The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Feng Chen - One of the best experts on this subject based on the ideXlab platform.
-
6 5 ghz q switched mode locked Waveguide Lasers based on two dimensional materials as saturable absorbers
Optics Express, 2018Co-Authors: Ziqi Li, Chen Cheng, Yuxia Zhang, Haohai Yu, Feng ChenAbstract:Two-dimensional (2D) materials have generated great interest in the past few years opening up a new dimension in the development of optoelectronics and photonics. In this paper, we demonstrate 6.5 GHz fundamentally Q-switched mode-locked Lasers with high performances in the femtosecond laser-written Waveguide platform by applying graphene, MoS2 and Bi2Se3 as saturable absorbers (SAs). The minimum mode-locked pulse duration was measured to be as short as 26 ps in the case of Bi2Se3 SA. The maximum slope efficiency reached 53% in the case of MoS2 SA. This is the first demonstration of Q-switched mode-locked Waveguide Lasers based on MoS2 and Bi2Se3 in the Waveguide platform. These high-performance Q-switched mode-locked Waveguide Lasers based on 2D materials pave the way for practical applications of compact ultrafast photonics.
-
q switching of Waveguide Lasers based on graphene ws 2 van der waals heterostructure
Photonics Research, 2017Co-Authors: Ziqi Li, Chen Cheng, Javier Vazquez R De Aldana, Ningning Dong, Carolina Romero, Qingming Lu, Jun Wang, Feng ChenAbstract:We report on the operation of passively Q-switched Waveguide Lasers at 1 μm wavelength based on a graphene/WS2 heterostructure as a saturable absorber (SA). The gain medium is a crystalline Nd:YVO4 cladding Waveguide produced by femtosecond laser writing. The nanosecond Waveguide laser operation at 1064 nm has been realized with the maximum average output power of 275 mW and slope efficiency of 37%. In comparison with the systems based on single WS2 or graphene SA, the lasing Q-switched by a graphene/WS2 heterostructure SA possesses advantages of a higher pulse energy and enhanced slope efficiency, indicating the promising applications of van der Waals heterostructures for ultrafast photonic devices.
-
room temperature subnanosecond Waveguide Lasers in nd yvo4 q switched by phase change vo2 a comparison with 2d materials
Scientific Reports, 2017Co-Authors: Rang Li, Chen Cheng, Javier Vazquez R De Aldana, Carolina Romero, Qingming Lu, Yanxue Chen, Feng ChenAbstract:We report on room-temperature subnanosecond Waveguide laser operation at 1064 nm in a Nd:YVO4 crystal Waveguide through Q-switching of phase-change nanomaterial vanadium dioxide (VO2). The unique feature of VO2 nanomaterial from the insulating to metallic phases offers low-saturation-intensity nonlinear absorptions of light for subnanosecond pulse generation. The low-loss Waveguide is fabricated by using the femtosecond laser writing with depressed cladding geometry. Under optical pump at 808 nm, efficient pulsed laser has been achieved in the Nd:YVO4 Waveguide, reaching minimum pulse duration of 690 ps and maximum output average power of 66.7 mW. To compare the Q-switched laser performances by VO2 saturable absorber with those based on two-dimensional materials, the 1064-nm laser pulses have been realized in the same Waveguide platform with either graphene or transition metal dichalcogenide (in this work, WS2) coated mirror. The results on 2D material Q-switched Waveguide Lasers have shown that the shortest pulses are with 22-ns duration, whilst the maximum output average powers reach ~161.9 mW. This work shows the obvious difference on the lasing properties based on phase-change material and 2D materials, and suggests potential applications of VO2 as low-cost saturable absorber for subnanosecond laser generation.
