The Experts below are selected from a list of 55950 Experts worldwide ranked by ideXlab platform
Ya Cheng - One of the best experts on this subject based on the ideXlab platform.
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An on-chip tunable micro-disk Laser fabricated on Er3+ doped lithium niobate on insulator (LNOI)
2020Co-Authors: Wang Zhe, Fang Zhiwei, Liu Zhaoxiang, Chu Wei, Zhou Yuan, Zhang Jianhao, Wu Rongbo, Wang Min, Lu Tao, Ya ChengAbstract:We demonstrate a C-band wavelength-tunable microLaser with an Er3+ doped high quality (~1.02x10^6) lithium niobate microdisk resonator. With a 976 nm continuous-wave Pump Laser, lasing action can be observed at a Pump power threshold as low as ~250 {\mu}W at room temperature. Furthermore, the microdisk Laser wavelength can be tuned by varying the Pump Laser power, showing a tuning efficiency of ~-17.03 pm/mW at low Pump power blow 13 mW, and 10.58 pm/mW at high Pump power above 13 mW
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second harmonic generation in a high q lithium niobate microresonator fabricated by femtosecond Laser micromachining
Science China-physics Mechanics & Astronomy, 2015Co-Authors: Yingxin Xu, Zhiwei Fang, Nengwen Wang, Lingling Qiao, Wei Fang, Min Wang, Ya ChengAbstract:We report on second harmonic generation (SHG) in on-chip high-Q (>105) lithium niobate (LiNbO3, LN) microresonators fabricated by femtosecond Laser micromachining. We examine the efficiency of SHG with either a continuous-wave (CW) or an ultrashort pulsed Pump Laser. The normalized conversion efficiencies of SHG obtained with the CW and pulsed Pump Lasers are measured to be 1.3510-5 m W-1 and 2.3010-6 m W-1, respectively.
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dynamic wavelength switching of a remote nitrogen or air Laser with chirped femtosecond Laser pulses
Laser Physics Letters, 2015Co-Authors: Chenrui Jing, Hongqiang Xie, Guihua Li, Bin Zeng, Wei Chu, Haisu Zhang, Jielei Ni, Jinping Yao, Huailiang Xu, Ya ChengAbstract:We experimentally investigate the influence of the chirp of 800 nm Ti:sapphire Pump Laser pulses on the lasing behaviors of N2+ ions for the transitions between the excited electronic B2∑u+ state (v' = 0) and the ground X2∑g+ state (v = 0,1) at wavelengths of 391 and 428 nm. We found that as the chirp of the Pump Laser pulses varies from negative to positive, the intensities of the lasing signals at 391 and 428 nm show different chirp-dependent behaviors. Namely, the coherent emission at 391 nm reaches the maximum when the chirp of the Pump pulse is transform-limited; whereas the 428 nm emission becomes strongest when the Pump pulse is negatively chirped. This observation is ascribed to different self-generated seed sources produced in the plasma channel, which is verified by introducing an external seed for a Pump–probe measurement. Our finding enables switching of wavelengths of remote lasing emissions of N2+ by manipulating the chirp of the Pump Laser pulses.
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second harmonic generation in a high q lithium niobate microresonator fabricated by femtosecond Laser micromachining
arXiv: Optics, 2014Co-Authors: Yingxin Xu, Zhiwei Fang, Jiangxin Song, Nengwen Wang, Lingling Qiao, Wei Fang, Ya ChengAbstract:We report on fabrication of high Q lithium niobate (LN) whispering-gallery-mode (WGM) microresonators suspended on silica pedestals by femtosecond Laser microfabrication. The micrometer-scale (diameter ~82 {\mu}m) LN resonator possesses a Q factor of 2.5x10^5 around 1550 nm wavelength range. Moreover, second harmonic generation with a continuous-wave tunable single-longitudinal-mode Pump Laser in the on-chip LN microresonator is demonstrated in the on-chip LN microresonator. A fiber taper is employed to couple the Pump Laser into the microresonator, showing a normalized conversion efficiency of 1.35x10^-5/mW.
