Er-doped Fiber Laser Research Articles

Dual-wavelength self-starting mode-locking Er-doped fiber laser with MnPS<sub>3</sub> saturable absorber

As a member of the metal phosphorus trichalcogenide family, MPS<sub>3</sub> is widely used in nonlinear optics and devices, which can be regarded as a significant benefit for the excellent photonic and optoelectronic properties. In this work, the MnPS<sub>3</sub> nanosheet is prepared by the chemical vapor transport method and the MnPS<sub>3</sub> saturable absorber is demonstrated by modifying mechanical exfoliation. To the best of our knowledge, the dual-wavelength self-starting mode-locking erbium-doped fiber laser with MnPS<sub>3</sub> saturable absorber is demonstrated for the first time. The dual wavelength mode-locked laser with a pulse repetition rate of 5.102 MHz at 1565.19 nm and 1565.63 nm is proposed. Its maximum output power at the dual-wavelength is 27.2 MW. The mode-locked laser can self-start and stably run for more than 280 h.

Realization of high-performance tri-layer graphene saturable absorber mirror fabricated via a one-step transfer process

Graphene, as a saturable absorber (SA), has attracted much attention for its application in ultrashort pulse fiber lasers due to its ultrafast interband carrier relaxation and ultra-broadband wavelength operation. Nevertheless, during the stacking process of monolayer graphene layer, the induced nonuniform contact at the interface of graphene layers deteriorate the device performance. Herein, we report the fabrication of graphene saturable absorber mirrors (SAMs) via a one-step transfer process and the realization of the much enlarged modulation depth and the much reduced nonsaturable loss with tri-layer graphene (TLG) than single-layer graphene (SLG) due to the improved uniform contact at the interface. Moreover, the operation of 1550 nm mode-locked Er-doped fiber laser with the TLG SAM exhibits excellent output characteristics of the maximum output power of 9.9 mW, a slope efficiency of 2.4% and a pulse width of 714 fs. Our findings are expected to pave the way toward high-performance ultrashort pulse fiber lasers based on graphene SAs.

Tunable optical frequency comb from a compact and robust Er:fiber laser

We report on a compact and robust self-referenced optical frequency comb with a tunable repetition rate, generated by an all-polarization-maintaining (PM) mode-locked Er-doped fiber laser. The spacing between comb teeth can be tuned above 300 kHz at a repetition rate of 101 MHz. The repetition rate and the carrier–envelope offset of the laser are stabilized separately, and the relative residual phase noises are determined to be $336~\unicode[STIX]{x03BC}\text{rad}$ and 713 mrad (1 Hz–1 MHz). The accurate frequency characteristics and the stable structure show great potential for the use of such a comb in applications of precision measurements.

Generation of 60 fs pulses at 780 nm by frequency doubling of Er-doped fiber laser with tunable repetition rate for TPEF imaging

Generation of 60 fs pulses at 780 nm by frequency doubling of Er-doped fiber laser with tunable repetition rate for TPEF imaging

Mode-locked fiber laser at 2.8 μm using a chemical-vapor-deposited WSe2 saturable absorber mirror

We demonstrate a 2.8 μm mid-infrared Er-doped ZBLAN mode-locked fiber laser by employing transition metal dichalcogenides (TMD) as a saturable absorber mirror (SAM) for the first time. The TMD-SAM with a large modulation depth of 24% was fabricated by transferring a chemical-vapor-deposited high-quality large-area few-layer WSe2 on a gold-coated mirror. Stable mode-locked pulses of 21 ps were obtained with a repetition rate of 42.43 MHz and an average output power up to 360 mW.

2.4 GHz L-Band Passively Harmonic Mode Locked Er-Doped Fiber Laser Based on Carbon Nanotubes Film

We experimentally demonstrate a passively harmonic mode locked (PHML) Er-doped fiber laser with pump power efficiency up to 17 MHz/mW operating at L-band based on single walled carbon nanotubes polyvinyl alcohol (SWCNTs-PVA) film. Under 233 mW pump power, the stable pulse train at 1594.97 nm with 40.5 dB side mode suppression ratio (SMSR) and 742 fs pulse duration is obtained at a repetition rate of 1.923 GHz, corresponding to 170th harmonic of the fundamental frequency. Under optimized intracavity conditions, the pulses frequency is able to scale up to 2.415 GHz with a high level of 40 dB SMSR, which to the best of our knowledge, is the highest value yet reported from a L-band PHML fiber laser incorporating SWCNTs as saturable absorber (SA). Such high repetition rate and stable fiber laser operating at L band may be desirable for various applications.