-
Waveguide Lasers based on platforms of optical dielectric crystals
2016 Progress in Electromagnetic Research Symposium (PIERS), 2016Co-Authors: Feng ChenAbstract:Miniature light sources are desirable for integrated photonic devices. Dielectric crystals with diverse structures and functions are important media for various photonic and optical applications. Laser crystals serve as gain media for solid state laser systems, which have been applied for generation of wavelength bands from visible till mid-infrared. Direct processing of dielectric crystals by “physical” techniques, such as ion beam irradiation or femtosecond laser writing, has been successful used to produce Waveguide structures in laser materials. The fabricated structures, with on-demand configurations, are good candidates to achieve highly efficient Waveguide Lasers towards compact light sources. In this work, we apply ion beam technology, including techniques of ion implantation, swift heavy ion irradiation, or proton beam writing, to microprocess the well-known laser crystals of Nd:YAG, producing low-loss Waveguides with a few geometries. Other techniques like laser ablation and diamond blade dicing are applied to construct more complicated structures on the ion irradiated Nd:YAG platforms. Under optical pumps, efficient Waveguide Lasers operating in both continuous-wave (CW) and passively Q-switched regimes have been realized. The Q-switching of the Waveguide laser systems is achieved by using the well-known nanomaterials, such as graphene, WS 2 , VO 2 , black phosphorous as saturable absorbers. The obtained Lasers from the structures are with excellent features. For example, the proton beam written Waveguide Lasers are with beam diameter of only 2 µm. The shortest pulse duration at 1064nm in Q-switched system with VO 2 as saturable absorber is 700 ps in our Nd:YAG Waveguide laser systems. Our work opens a way to develop high-quality Waveguide laser systems for a number of photonic applications.
-
passively q switched Waveguide Lasers based on two dimensional transition metal diselenide
Optics Express, 2016Co-Authors: Chen Cheng, Javier Vazquez R De Aldana, Feng ChenAbstract:We reported on the passively Q-switched Waveguide Lasers based on few-layer transition metal diselenide, including molybdenum diselenide (MoSe2) and tungsten diselenide (WSe2), as saturable absorbers. The MoSe2 and WSe2 membranes were covered on silica wafers by chemical vapor deposition (CVD). A low-loss depressed cladding Waveguide was produced by femtosecond laser writing in a Nd:YAG crystal. Under optical pump at 808 nm, the passive Q-switching of the Nd:YAG Waveguide lasing at 1064 nm was achieved, reaching maximum average output power of 115 mW (MoSe2) and 45 mW (WSe2), respectively, which are corresponding to single-pulse energy of 36 nJ and 19 nJ. The repetition rate of the Q-switched Waveguide Lasers was tunable from 0.995 to 3.334 MHz (MoSe2) and 0.781 to 2.938 MHz (WSe2), and the obtained minimum pulse duration was 80ns (MoSe2) and 52 ns (WSe2), respectively.
Fuerbach Alexander - One of the best experts on this subject based on the ideXlab platform.
-
Bismuth telluride topological insulator nanosheet saturable absorbers for q‐switched mode‐locked Tm:ZBLAN Waveguide Lasers
Annalen Der Physik, 2016Co-Authors: Jiang Xiantao, Gross Simon, Guo Zhinan, Zhang Han, Fuerbach AlexanderAbstract:Nanosheets of bismuth telluride (Bi2Te3), a topological insulator material that exhibits broadband saturable absorption due to its non‐trivial Dirac‐cone like energy structure, are utilized to generate short pulses from Tm:ZBLAN Waveguide Lasers. By depositing multiple layers of a carefully prepared Bi2Te3 solution onto a glass substrate, the modulation depth and the saturation intensity of the fabricated devices can be controlled and optimized. This approach enables the realization of saturable absorbers that feature a modulation depth of 13% and a saturation intensity of 997 kW/cm2. For the first time to our knowledge, Q‐switched mode‐locked operation of a linearly polarized mid‐IR ZBLAN Waveguide chip laser was realized in an extended cavity configuration using the topological insulator Bi2Te3. The maximum average output power of the laser is 16.3 mW and the Q‐switched and mode‐locked repetition rates are 44 kHz and 436 MHz, respectively.
Magdalena Aguiló - One of the best experts on this subject based on the ideXlab platform.