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multiwavelength amplified harmonic emissions from carbon dioxide Pumped by mid infrared femtosecond Laser pulses
EPL, 2012Co-Authors: Wei Chu, Chenrui Jing, Bin Zeng, Haisu Zhang, Jinping Yao, Ya ChengAbstract:We demonstrate multiwavelength amplified harmonic emissions in carbon dioxide gas driven by intense mid-infrared femtosecond Laser pulses. The simultaneous amplified emissions at 315, 326, 337 and 351 nm from the A2Πu-X2Πg transition of CO2+ are found to have a high gain coefficient of ~4.43 cm−1 with the polarizations parallel to that of the Pump Laser. This is ascribed to the seeding effect by the third harmonic of Pump Laser. The coherence property of the amplified harmonic emissions is further evidenced by its diffraction pattern.
Evangelos Th Papaioannou - One of the best experts on this subject based on the ideXlab platform.
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optimized spintronic terahertz emitters based on epitaxial grown fe pt layer structures
Scientific Reports, 2018Co-Authors: Garik Torosyan, Sascha Keller, Laura Scheuer, R Beigang, Evangelos Th PapaioannouAbstract:We report on generation of pulsed broadband terahertz radiation utilizing the inverse spin hall effect in Fe/Pt bilayers on MgO and sapphire substrates. The emitter was optimized with respect to layer thickness, growth parameters, substrates and geometrical arrangement. The experimentally determined optimum layer thicknesses were in qualitative agreement with simulations of the spin current induced in the ferromagnetic layer. Our model takes into account generation of spin polarization, spin diffusion and accumulation in Fe and Pt and electrical as well as optical properties of the bilayer samples. Using the device in a counterintuitive orientation a Si lens was attached to increase the collection efficiency of the emitter. The optimized emitter provided a bandwidth of up to 8 THz which was mainly limited by the low-temperature-grown GaAs (LT-GaAS) photoconductive antenna used as detector and the pulse length of the Pump Laser. The THz pulse length was as short as 220 fs for a sub 100 fs pulse length of the 800 nm Pump Laser. Average Pump powers as low as 25 mW (at a repetition rate of 75 MHz) have been used for terahertz generation. This and the general performance make the spintronic terahertz emitter compatible with established emitters based on optical rectification in nonlinear crystals.
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efficient spintronic terahertz emitters based on epitaxial grown fe pt layer structures
arXiv: Applied Physics, 2017Co-Authors: Garik Torosyan, Sascha Keller, Laura Scheuer, R Beigang, Evangelos Th PapaioannouAbstract:We report on generation of pulsed broadband terahertz radiation utilizing the inverse spin Hall effect in Fe/Pt bilayers on MgO and sapphire substrates. The emitter was optimized with respect to layer thickness, growth parameters, substrates and geometrical arrangement. The experimentally determined optimum layer thicknesses were in qualitative agreement with simulations of the spin current induced in the ferromagnetic layer. Our model takes into account generation of spin polarization, spin diffusion and accumulation in Fe and Pt and electrical as well as optical properties of the bilayer samples. Using the device in a counterintuitive orientation a Si lens was attached to increase the collection efficiency of the emitter. The optimized emitter provided a bandwidth of up to 8 THz which was mainly limited by the low-temperature-grown GaAs (LT-GaAS) photoconductive antenna used as detector and the pulse length of the Pump Laser. The THz pulse length was as short as 220 fs for a sub 100 fs pulse length of the 800 nm Pump Laser. Average Pump powers as low as 25 mW (at a repetition rate of 75 MHz) have been used for terahertz generation. This and the general performance make the spintronic terahertz emitter compatible with established emitters based on nonlinear generation methods.
Ferenc Krausz - One of the best experts on this subject based on the ideXlab platform.
