Graphene Saturable Absorber Research Articles

1.61 μm high-order passive harmonic mode locking in a fiber laser based on graphene saturable absorber.

We demonstrate a passive mode-locked Er:Yb doped double-clad ring fiber laser based on graphene saturable absorber. By adjusting the polarization controller and minimizing the cavity loss, the laser can operate at hundreds of harmonics of the fundamental repetition frequency of the resonator with the central wavelength of 1.61 μm. Up to 683rd harmonic (which corresponds to 5.882 GHz) of the fundamental repetition frequency was achieved.

A single-frequency, graphene-based passively Q-switched Tm : YAP laser

We report a single-frequency, passively Q-switched Tm : YAP laser using a volume Bragg grating (VBG) as the spectral selective element, and graphene as the saturable absorber (SA). A stable single-frequency pulse laser with line width of about 4.2 MHz at central wavelength of 1988.8 nm was obtained. The average output power of the single-frequency pulse laser was measured as 724 mW, corresponding to the single pulse energy of 7.5 μJ with the repetition rate of 96.2 kHz. This project provides a simplified and low-cost laser design to obtain single-frequency pulse laser by using VBG and graphene SA.

Stable high-energy Q-switched resonantly diode-pumped Er:YAG laser at 1645 nm

We demonstrate the generation of a stable high-energy Q-switched resonantly diode-pumped Er:YAG laser at 1645nm in passive and active operation modes. For the passively Q-switched Er:YAG laser, the bi-layer graphene saturable absorber (SA), which was transferred onto the highly reflective cavity mirror by an improved method, was applied to deliver a stable pulse train with per-pulse energy of about 0.1mJ. While in the active operation mode, the voltage-ON-type rubidium titanyl phosphate (RTP) Pockels cell as an electro-optic (EO) Q-switcher allows for the generation of a stable Q-switched pulse with per-pulse energy of up to 7.5mJ. Our work may provide a basis for the development of a high-energy Er:YAG laser at 1645nm to fulfill specific applications.

Microfiber-based, highly nonlinear graphene saturable absorber for formation of versatile structural soliton molecules in a fiber laser.

We reported on the generation of versatile soliton molecules in a fiber laser mode-locked by a microfiber-based graphene saturable absorber (GSA). By virtue of the highly nonlinear effect of the microfiber-based GSA, the soliton molecules could be easily observed. In addition to regular soliton molecules, it is found that the "soliton atoms" in molecules could exhibit different characteristics and show ultra-narrow pulse separations, which was termed as 'structural soliton molecule'. The pulse profiles of 'structural soliton molecules' were further reconstructed theoretically. The obtained results would give further insight towards understanding the dynamics of soliton molecules in fiber lasers.

Broadband Graphene Saturable Absorber for Pulsed Fiber Lasers at 1, 1.5, and 2 μm

Ultrafast fiber lasers with broad spectral coverage are in great demand for a variety of applications, such as spectroscopy, and biomedical diagnosis. Graphene is an ideal ultrawide-band saturable absorber. We report broadband (up to ~1000 nm) ultrafast pulse generation from three fiber lasers mode-locked by a single graphene saturable absorber device. The mode-locked pulses were based on Yb-, Er- and Tm:Ho-doped fiber lasers at the central wavelength of 1035, 1564, and 1908 nm, respectively. The maximum output energy is up to 16.2 nJ at 1908 nm. It is the first time that ultrafast fiber lasers covering 1, 1.5, and 2 μm spectral region are mode-locked with a single graphene device. Our results validate the intrinsic broadband operation property of graphene devices for all major fiber laser wavelengths from 1 to 2 μm.

Femtosecond pulse generation with voltage-controlled graphene saturable absorber.

We report, for the first time to our knowledge, the demonstration of a graphene supercapacitor as a voltage-controlled saturable absorber for femtosecond pulse generation from a solid-state laser. By applying only a few volts of bias, the Fermi level of the device could be shifted to vary the insertion loss, while maintaining a sufficient level of saturable absorption to initiate mode-locked operation. The graphene supercapacitor was operated at bias voltages of 0.5-1V to generate sub-100 fs pulses at a pulse repetition rate of 4.51 MHz from a multipass-cavity Cr(4+):forsterite laser operating at 1255 nm. The nonlinear optical response of the graphene supercapacitor was further investigated by using pump-probe spectroscopy.