-
Inkjet-printing of graphene saturable absorbers for ~2 μm bulk and Waveguide Lasers
Optical Materials Express, 2018Co-Authors: Pavel Loiko, Esrom Kifle, Magdalena Aguiló, Francesc Díaz, Josep Maria Serres, Szymon Sollami Delekta, Jakub Boguslawski, Maciej Kowalczyk, Jaroslaw Sotor, Uwe GriebnerAbstract:A technique for inkjet-printing of graphene saturable absorbers (SAs) for ~2-μm bulk and Waveguide Lasers is presented. Based on distillation-assisted solvent exchange to fabricate high-concentration graphene inks, this technique is capable of producing few-layer graphene films of arbitrary shape. Absorption saturation of graphene printed on glass is demonstrated at ~1.56 µm for picosecond and femtosecond pulses indicating a large fraction of the saturable losses. Inkjet-printed transmission-type graphene SAs are applied in passively Q-switched nanosecond thulium (Tm) microchip and planar Waveguide Lasers. The Tm microchip laser generates 136 ns / 1.2 µJ pulses at 1917 nm with a repetition rate of 0.37 MHz with a Q-switching conversion efficiency reaching 65%. The planar Waveguide laser generates 98 ns / 21 nJ pulses at 1834 nm at a repetition rate in the MHz-range. The inkjet-printing technique is promising for production of patterned SAs for Waveguide Lasers.
-
Femtosecond laser-written Tm:KLu(WO 4 ) 2 Waveguide Lasers
2017 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO Europe-EQEC), 2017Co-Authors: Esrom Kifle, Xavier Mateos, Javier R. Vázquez De Aldana, Airán Ródenas, Pavel Loiko, Sun Young Choi, Fabian Rotermund, Uwe Griebner, Valentin Petrov, Magdalena AguilóAbstract:During the past decade, femtosecond pulse direct-laser-written (fs-DLW) Waveguides in transparent materials have emerged as an enabling technology for the production of laser-active integrated photonic devices [1]. The thulium (Tm3+) ion is attractive for its eye-safe broadband emission at ∼2 μm (3F 4 → 3H 6 transition). Tm Waveguide Lasers are interesting for environmental and medical sensing applications. Monoclinic double tungstates (DTs), KRE(WO 4 ) 2 where RE = Gd, Y, or Lu, doped with Tm3+ ions, are known as excellent materials for efficient liquid-phase epitaxy (LPE) grown Waveguide Lasers at ∼2 μm [2]. In the present work, the first fs-DLW Tm:DT Waveguide laser is realized.
-
femtosecond laser written tm klu wo_4 _2 Waveguide Lasers
Optics Letters, 2017Co-Authors: Esrom Kifle, Xavier Mateos, Airán Ródenas, Pavel Loiko, Fabian Rotermund, Uwe Griebner, Valentin Petrov, Javier Vazquez R De Aldana, S Y Choi, Magdalena AguilóAbstract:Depressed-index channel Waveguides with a circular and photonic crystal cladding structures are prepared in a bulk monoclinic Tm:KLu(WO4)2 crystal by 3D direct femtosecond laser writing. The channel Waveguide structures are characterized and laser operation is achieved using external mirrors. In the continuous-wave mode, the maximum output power of 46 mW is achieved at 1912 nm corresponding to a slope efficiency of 15.2% and a laser threshold of only 21 mW. Passive Q-switching of a Waveguide with a circular cladding is realized using single-walled carbon nanotubes. Stable 7 nJ/50 ns pulses are achieved at a repetition rate of 1.48 MHz. This first demonstration of ∼2 μm fs-laser-written Waveguide Lasers based on monoclinic double tungstates is promising for further Lasers of this type doped with Tm3+ and Ho3+ ions.