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high repetition rate picosecond Pump Laser based on a yb yag disk amplifier for optical parametric amplification
Optics Letters, 2009Co-Authors: Thomas Metzger, Catherine Y Teisset, Alexander Schwarz, Dirk Sutter, Alexander Killi, Reinhard Kienberger, Ferenc KrauszAbstract:We report an optically synchronized picosecond Pump Laser for optical parametric amplifiers based on an Yb:YAG thin-disk amplifier. At 3 kHz repetition rate, pulse energies of 25 mJ with 1.6 ps pulse duration were achieved with an rms fluctuation in pulse energy of <0.7% by utilizing a broadly intermittent single-energy regime in the deterministic chaos of a continuously Pumped regenerative amplifier.
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seeding of an eleven femtosecond optical parametric chirped pulse amplifier and its nd sup 3 picosecond Pump Laser from a single broadband ti sapphire oscillator
IEEE Journal of Selected Topics in Quantum Electronics, 2006Co-Authors: N Ishii, Laszlo Veisz, Catherine Y Teisset, Takao Fuji, S Kohler, K Schmid, Andrius Baltuska, Ferenc KrauszAbstract:We demonstrate direct simultaneous seeding of a few-cycle optical parametric chirped pulse amplifier (OPCPA) in the 700-1000-nm spectral range, and of a Nd:YLF amplifier emitting 30-ps pulses at 1053 nm by use of a chirped-mirror 6-fs Ti:sapphire oscillator. This approach of employing a single master oscillator to drive two power amplifiers simplifies the Pump Laser design and is applied to eliminate the timing jitter between the seed and the Pump pulses in the OPCPA chain. We show that 10 mJ fundamental picosecond Pump pulses with the intensity contrast in excess of 10/sup 4/ relative to the nanosecond Q-switched background can be achieved with the seed intensity available in the edge of the oscillator spectrum around 1053 nm. Cross-correlation measurements between the picosecond Pump and femtosecond oscillator pulses reveal no traceable timing jitter between the OPCPA Pump and seed pulses. The estimated long-term jitter of 0.3 ps is attributed to the thermal expansion of the cavity of the Nd:YLF regenerative amplifier.
Garik Torosyan - One of the best experts on this subject based on the ideXlab platform.
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optimized spintronic terahertz emitters based on epitaxial grown fe pt layer structures
Scientific Reports, 2018Co-Authors: Garik Torosyan, Sascha Keller, Laura Scheuer, R Beigang, Evangelos Th PapaioannouAbstract:We report on generation of pulsed broadband terahertz radiation utilizing the inverse spin hall effect in Fe/Pt bilayers on MgO and sapphire substrates. The emitter was optimized with respect to layer thickness, growth parameters, substrates and geometrical arrangement. The experimentally determined optimum layer thicknesses were in qualitative agreement with simulations of the spin current induced in the ferromagnetic layer. Our model takes into account generation of spin polarization, spin diffusion and accumulation in Fe and Pt and electrical as well as optical properties of the bilayer samples. Using the device in a counterintuitive orientation a Si lens was attached to increase the collection efficiency of the emitter. The optimized emitter provided a bandwidth of up to 8 THz which was mainly limited by the low-temperature-grown GaAs (LT-GaAS) photoconductive antenna used as detector and the pulse length of the Pump Laser. The THz pulse length was as short as 220 fs for a sub 100 fs pulse length of the 800 nm Pump Laser. Average Pump powers as low as 25 mW (at a repetition rate of 75 MHz) have been used for terahertz generation. This and the general performance make the spintronic terahertz emitter compatible with established emitters based on optical rectification in nonlinear crystals.