Doubly passively Q-switched Nd:GGG laser with a monolayer graphene saturable absorber and GaAs wafer

A doubly passively Q-switched Nd:GGG laser with monolayer graphene and GaAs wafer working as saturable absorbers is presented, in which the GaAs wafer also works as the output coupler. At the maximum incident pump power of 7.69 W, the obtained output power, the pulse duration and the pulse repetition rate are 820 mW, 1.06 ns, and 21.5 kHz, respectively, corresponding to pulse energy of 38.2 μJ and peak power of 35.9 kW, respectively.

Q‐switched thulium‐doped fibre laser operating at 1900 nm using multi‐layered graphene based saturable absorber

A stable passive Q-switched thulium-doped fibre laser (TDFL) operating at the 1900 nm region is demonstrated by using a multi-layer graphene film-based saturable absorber (SA). The graphene is synthesised by electrochemical exfoliation of graphite at room temperature in 1% sodium dodecyl sulphate aqueous solution. Graphene flakes obtained from the process are mixed with polyethylene oxide as the host polymer to produce free standing composite thin film which acts as a passive Q-switcher in the TDFL ring cavity. At 793 nm pump power of 186 mW, the TDFL generates an optical pulse train with a repetition rate of 7.5 kHz, pulse width of 19.7 μs and a pulse energy of 66.6 nJ. A higher performance Q-switched TDFL could be achieved with the optimisation of the graphene SA and the laser cavity.

Efficient laser emission from cladding waveguide inscribed in Nd:GdVO(4) crystal by direct femtosecond laser writing.

We report on the fabrication of depressed cladding waveguides in Nd:GdVO(4) laser crystal by using femtosecond laser inscription. The cross section of the structure is a circular shape with a diameter of 150 μm. Under the optical pump at 808 nm, the continuous wave (cw) as well as pulsed (Q-switched by graphene saturable absorber) waveguide lasing at 1064 nm has been realized, supporting guidance of both TE and TM polarizations. The maximum output power of 0.57 W was obtained in the cw regime, while the maximum pulse energy of the pulsed laser emissions was up to 19 nJ (corresponding to a maximum average output power of 0.33 W, at a resonant frequency of 18 MHz). The slope efficiencies achieved for the cw and pulsed Nd:GdVO(4) waveguide lasers were as high as 68% and 52%, respectively.

Tunable graphene saturable absorber with cross absorption modulation for mode-locking in fiber laser

Graphene saturable absorbers (GSAs) have been widely applied in ultra-fast mode-locked fiber lasers. Thanks to the broadband advantage of graphene, we theoretically and experimentally demonstrate the variation of the modulation depth of GSA by employing the effect of cross absorption modulation. This method provides an easy and efficient way to modulate the characteristics of GSA. By varying the modulation power, we realize an all-fiber fundamental mode-locked fiber laser and a harmonic mode-locked fiber laser with tunable output pulse width. Results show that the output pulse widths of the two fiber lasers can be tuned more than 40%, and the lasers have high wide application potential on nonlinear optical bio-imaging and offer an advantageous front end for extreme-power laser technologies.

Passively Q-switched 2 μm Tm:YAP laser based on graphene saturable absorber mirror.

Using high-quality single-layer graphene as a saturable absorber, Tm:YAlO₃ (Tm:YAP) crystal as the gain medium, we demonstrated a laser-diode-pumped, compact, passively Q-switched (PQS) solid-state laser in the 2 μm region. The maximum average output power was 362 mW, with the corresponding largest pulse repetition rate and pulse energy of 42.4 kHz and 8.5 μJ, respectively. Under the same pump power, the pulse width of 735 ns was obtained, which is, to our best knowledge, the shortest pulse width among Tm-doped solid-state PQS lasers using graphene saturable absorber mirrors.