-
Graphene Q-switched Tm:KY(WO4)2 Waveguide laser
Laser Physics, 2017Co-Authors: Esrom Kifle, Xavier Mateos, Pavel Loiko, Uwe Griebner, Valentin Petrov, Magdalena Aguiló, Konstantin Yumashev, A.s. Yasukevich, Francesc DíazAbstract:We report on the first Tm3+-doped double tungstate Waveguide laser passively Q-switched by a graphene saturable absorber using a 12.4 µm-thick 3 at.% Tm:KY0.58Gd0.22Lu0.17(WO4)2 epitaxial layer grown on a (0 1 0)-oriented pure KY(WO4)2 substrate. This laser generated 5.8 nJ/195 ns pulses at 1831.8 nm corresponding to a pulse repetition frequency of 1.13 MHz. These are the shortest pulses achieved in passively Q-switched Tm Waveguide Lasers. The laser slope efficiency was 9% and the Q-switching conversion efficiency reached 45%. Graphene is promising for the generation of ns pulses at ~2 µm in Tm3+-doped double tungstate Waveguide Lasers operating in the MHz-range.
-
2-μm Waveguide Lasers in monoclinic double tungstates
Proceedings of SPIE, 2013Co-Authors: Joan J. Carvajal, Xavier Mateos, Magdalena Aguiló, Carla J. Berrospe, Francesc DíazAbstract:Laser generation in the 2 μm spectral range is interesting for applications in mid-IR fingerprint applications, including remote sensing, gas detection, high resolution molecular spectroscopy, and medicine. Here, we review the different Tm 3+ -based Waveguide Lasers with emission at around 2 μm recently developed in monoclinic potassium double tungstates, including a CW mirrorless and the first Q-switched Waveguide laser based on this ion. We also investigated the influence on the Waveguide laser performance of the crystallographic plane on which the epitaxial active layer has been grown.
D P Shepherd - One of the best experts on this subject based on the ideXlab platform.
-
graphene q switched mode locked and q switched ion exchanged Waveguide Lasers
IEEE Photonics Technology Letters, 2015Co-Authors: Amol Choudhary, Pradeesh Kannan, Shonali Dhingra, Brian Durso, D P ShepherdAbstract:In this letter, we present the use of monolayer graphene saturable absorbers to produce Q-switched and Q-switched mode-locked operation of Yb and Yb:Er-doped phosphate glass Waveguide Lasers, respectively. For the 1535-nm-wavelength Yb:Er laser, the Q-switched pulses have repetition rates up to 526 kHz and contain mode-locked pulses at a repetition frequency of 6.8 GHz. The measured 0.44-nm bandwidth should allow pulses as short as $\sim 6$ ps to be generated. Maximum average output powers of 27 mW are obtained at a slope efficiency of 5% in this mode of operation. For the 1057-nm-wavelength Yb laser, Q-switched pulses are obtained with a repetition rate of up to 833 kHz and a maximum average output power of 21 mW. The pulse duration is found to decrease from 292 to 140 ns and the pulse energy increase from 17 to 27 nJ as the incident pump power increases from 220 to 652 mW.
-
ti sapphire Waveguide Lasers
Laser Physics Letters, 2007Co-Authors: Markus Pollnau, James S. Wilkinson, Robert W. Eason, Christos Grivas, L Laversenne, D P ShepherdAbstract:Titanium-doped sapphire is one of the most prominent laser materials and is appreciated for its excellent heat conductivity and broadband gain spectrum, allowing for a wide wavelength tunability and generation of ultrashort pulses. As one of the hardest materials, it can also serve as a model system for the fabrication of optical Waveguide structures in dielectric crystalline materials and applications in integrated optics. In this paper, we review the recent approaches towards gain and laser operation in Ti:sapphire optical Waveguides, including epitaxial growth, surface micro-structuring, and in-depth refractive-index modifications. Several methods including pulsed laser deposition, reactive ion etching, ion in-diffusion, light-ion implantation, and femtosecond-laser irradiation are presented and the results with respect to obtained refractive-index profiles, Waveguide propagation losses, and laser performance are discussed.
