyl alcohol (PVA) film for generation of soliton mode-locked pulse in the erbium-doped fiber laser (EDFL) cavity. The WO3-PVA has a modulation depth of 20% with a saturable intensity of 0.04 W/cm2. 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 WO3 is a promising nonlinear optical material for application in generating ultra-fast mode-locked laser. This is the first time that WO3 was utilized as SA in the 1.5 μm region.

Q-switched and tunable wavelength fiber laser utilizing nickel oxide saturable absorber and sagnac loop mirror filter

We demonstrate a Q-switched Erbium-doped fiber laser (EDFL) with a tunable output wavelength using Nickel oxide (NiO) saturable absorber (SA) in conjunction with a Sagnac loop mirror (SLM) filter. The proposed SA was prepared by embedding NiO nanoparticles obtained bysimplistic sonochemical reaction into polyethylene oxide (PEO). The NiO PEO film was integrated into a figure-of-eight resonator configured with a SLM to generate Q-switched pulses with a tunable output wavelength. As the SLM temperature was increased from 30 °C to 70 °C, the laser operation can be tuned from 1551.9 nm to 1544.1 nm. At 1551.9 nm operation, the repetition rate rose from 36.2 kHz to 40.3 kHz and the pulse duration reduced from 10.00 to 9.32 μs when the pump power rose from 131.5 to 161.0 mW. At the highest pump power of 161.0 mW, the maximum output power and pulse energy were obtained at 0.67 mW and 16.6 nJ. For Q-switched operation at 1544.1 nm, the produced Q-switched pulse exhibited a pulse duration of 8.88 μs, the repetition rate of 45.7 kHz, the highest output power of 0.60 mW and pulse energy of 13.1 nJ at the maximum pump power of 161.0 mW.

Copper nanowires based mode-locker for soliton nanosecond pulse generation in erbium-doped fiber laser

A mode-locked nanosecond Erbium-doped fiber laser (EDFL) based on copper nanowires (CuNWs) saturable absorber (SA) is successfully demonstrated in this article. The CuNWs were prepared by dissolving the CuNWs solution in a polydimethylsiloxane (PDMS) host polymer. Through the doctor blade technique, a free-standing CuNWs-PDMS film was formed. Upon inserting the film in a laser cavity, nanosecond pulses with a stable mode-locking was observed past the threshold pump power of 104.62 mW. The laser operated at the center frequency of 1.86 MHz and wavelength of 1563.3 nm. At the maximum available pump power of 187.04 mW, the 173 ns mode-locked pulse train achieved the highest pulse energy of 9.14 nJ and the maximum average output power of 1.703 mW. These results vindicate the capacity of the CuNWs film SA in producing nanosecond mode-locked EDFL in the 1550 nm region.

GeSe Evanescent Field Saturable Absorber for Mode-Locking in a Thulium/Holmium Fiber Laser

A mode-locked Thulium-Holmium doped fiber laser (THDFL) with a Germanium Selenide (GeSe) saturable absorber (SA) is demonstrated for operation in the 2.0 μm wavelength region. The SA device is fabricated by drop-casting the GeSe onto an arc-shaped fiber which is then incorporated into the THDFL to induce mode-locked pulses. Stable mode-locking is attained at 1908.78 nm, with pulse duration of 1.67 ps and output power of 2.74 mW at a maximum pump power of 476 mW. The results of this work show that the GeSe can be a viable alternative for ultrafast photonics applications in the 2.0 μm. region.

56 nm Wide-Band Tunable Q-Switched Erbium Doped Fiber Laser with Tungsten Ditelluride (WTe2) Saturable Absorber

A wide-band and tunable Q-switched erbium-doped fiber (EDF) laser operating at 1560.5 nm with a tungsten ditelluride (WTe2) saturable absorber (SA) is demonstrated. The semi-metallic nature of WTe2 as well as its small band gap and excellent nonlinear optical properties make it an excellent SA material. The laser cavity uses an 89.5 cm long EDF, pumped by a 980 nm laser diode as the linear gain while the WTe2 based SA generates the pulsed output. The WTe2 based SA has a modulation depth, non-saturable loss and saturation intensity of about 21.4%, 78.6%, and 0.35 kW/cm2 respectively. Stable pulses with a maximum repetition rate of 55.56 kHz, narrowest pulse width of 1.77 µs and highest pulse energy of 18.09 nJ are obtained at the maximum pump power of 244.5 mW. A 56 nm tuning range is obtained in the laser cavity, and the output is observed having a signal to noise ratio (SNR) of 48.5 dB. The demonstrated laser has potential for use in a large number of photonics applications.