Compression of the self-Q-switching in semiconductor disk lasers with single-layer graphene saturable absorbers

We demonstrate the first use of single layer graphene for compressing self-Q-switching pulses in semiconductor disk lasers. The gain region of the semiconductor disk laser used InGaAs quantum wells with a central wavelength of 1030 nm. Due to self saturable absorption of the quantum wells, the disk laser emitted at the self-Q-switching state with a pulse width of 13 μs. By introducing the single layer graphene as a saturable absorber into the V-shaped laser cavity, the pulse width of the self-pulse was compressed to 2 μs with a lower pump power of 300 mW. As the pump power was increased, multiple pulses with the pulse width of 1.8 μs appeared. The compression factor was about 7.2.

Graphene saturable absorber for diode pumped Yb:Sc2SiO5 mode-locked laser

Abstract High-quality monolayer graphene was successfully fabricated by chemical vapor deposition technology. By using the graphene as a saturable absorber, the Yb:Sc 2 SiO 5 crystal passively mode-locked laser was demonstrated for the first time. Stable mode-locked laser pulses were obtained with a repetition rate of 90.7 MHz and an average output power of 480 mW at the center wavelength of 1062.8 nm. The maximum single pulse energy and the maximum peak power were 5.3 nJ and 378 W, respectively.

Graphene-based, ultrafast Er-doped fiber laser with linearly polarized output pulses