-
high power planar dielectric Waveguide Lasers
Journal of Physics D, 2001Co-Authors: D P Shepherd, Jacob I. Mackenzie, Simon Hettrick, C Li, Raymond J Beach, Scott C Mitchell, H E MeissnerAbstract:The advantages and potential hazards of using a planar Waveguide as the host in a high-power diode-pumped laser system are described. The techniques discussed include the use of proximity-coupled diodes, double-clad Waveguides, unstable resonators, tapers, and integrated passive Q switches. Laser devices are described based on Yb3+-, Nd3+-, and Tm3+-doped YAG, and monolithic and highly compact Waveguide Lasers with outputs greater than 10 W are demonstrated. The prospects for scaling to the 100 W level and for further integration of devices for added functionality in a monolithic laser system are discussed.
-
double clad structures and proximity coupling for diode bar pumped planar Waveguide Lasers
IEEE Journal of Quantum Electronics, 2000Co-Authors: C L Bonner, D P Shepherd, T Bhutta, A C TropperAbstract:We report, for the first time, fabrication of double-clad planar Waveguide structures and their use for multiwatt, diode-bar-pumped, planar Waveguide Lasers based on Nd/sup 3+/ and Yb/sup 3+/-doped YAG. The direct-bonded, five-layer structures of sapphire, YAG, and rare-earth-doped YAG have sufficient numerical aperture to capture the fast-axis divergence of a diode bar by proximity coupling with no intervening optics, leading to very simple and compact devices. The restriction of the doped region to the central core leads to diffraction-limited laser output in the guided direction. We also show that the direct-bonding fabrication process can lead to a linearly polarized output.
-
thermally bonded planar Waveguide Lasers
Applied Physics Letters, 1997Co-Authors: C T A Brown, D.c. Hanna, D P Shepherd, C L Bonner, A C Tropper, T J Warburton, H E MeissnerAbstract:A new technique for fabricating active planar Waveguide devices is reported. This process, based on the thermal bonding of precision finished crystal or glass components, allows Waveguides to be assembled from very dissimilar materials and could be applied to a wide range of solid state laser or other optical media. The Waveguide propagation losses, inferred from the laser performance, are found to be 0.7dB/cm for Nd:Y3Al5O12 bonded to Y3Al5O12, Nd:Y3Al5O12 bonded to glass, and 0.4dB/cm for Nd:Gd3Ga5O12 bonded to Y3Al5O12 devices.
Alexander Fuerbach - One of the best experts on this subject based on the ideXlab platform.
-
Actively Q-Switched integrated Waveguide Lasers
Photonics and Fiber Technology 2016 (ACOFT BGPP NP), 2016Co-Authors: Christoph Wieschendorf, Simon Gross, Josiah Firth, Leonardo Silvestri, F. Ladouceur, David J. Spence, Alexander FuerbachAbstract:Actively Q-Switched Lasers typically require bulky optical components. By incorporating a novel liquid crystal cell into a Waveguide laser cavity, an all integrated and monolithic short-pulsed laser can be realized.
-
Bismuth telluride topological insulator nanosheet saturable absorbers for q-switched mode-locked Tm:ZBLAN Waveguide Lasers
Annalen der Physik, 2016Co-Authors: Xiantao Jiang, Zhinan Guo, Simon Gross, Michael J. Withford, Han Zhang, Alexander FuerbachAbstract:© 2016 by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Nanosheets of bismuth telluride (Bi 2 Te 3 ), a topological insulator material that exhibits broadband saturable absorption due to its non-trivial Dirac-cone like energy structure, are utilized to generate short pulses from Tm:ZBLAN Waveguide Lasers. By depositing multiple layers of a carefully prepared Bi 2 Te 3 solution onto a glass substrate, the modulation depth and the saturation intensity of the fabricated devices can be controlled and optimized. This approach enables the realization of saturable absorbers that feature a modulation depth of 13% and a saturation intensity of 997 kW/cm 2 . For the first time to our knowledge, Q-switched mode-locked operation of a linearly polarized mid-IR ZBLAN Waveguide chip laser was realized in an extended cavity configuration using the topological insulator Bi 2 Te 3 . The maximum average output power of the laser is 16.3 mW and the Q-switched and mode-locked repetition rates are 44 kHz and 436 MHz, respectively.