Tunable passively Q-switched erbium-doped fiber laser based on Ti3C2Tx MXene as saturable absorber

Abstract The passive generation of Q-switched pulses in an erbium-doped fiber (EDF) laser using a Ti3C2Tx MXene based saturable absorber (SA) was demonstrated. The SA was formed using Ti3AlC2 MAX phase as a precursor for Ti3C2Tx MXene which was obtained by etching Ti3AlC2 using a mixture of lithium fluoride and hydrochloric acid. The generated pulse output was obtained at a central wavelength of 1563 nm with a signal to noise ratio (SNR) of 51.1 dB at a pump power of 244.5 mW. Varying the pump power from 130.1 mW to 244.5 mW resulted in corresponding changes in the repetition rates and the pulse durations from 29.76 kHz to 48.74 kHz and 2.74 µs to 1.18 µs respectively. A pulse energy of 82.06 nJ was also obtained at the maximum pump power. Stable Q-switching could be observed up to 44 nm tuning range starting from 1532 nm to 1576 nm. The generated outputs indicated that the Ti3C2Tx based SA can generate high quality and stable Q-switched pulses in the EDF laser cavity, and has high potential for use in various optical telecommunications applications.

Dual-wavelength rectangular pulses in a mode-locked ytterbium-doped fiber laser

We demonstrate dual wavelength rectangular pulses in an ytterbium-doped fiber laser in a simple, all-fiber standing wave cavity configuration. The laser cavity consists of a nonlinear optical loop mirror as a saturable absorber at one end and two fiber Bragg gratings at the other end at wavelengths of 1025 and 1055 nm. There are three distinct regimes of operation in the cavity with an increase in the pump power, one where only 1025 nm wavelength pulses appear, then both 1025 and 1055 nm pulses are supported in the cavity after that, only 1055 nm wavelength pulses are present in the cavity. In the intermediate pumping regime, two sets of pulses are supported in the cavity. These pulses move in the cavity at different speeds and on the cross-over there is no interaction in the pulses. The mode-locked pulses at the 1025 nm wavelength are polarized, whereas pulses corresponding to 1055 nm are nearly unpolarized. Pulses corresponding to both the wavelength bands exhibit a dissipative soliton resonance signature. The laser generates 60 mW total average output power at the maximum pump power of 260 mW at a ∼1.8 MHz repetition rate. The presented cavity mechanism can be utilized to generate various dual- or multi-wavelength mode-locked pulses.

Bismuth‐doped fiber as Q‐switcher in hafnium bismuth erbium co‐doped fiber laser

AbstractWe demonstrate a compact, all‐fiber Q‐switched hafnium bismuth erbium co‐doped fiber laser based on bismuth‐doped fiber (BDF) as the saturable absorber (SA). The laser cavity was constructed using a homemade hafnium bismuth erbium co‐doped fiber as gain medium. It was found that stable Q‐switched pulses operating at 1531.74 nm can be readily generated when the 980 nm pump power is raised above the threshold of 96 mW. By increasing the pump power to the maximum power of 198 mW, the repetition rate was tunable from 27.2 to 59.1 kHz while the pulse width reduces from 36.3 to 6.8 μs. At the maximum pump power, the Q‐switched laser produced a pulse energy of 10.1 nJ. The finding provides evidence of the possibility of BDF as an effective SA for Q‐switched laser operating in 1.5 μm region.

Q-„switched tunable ytterbium-doped fiber laser with molybdenum ditelluride-based saturable absorber

A Q-switched ytterbium-doped fiber laser incorporating a molybdenum ditelluride saturable absorber for operation at 1046 nm is demonstrated. The laser cavity has a low Q-switching threshold of ∼48 mW. At the maximum pump power, the laser is able to generate pulses with a duration, repetition rate, and output power of 4.88 μs, 39.6 kHz, and 0.76 mW, respectively, as well as a pulse energy of 18.9 nJ. The output of the laser can be tuned from 1064 to 1099 nm, giving a tuning range of 35 nm. The generated pulses have a signal-to-noise ratio of around 60 dB. No interference frequency components or spectral modulation is observed, indicating that the proposed system is highly stable and suitable for use as a fiber laser source in the 1.0-μm region.