Experimental Studies on the Noise Properties of the Harmonics From a Passively Mode-Locked Er-Doped Fiber Laser

We experimentally investigate the noise properties of a homemade 586 MHz mode-locked laser (MLL). The variation of the timing jitter versus the harmonic order is measured, which is consistent with the theoretical analyses. The dominant contributions to the timing jitter are detailedly studied by analyzing the phase noises at different harmonic frequencies. For low-order harmonics, the intensity noise and relative-intensity-noise-coupled (RIN-coupled) jitter mainly contribute to the timing jitter, while for high-order harmonics, the amplified spontaneous emission (ASE) noise makes the dominant contribution. Then we find that a higher output ratio has an obvious improvement on reducing the timing jitter and suppressing the phase noise because of the shorter pulse duration and lower net cavity dispersion caused by the higher output ratio. Finally a comparison of the noise performance between the MLL and a commercial signal generator is made, which shows that the optically generated radio-frequency signal (OGRFS) has a lower phase noise at high offset frequencies, however the higher phase noise at low offset frequencies leads to a higher timing jitter than the commercial SG.

Ternary chalcogenide Ta2NiS5 nanosheets for broadband pulse generation in ultrafast fiber lasers

Abstract In this article, a high-quality saturable absorber (SA) based on a two-dimensional ternary chalcogenide Ta2NiS5 nanosheet has been successfully fabricated and used in 1- and 1.5-μm spectral regions to generate ultrafast laser pulses. The Ta2NiS5-based SA is fabricated by mechanical exfoliation and sandwiched between two fiber ferrules to form a fiber-compatible SA. On the basis of the twin-detector technique, nonlinear optical absorption of the Ta2NiS5-SA is characterized by 64.7% and 11.95% modulation depths with 1.3 and 0.72 MW/cm2 saturation intensities at 1028 and 1570 nm, respectively. When Ta2NiS5-SA is integrated into Yb- and Er-doped fiber laser cavities, stable self-starting Q-switched pulses are observed. Furthermore, by adjusting the cavity structure and optimizing dispersion in the cavity, we obtain hybrid mode-locking and mode-locking fiber laser operation at 1029 and 1569 nm, respectively. These results validate the performance of Ta2NiS5 as a broadband SA for the generation of ultrafast laser pulses, offering new opportunities of ternary transition-metal dichalcogenide alloys in future photonic devices.

Lead sulfide nanoparticles for dual-wavelength ultrashort pulse generation

Nanoparticle materials have many potential applications in the area of electronics and optoelectronics due to their unique and versatile properties. In particular, lead sulfide nanoparticles (PbS NPs) have shown excellent ultrafast photonics and can be applied to communication systems because of their low bandgap, high thermal damage threshold and stability. The wavelength division multiplexor (WDM) technique is vital to fiber optical communication, which allows the transmission of many different-wavelength signals in one fiber cable. However, PbS NPs for multi-wavelength pulse generation has not been reported until now. In this work, PbS NPs have been investigated and successfully applied in an Er-doped fiber laser as a saturable absorber (SA) to generate a dual-wavelength short pulse for the first time. A picosecond-level ultrashort pulse at center wavelengths of 1545 and 1585 nm can be achieved simultaneously or respectively. It is worth mentioning that the two wavelengths are separated up to 40 nm, which can significantly expand the optical communication capacity. The result suggests that PbS NPs as smart nonlinear optical components have wide applications in optical communications, short-pulse lasers, and even high-performance photodectors.

Ultrafast mode-locked fiber laser with zirconium disulfide on D-shaped fiber

Transition-metal dichalcogenides (TMDs), as highly anisotropic layered compounds, have attracted increasing interest from basic research to practical applications. Among them, zirconium disulfide (ZrS2) with remarkable physical properties has been widely investigated recently. Here, ZrS2 employed as a saturable absorber is utilized in an Er-doped fiber laser. A stable mode-locking operation is achieved, with central wavelength of ~1559.5 nm, 3 dB bandwidth of ~1.72 nm, and pulse duration of ~1.75 ps. These results make ZrS2 an appealing candidate for generating ultrafast laser pulses.