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efficient spintronic terahertz emitters based on epitaxial grown fe pt layer structures
arXiv: Applied Physics, 2017Co-Authors: Garik Torosyan, Sascha Keller, Laura Scheuer, R Beigang, Evangelos Th PapaioannouAbstract:We report on generation of pulsed broadband terahertz radiation utilizing the inverse spin Hall effect in Fe/Pt bilayers on MgO and sapphire substrates. The emitter was optimized with respect to layer thickness, growth parameters, substrates and geometrical arrangement. The experimentally determined optimum layer thicknesses were in qualitative agreement with simulations of the spin current induced in the ferromagnetic layer. Our model takes into account generation of spin polarization, spin diffusion and accumulation in Fe and Pt and electrical as well as optical properties of the bilayer samples. Using the device in a counterintuitive orientation a Si lens was attached to increase the collection efficiency of the emitter. The optimized emitter provided a bandwidth of up to 8 THz which was mainly limited by the low-temperature-grown GaAs (LT-GaAS) photoconductive antenna used as detector and the pulse length of the Pump Laser. The THz pulse length was as short as 220 fs for a sub 100 fs pulse length of the 800 nm Pump Laser. Average Pump powers as low as 25 mW (at a repetition rate of 75 MHz) have been used for terahertz generation. This and the general performance make the spintronic terahertz emitter compatible with established emitters based on nonlinear generation methods.
Franz X. Kärtner - One of the best experts on this subject based on the ideXlab platform.
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high energy phase stable ultrabroadband khz opcpa at 2 1 μm Pumped by a picosecond cryogenic yb yag Laser
Optics Express, 2011Co-Authors: Kyunghan Hong, Phillip D Keathley, Jeffrey Moses, Shuwei Huang, Chienjen Lai, Giovanni Cirmi, Alexander Sell, Eduardo Granados, Franz X. KärtnerAbstract:We report on a kHz, mJ-level, carrier-envelope phase (CEP)-stable ultrabroadband optical parametric chirped-pulse amplifier (OPCPA) at 2.1-μm wavelength, Pumped by a high-energy, 14 ps, cryogenic Yb:YAG Pump Laser, and its application to high-order harmonic generation (HHG) with Xe. The pre-amplifier chain is Pumped by a 12-ps Nd:YLF Pump Laser and both Pump Lasers are optically synchronized to the signal pulse of the OPCPA. An amplified pulse energy of 0.85 mJ was obtained at the final OPCPA stage with good beam profile. The pulse is compressed to 4.5 optical cycles ( 85 eV with an efficiency of ~10-10 per harmonic, limited by the maximum gas pressure and flow into the chamber. This demonstrates the potential of this 2.1-μm source for scaling of photon energy and flux in the water-window range when applied to Ne and He at kHz repetition rate.
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performance scaling via passive pulse shaping in cavity enhanced optical parametric chirped pulse amplification
Optics Letters, 2010Co-Authors: Aleem Siddiqui, Jeffrey Moses, Kyunghan Hong, Franz X. KärtnerAbstract:We show that an enhancement cavity seeded at the full repetition rate of the Pump Laser can automatically reshape small-signal gain across the interacting pulses in an optical parametric chirped-pulse amplifier for close-to-optimal operation, significantly increasing both the gain bandwidth and the conversion efficiency, in addition to boosting gain for high-repetition-rate amplification. Applied to a degenerate amplifier, the technique can provide an octave-spanning gain bandwidth.
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diode Pumped mode locked nd glass Lasers with an antiresonant fabry perot saturable absorber
Optics Letters, 1995Co-Authors: Daniel Kopf, Uwe Keller, Franz X. Kärtner, K. J. WeingartenAbstract:We demonstrate passively mode-locked diode-Pumped Nd:glass Lasers with different media such as silicate, phosphate, and fluorophosphate that are homogeneously or inhomogeneously broadened. An antiresonant Fabry–Perot saturable absorber starts and stabilizes the soliton mode-locked Nd:glass Lasers, producing pulses as short as 130 fs at an average output power of 100 mW. With a cw Ti:sapphire Pump Laser we obtain pulses as short as 90 fs.
