The Experts below are selected from a list of 208644 Experts worldwide ranked by ideXlab platform

Hiromasa Ito - One of the best experts on this subject based on the ideXlab platform.

  • surface emitted terahertz wave difference Frequency Generation in periodically poled lithium niobate ridge type waveguide
    Japanese Journal of Applied Physics, 2006
    Co-Authors: Y Sasaki, Hiromasa Ito, Koji Suizu, Yusaku Suzuki, Shoichiro Yamaguchi, Minoru Imaeda
    Abstract:

    We demonstrated surface-emitted terahertz (THz)-wave difference-Frequency Generation from a periodically poled magnesium-oxide-doped lithium niobate (PPMgLN) ridge-type optical waveguide. The periodic structure in the direction of propagation of the incident laser light was sufficient for surface emission because the incident laser light was confined within a waveguide. Tunable THz waves were generated at around 1 and 1.5 THz using two ridge-type PPMgLN waveguides. The generated THz wavelengths were determined under the quasi-phase matching condition.

  • surface emitted terahertz wave difference Frequency Generation in two dimensional periodically poled lithium niobate
    Optics Letters, 2005
    Co-Authors: Y Sasaki, Yuri Avetisyan, Hiroyuki Yokoyama, Hiromasa Ito
    Abstract:

    We report on the demonstration of surface-emitted terahertz- (THz-) wave difference-Frequency Generation from two-dimensional (2D) periodically poled lithium niobate (PPLN). The two orthogonal periodic structures individually compensate for both the phase mismatch of the launched lasers and the generated THz wave. Tunable 1.5–1.8 THz wave Generation with a bandwidth of 10-GHz was obtained by use of two 2D PPLN crystals. We also confirmed that THz waves were simultaneously generated into two opposite directions, which suggests the possibility of higher THz-wave output power.

  • terahertz wave surface emitted difference Frequency Generation in slant stripe type periodically poled linbo3 crystal
    Applied Physics Letters, 2002
    Co-Authors: Y Sasaki, Kodo Kawase, Avetisyan Yuri, Hiromasa Ito
    Abstract:

    We demonstrate terahertz-wave (THz-wave) surface-emitted difference Frequency Generation with nanosecond pulse duration. A slant-stripe-type periodically poled lithium niobate (PPLN) crystal was used to realize the quasi-phase-matching in two mutually perpendicular directions of optical and THz-wave propagation. A THz-wave with a wavelength near 200 μm was generated by mixing the radiation of a dual-signal-wave optical parametric oscillator based on a periodically phase-reversed PPLN crystal.

  • thz wave surface emitted difference Frequency Generation in nonlinear materials
    Applied and Environmental Microbiology, 2000
    Co-Authors: Yuri Avetisyan, Kodo Kawase, Hiromasa Ito
    Abstract:

    Summary form only given. The nonlinear difference-Frequency mixing between two laser sources is widely used method of coherent THz-wave Generation. Unfortunately many nonlinear materials have a large absorption in THz region. To overcoming this problem we offer to realize difference Frequency Generation (DFG) in surface emitting geometry (SEG). In contrast to collinear geometry, the thickness of nonlinear optical waveguide, which is usually much less than its length determine the absorption of emitted wave in SEG. The additional advantage of SEG is a significant increase of Generation efficiency due to the possibility of application of resonant cavities both at a pumping and at a difference Frequency. The SEG allows the separate optimization of both optical and THz cavities. We have proposed a new simple method of THz-wave Generation in the strongly absorbing material based on the surface-emitted DFG.

Mikhail A Belkin - One of the best experts on this subject based on the ideXlab platform.

  • terahertz sources based on cerenkov difference Frequency Generation in quantum cascade lasers
    Applied Physics Letters, 2012
    Co-Authors: Karun Vijayraghavan, R W Adams, Augustinas Vizbaras, Min Jang, Christian Grasse, Gerhard Boehm, Markus C Amann, Mikhail A Belkin
    Abstract:

    We report room-temperature terahertz sources based on Cerenkov difference-Frequency Generation in dual-wavelength mid-infrared quantum cascade lasers with giant resonant optical nonlinearities originating from intersubband transitions. A Cerenkov difference-Frequency Generation scheme allows for extraction of THz radiation along the whole length of the laser waveguide and provides directional terahertz emission. Experimentally, our sources demonstrate a conversion efficiency of up to 70 μW/W2 approximately an order of magnitude improvement over the previous reports.

  • room temperature terahertz quantum cascade laser source based on intracavity difference Frequency Generation
    Applied Physics Letters, 2008
    Co-Authors: Mikhail A Belkin, Alexey Belyanin, Federico Capasso, Feng Xie, M Fischer, Andreas Wittmann, Jerome Faist
    Abstract:

    We report on our progress in the development of a terahertz quantum cascade laser source based on intracavity terahertz difference-Frequency mixing in a dual-wavelength mid-infrared quantum cascade laser with the active region engineered to possess giant second-order nonlinear susceptibility. In this letter, we demonstrate devices that operate in mid-infrared at λ1=8.9μm and λ2=10.5μm and produce terahertz output at λ≈60μm via difference-Frequency Generation with 7μW output power at 80K, 1μW output at 250K, and still approximately 300nW output at 300K.