Optical characteristics and application of carbon-nanotube-based saturable absorber with a spiral scheme

A carbon-nanotube-based saturable absorber (CNT-SA) with a spiral scheme is proposed, which is obtained by twining CNT-polymer filaments around a microfiber. The proposed CNT-SA possesses many advantages, such as high thermal damage threshold, excellent oxidation resistance, and long-distance evanescent field interaction. Nonlinear absorption of this CNT-SA is measured, giving saturable absorption and saturable intensity of ∼5.02% and ∼172.2 MW cm−2, respectively. Based on the CNT-SA, an Er-doped fiber laser is achieved. The experimental results open up venues to create a new type of SA for ultrafast lasers.

Ferromagnetic insulator Cr2Ge2Te6 as a modulator for generating near-infrared bright-dark soliton pairs.

Novel two-dimensional (2D)-materials-based ultra-fast modulators exhibit significance in extending the fundamental investigations and practical applications of mode-locked fiber lasers. In our work, employing the liquid-phase exfoliation method, a ${{\rm Cr}_2}{{\rm Ge}_2}{{\rm Te}_6}$Cr2Ge2Te6 (CGT) optical modulator with a modulation depth and a saturable intensity of 1.64% and ${6.31}\,\,{{\rm MW/cm}^2}$6.31MW/cm2 was fabricated. Due to its suitable modulation properties and high nonlinear coefficient, a stable bright-dark soliton pair was successfully achieved within an Er-doped fiber laser. Under the pump power of 560 mW, the maximum average output power was 5.36 mW with a pulse repetition rate of 1.835 MHz. Our results fully present the capacity of CGT in designing bright-dark soliton operations and provide a meaningful reference for promoting the ultra-fast modulation applications of ferromagnetic insulators.

Soliton mode-locked Er-doped fiber laser by using Alq3 saturable absorber

This paper demonstrated a mode-locked fiber laser based on Alq3 as passive saturable absorber (SA) in a simple all-fiber Erbium-doped fiber laser (EDFL) cavity. By incorporating Alq3 into the fiber laser cavity, a stable mode-locked pulsing was achieved. The laser pulses have a pulse width of 1.6 ps with a soliton spectrum centered at 1561.5 nm. The pulses train exhibits a very stable output with a high signal to noise ratio (SNR) of 41.5 dB. The results suggest that Alq3 is a promising nonlinear optical material, which could be as an ultra-fast mode-locker. To the best of our knowledge, this is the first demonstration of Alq3 as a mode-locker in an EDFL setup.

Heavily Doped Semiconductor Colloidal Nanocrystals as Ultra-Broadband Switches for Near-Infrared and Mid-Infrared Pulse Lasers.

Heavily self-doped semiconductors can be designed to be used in advanced photonics due to both fabrication and functional advantages. Ultrafast response, strong optical nonlinearity, broadband wavelength range, and accessibility of integration are major challenges for ultrafast all-optical photonics to operate in the infrared wavelength range. Here, solution-processed Cu1.8Se semiconductor nanocrystals (NCs) demonstrate an ultrafast response (about 360-520 fs), strong optical nonlinearity (as large as -1.4 × 103 cm GW-1), and broadband (from 800 to 3000 nm) nonlinear optical absorption in the near-infrared and mid-infrared wavelength ranges. The ultrafast response and larger optical nonlinearity may be triggered by the plasma ground-state bleaching in the strong surface electromagnetic filed. Stable Q-switched lasers in Er-doped fiber laser, Tm-doped fiber laser, and Ho/Pr-codoped ZBLAN fiber laser are operated, respectively. These findings indicate that Cu1.8Se NCs are prospective nonlinear materials for ultrafast response and broadband pulse laser.

Harmonic Soliton Molecule: SnS Nanosheets for 105th Harmonic Soliton Molecule Generation (Ann. Phys. 10/2019)

SnS, a mysterious and fascinating two-dimensional (2D) semiconductor material, has excellent optical properties. In article number 1900273, Xiaohui Li and co-workers characterize SnS nanosheets systemically and successfully apply SnS nanosheets in an Er-doped fiber laser to achieve a 105th harmonic soliton molecule with a spectral modulation period of 1.81 nm, corresponding to the repetition frequency of 459 MHz.