We demonstrate an all-fiber, Er-doped fiber laser mode-locked with a graphene-based saturable absorber. The resonator is designed using only polarization maintaining fibers and components, which allows to achieve linearly polarized output beam. The laser delivers 595 fs long pulses at 1560 nm center wavelength with 6.3 nm bandwidth and 67 MHz repetition rate. As a saturable absorber, a graphene-polymer composite was used. Full Text: PDF References Q. L. Bao, H. Zhang, Y. Wang, Z. H. Ni, Z. X. Shen, K. P. Loh, D. Y. Tang, "Atomic-Layer Graphene as a Saturable Absorber for Ultrafast Pulsed Lasers", Adv. Funct. Mater. 19, 3077 (2009). CrossRef T. Hasan, Z. Sun, F. Wang, F. Bonaccorso, P. H. Tan, A. G. Rozhin, A.C. Ferrari, "Nanotube?Polymer Composites for Ultrafast Photonics", Adv. Mater. 21, 3874 (2009). CrossRef H. Zhang, D. Y. Tang, L. M. Zhao, Q. L. Bao, and K. P. Loh, "Large energy mode locking of an erbium-doped fiber laser with atomic layer graphene", Opt. Express 17, 17630 (2009). CrossRef Z. Sun, T. Hasan, F. Torrisi, D. Popa, G. Privitera, F. Wang, F. Bonaccorso, D. M. Basko, A. C. Ferrari, "Graphene Mode-Locked Ultrafast Laser", ACS Nano 4, 803 (2010). CrossRef Z. Sun, D. Popa, T. Hasan, F. Torrisi, F. Wang, E. JR Kelleher, J. C Travers, V. Nicolosi, A. C Ferrari, "A stable, wideband tunable, near transform-limited, graphene-mode-locked, ultrafast laser", Nano Res. 3, 653 (2010). CrossRef D. Popa, Z. Sun, F. Torrisi, T. Hasan, F. Wang, and A. C. Ferrari, "Sub 200 fs pulse generation from a graphene mode-locked fiber laser", Appl. Phys. Lett. 97, 203106 (2010). CrossRef H. Zhang, D. Y. Tang, L. M. Zhao, Q. L. Bao, K. P. Loh, B. Lin, and S. C. Tjin, "Compact graphene mode-locked wavelength-tunable erbium-doped fiber lasers: from all anomalous dispersion to all normal dispersion", Laser Phys. Lett. 7, 591 (2010). CrossRef H. Zhang, Q. Bao, D. Tang, L. Zhao, and K. Loh, "Large energy soliton erbium-doped fiber laser with a graphene-polymer composite mode locker", Appl. Phys. Lett. 95, 141103 (2009). CrossRef J. Xu, S. Wu, H. Li, J. Liu, R. Sun, F. Tan, Q.-H. Yang, P. Wang, "Dissipative soliton generation from a graphene oxide mode-locked Er-doped fiber laser", Opt. Express 20, 23653 (2012). CrossRef P.L. Huang, S. Lin, C. Yeh, H. Kuo, S. Huang, G. Lin, L. Li, C. Su, W. Cheng, "Stable mode-locked fiber laser based on CVD fabricated graphene saturable absorber", Opt. Express 20, 2460 (2012) CrossRef X.H. Li, Y.G. Wang, Y.S. Wang, Y.Z. Zhang, K. Wu, P.P. Shum, X. Yu, Y. Zhang, Q.J. Wang, "All-normal-dispersion passively mode-locked Yb-doped fiber ring laser based on a graphene oxide saturable absorber", Laser Phys Lett. 10, 075108 (2013). CrossRef M. Zhang, E. J. R. Kelleher, F. Torrisi, Z. Sun, T. Hasan, D. Popa, F. Wang, A. C. Ferrari, S. V. Popov, and J. R. Taylor, "Tm-doped fiber laser mode-locked by graphene-polymer composite" Opt. Express 20, 25077 (2012). CrossRef Q. Wang, T. Chen, B. Zhang, M. Li, Y. Lu, and K. P. Chen, "All-fiber passively mode-locked thulium-doped fiber ring laser using optically deposited graphene saturable absorbers", Appl. Phys. Lett. 102, 131117 (2013). CrossRef G. Sobon, J. Sotor, I. Pasternak, A. Krajewska, W. Strupinski, K. M. Abramski, "Thulium-doped all-fiber laser mode-locked by CVD-graphene/PMMA saturable absorber", Opt. Express 21, 12797 (2013). CrossRef G. Sobon, J. Sotor, I. Pasternak, K. Grodecki, P. Paletko, W. Strupinski, Z. Jankiewicz, K.M. Abramski, "Er-Doped Fiber Laser Mode-Locked by CVD-Graphene Saturable Absorber", J. Lightwave Technol. 30, 2770 (2012). CrossRef A. Martinez, K. Fuse, B. Xu, and S. Yamashita, "Optical deposition of graphene and carbon nanotubes in a fiber ferrule for passive mode-locked lasing", Opt. Express 18, 23054 (2010). CrossRef Y. M. Chang, H. Kim, J. H. Lee, and Y. Song, "Multilayered graphene efficiently formed by mechanical exfoliation for nonlinear saturable absorbers in fiber mode-locked lasers", Appl. Phys. Lett. 97, 211102 (2010). CrossRef A. Martinez, K. Fuse, and S. Yamashita, "Mechanical exfoliation of graphene for the passive mode-locking of fiber lasers", Appl. Phys. Lett. 99, 121107 (2011). CrossRef G. Sobon, J. Sotor, K. M. Abramski, "All-polarization maintaining femtosecond Er-doped fiber laser mode-locked by graphene saturable absorber", Laser Phys. Lett. 9, 581 (2012). CrossRef J. Sotor, G. Sobon, K. M. Abramski, "Scalar soliton generation in all-polarization-maintaining, graphene mode-locked fiber laser", Opt. Lett. 37, 2166 (2012). CrossRef M. L. Dennis, I. N. Duling III, "Experimental study of sideband generation in femtosecond fiber lasers", IEEE J. Quantum Electron. 30, 1469 (1994) CrossRef

Large-energy, wavelength-tunable, all-fiber passively Q-switched Er:Yb-codoped double-clad fiber laser with mono-layer chemical vapor deposition graphene.

We demonstrate a large-energy, wavelength-tunable, all-fiber passively Q-switched Er:Yb-codoped laser using a mono-layer chemical vapor deposition (CVD) graphene saturable absorber (SA). By exploiting the large laser gain of Er:Yb double-clad fiber and optimizing the coupling ratio of the output coupler, not only can the mono-layer CVD graphene SA be protected from oversaturation and thermal damage, but also a large pulse energy up to 1.05μJ (corresponding to the average output power of 25.6mW) is thus achieved. Using a tunable fiber Fabry-Perot filter, stable Q-switched pulses can operate with a tunable range from 1530.97 to 1546.92nm, covering a wavelength range of ∼16 nm. The Q-switching states at the different lasing wavelengths have been observed and recorded. The Q-switched repetition rate and the pulse duration (with the minimum one of 2.6μs) have been characterized as well. This is, to the best of our knowledge, the largest pulse energy from an all-fiber graphene Q-switched laser.