170 mW-level mode-locked Er-doped fiber laser oscillator based on nonlinear polarization rotation

In our work, by optimizing the length of the cavity and using high-power home-made pump source, based on the commonly-used nonlinear polarization rotation (NPR) technique, we designed a stable all-fiber high-power Er-doped mode-locked laser successfully. The maximum average output power was as high as 174 mW under the pump power of 2659 mW. To our knowledge, 174 mW was a new record average output power of NPR based all-fiber mode-locked Er-doped fiber laser, which was much higher than the results reported previously. Our work will provide a significant reference for future demonstrations of high-power mode-locked Er-doped fiber lasers and promote the applications of mode-locked Er-doped oscillators.

Dissipative soliton generation in Er-doped fibre laser using SnS2 as a saturable absorber

Dissipative soliton generation is successfully demonstrated in an Erbium-doped mode-locked fibre laser using Tin Disulfide (SnS2) as a saturable absorber in the near-zero dispersion regime. A stable dissipative soliton pulse train operating at a wavelength of 1560 nm is successfully obtained with a 32 nm FWHM power. The 152 fs pulses were produced using 0.48 nJ of pulse energy in the all-fibre laser cavity following compression in a single-mode fibre.

In2Se3 nanosheets with broadband saturable absorption used for near-infrared femtosecond laser mode locking

Indium selenide (In2Se3) has attracted tremendous attention due to its favorable electronic features, broad tunable bandgap, high stability and other attractive properties. However, its further applications for nonlinear optics have not yet been fully explored. In this work, we demonstrate that few-layer α-In2Se3 nanosheets exhibit strong saturable absorption properties over a wide wavelength range covering 800, 1064 and 1550 nm. The few-layer α-In2Se3 nanosheets used for this experiment are fabricated via a simple ultrasonic exfoliation in liquid. Stable ultrafast mode-locking laser pulses are obtained from both ytterbium-doped and erbium-doped fiber laser systems operating at 1064 and 1550 nm, respectively. A pulse duration as short as 215 fs was achieved in the Er-doped fiber laser system. Stable output pulses over 6 h of operation were obtained in both laser systems. The pulse energy and peak power of the laser output pulses were increased by reducing the In2Se3 thickness. These results indicate that α-In2Se3 nanosheets with low layer numbers are promising candidates for broad ultrafast photonics devices, such as optical switchers, Q-switchers and mode lockers.

Harmonic Mode‐Locking: SnSe2 Nanosheets for Subpicosecond Harmonic Mode‐Locked Pulse Generation (Small 38/2019)

Tin diselenide (SnSe2) nanosheets as novel 2D layered materials have excellent optical properties. In article number 1902811, Xiao-Hui Li and co-workers characterize SnSe2 nanosheets systemically and successfully apply SnSe2 nanosheets in an Er-doped fiber laser to obtain 31th order subpicosecond harmonic mode-locking, corresponding to a 257.3-MHz repetition rate.

Improved Laser Damage Threshold of In2Se3 Saturable Absorber by PVD for High-Power Mode-Locked Er-Doped Fiber Laser.

In this study, a double-end pumped high-power passively mode-locked erbium-doped fiber laser (EDFL) was realized by employing a few-layered In2Se3 flakes as a saturable absorber (SA). Herein, the uniform large-scale In2Se3 flakes were synthesized by the physical vapor deposition (PVD) method. The PVD-In2Se3 SA exhibited a remarkable damage threshold of higher than 24 mJ/cm2. Meanwhile, the PVD-In2Se3 SA had a modulation depth and saturable intensity of 18.75% and 6.8 MW/cm2, respectively. Based on the In2Se3 SA, the stable bright pulses emitting at 1559.4 nm with an average output power/pulse energy/pulse duration of 122.4 mW/5.8 nJ/14.4 ns were obtained successfully. To our knowledge, 122.4 mW was the new major breakthrough of mode-locked Er-doped fiber lasers. In addition, this is the first demonstration of the dark-bright pulse pair generation based on In2Se3 SA. The maximum average output power of the dark-bright pulse reached 121.2 mW, which also showed significant enhancement in comparison with previous works. Our excellent experiment results fully prove the superiority of our experimental design scheme and indicate that the PVD-In2Se3 could operate as a promising highly-nonlinear photonic material for a high-power fiber laser.