High-power ultrafast Nd:YVO4 laser mode-locked by graphene saturable absorber

Abstract The large-area monolayer graphene film was grown on Cu foil by chemical vapor deposition (CVD) technique. After transferring it to a quartz substrate, the graphene film was used as a saturable absorber (SA) in an Nd:YVO4 laser. Mode-locked laser pulses of 7.6 ps were obtained at a central wavelength of 1064 nm. Under a pump power of 6.7 W, the average output power reached a high value of 2.5 W, corresponding to an optical-to-optical efficiency of 37.3% and a slope efficiency of 40.3%. The pulse repetition rate was 87.4 MHz and the maximum pulse energy was as high as 28.6 nJ. To date, this might be the highest average output power for mode-locked laser by using graphene SA. Our results illustrate that graphene can potentially be employed in the practical low-cost and high-power mode-locking laser system.

Direct growth of graphene on quartz substrate as saturable absorber for femtosecond solid-state laser

We present a novel method for the direct metal-free growth of graphene on quartz substrate. The direct-grown graphene yields excellent nonlinear saturable absorption properties and is demonstrated to be suitable as a saturable absorber (SA) for an ultrafast solid-state laser. Nearly Fourier-limited 367 fs was obtained at a central wavelength of 1048 nm with a repetition rate of 105.7 MHz. At a pump power of 7.95 W, the average output power was 1.93 W and the highest pulse energy reached 18.3 nJ, with a peak power of 49.8 kW. Our work opens an easy route for making a reliable graphene SA with a mode-locking technique and also displays an exciting prospect in making low-cost and ultrafast lasers.

Nanosecond pulse generation in a graphene mode-locked erbium-doped fiber laser

We demonstrate a mode-locked nanosecond erbium-doped fiber laser (EDFL) using a graphene-based saturable absorber (SA). The laser directly produces nanosecond pulses with pulse duration of 24ns, repetition rate of 5.78MHz and central wavelength of 1569.5nm. The mode-locking is self-starting and the pulse train has no transient effects or signs of Q-switched behavior. The formation mechanism of nanosecond pulses emitted from the laser could be attributed to the pulse duration broadening induced by the large lumped normal dispersion of the graphene SA. Such nanosecond pulse duration as well as megahertz repetition rate makes this mode-locked all-fiber laser a suitable seed oscillator for chirped pulse amplifications and high-power applications.

Dual-wavelength rectangular pulse Yb-doped fiber laser using a microfiber-based graphene saturable absorber.

We reported on the generation of dual-wavelength rectangular pulses in a Yb-doped fiber laser (YDFL) by using a microfiber-based graphene saturable absorber (GSA). The duration of dual-wavelength rectangular pulse could be varied from 1.41 ns to 4.23 ns with the increasing pump power. With a tunable bandpass filter, it was found that the characteristics of the rectangular pulses centered at 1061.8 nm and 1068.8 nm are similar to each other. Moreover, the dual-wavelength switchable operation was also realized by properly rotating the polarization controllers (PCs). The demonstration of the dual-wavelength rectangular pulses from a YDFL would open some applications for fields such as spectroscopy, biomedicine and sensing research.

Sapphire-based graphene saturable absorber for long-time working femtosecond lasers.

We report a long-time working femtosecond laser using metal-free sapphire-based graphene as a saturable absorber (SA). The sapphire-based graphene yielded excellent nonlinear saturable absorption properties and was demonstrated to be suitable as an SA for an ultrafast solid-state laser. Stable mode-locked pulses of 325 fs were obtained at a central wavelength of 1032 nm with a repetition rate of 66.3 MHz. At pump power of 8.23 W the average output power was 1.78 W and the highest pulse energy reached 26.8 nJ with a peak power of 72.6 kW. Our work opens up a facile route for making reliable graphene SA in the mode-locking technique and also displays an exciting prospect in making low-cost and ultrafast lasers.