  • terahertz quantum cascade laser source based on intracavity difference Frequency Generation
    Nature Photonics, 2007
    Co-Authors: Mikhail A Belkin, Alexey Belyanin, Federico Capasso, Deborah L Sivco, A Y Cho, D C Oakley, C J Vineis, G W Turner
    Abstract:

    The terahertz spectral range (λ = 30–300 µm) has long been devoid of compact, electrically pumped, room-temperature semiconductor sources1,2,3,4. Despite recent progress with terahertz quantum cascade lasers2,3,4, existing devices still require cryogenic cooling. An alternative way to produce terahertz radiation is Frequency down-conversion in a nonlinear optical crystal using infrared or visible pump lasers5,6,7. This approach offers broad spectral tunability and does work at room temperature; however, it requires powerful laser pumps and a more complicated optical set-up, resulting in bulky and unwieldy sources. Here we demonstrate a monolithically integrated device designed to combine the advantages of electrically pumped semiconductor lasers and nonlinear optical sources. Our device is a dual-wavelength quantum cascade laser8 with the active region engineered to possess giant second-order nonlinear susceptibility associated with intersubband transitions in coupled quantum wells. The laser operates at λ1 = 7.6 µm and λ2 = 8.7 µm, and produces terahertz output at λ = 60 µm through intracavity difference-Frequency Generation.

Yuri Avetisyan - One of the best experts on this subject based on the ideXlab platform.

  • terahertz wave surface emitted difference Frequency Generation without quasi phase matching technique
    Optics Letters, 2010
    Co-Authors: Yuri Avetisyan
    Abstract:

    A scheme of terahertz (THz)-wave surface-emitted difference-Frequency Generation (SEDFG), which lacks the drawbacks associated with the usage of periodically orientation-inverted structures, is proposed. It is shown that both material birefringence of the bulk LiNbO3 crystal and modal birefringence of GaAs/AlAs waveguide are sufficient to obtain SEDFG up to a Frequency of ~3THz. The simplicity of the proposed scheme, along with the fact that there is a much smaller THz-wave decay in nonlinear crystal, makes it a good candidate for the practical realization of efficient THz Generation. The use of a GaAs waveguide with an oxidized AlAs layer is proposed for enhanced THz-wave SEDFG in the vicinity of the GaAs polariton resonance at 8THz.

  • surface emitted terahertz wave difference Frequency Generation in two dimensional periodically poled lithium niobate
    Optics Letters, 2005
    Co-Authors: Y Sasaki, Yuri Avetisyan, Hiroyuki Yokoyama, Hiromasa Ito
    Abstract:

    We report on the demonstration of surface-emitted terahertz- (THz-) wave difference-Frequency Generation from two-dimensional (2D) periodically poled lithium niobate (PPLN). The two orthogonal periodic structures individually compensate for both the phase mismatch of the launched lasers and the generated THz wave. Tunable 1.5–1.8 THz wave Generation with a bandwidth of 10-GHz was obtained by use of two 2D PPLN crystals. We also confirmed that THz waves were simultaneously generated into two opposite directions, which suggests the possibility of higher THz-wave output power.

  • thz wave surface emitted difference Frequency Generation in nonlinear materials
    Applied and Environmental Microbiology, 2000
    Co-Authors: Yuri Avetisyan, Kodo Kawase, Hiromasa Ito
    Abstract:

    Summary form only given. The nonlinear difference-Frequency mixing between two laser sources is widely used method of coherent THz-wave Generation. Unfortunately many nonlinear materials have a large absorption in THz region. To overcoming this problem we offer to realize difference Frequency Generation (DFG) in surface emitting geometry (SEG). In contrast to collinear geometry, the thickness of nonlinear optical waveguide, which is usually much less than its length determine the absorption of emitted wave in SEG. The additional advantage of SEG is a significant increase of Generation efficiency due to the possibility of application of resonant cavities both at a pumping and at a difference Frequency. The SEG allows the separate optimization of both optical and THz cavities. We have proposed a new simple method of THz-wave Generation in the strongly absorbing material based on the surface-emitted DFG.

Kodo Kawase - One of the best experts on this subject based on the ideXlab platform.

  • cherenkov phase matched monochromatic thzwave Generation using difference Frequency Generation with a lithium niobate crystal
    Optics Express, 2008
    Co-Authors: Koji Suizu, Takayuki Shibuya, Takuya Akiba, Toshihiro Tutui, Chiko Otani, Kodo Kawase
    Abstract:

    We demonstrated a Cherenkov phase-matching method for monochromatic THz-wave Generation using the difference Frequency Generation process with a lithium niobate crystal, which resulted in high conversion efficiency and wide tunability. We successfully generated monochromatic THz waves across the range 0.2–3.0 THz. We obtained efficient energy conversion in the low Frequency region below 0.5 THz, and achieved a flat tuning spectrum by varying the pumping wavelength during THz-wave tuning.

  • cherenkov phase matched monochromatic thz wave Generation using difference Frequency Generation with a lithium niobate crystal
    Optics Express, 2008
    Co-Authors: Koji Suizu, Takayuki Shibuya, Takuya Akiba, Toshihiro Tutui, Chiko Otani, Kodo Kawase
    Abstract:

    We demonstrated a Cherenkov phase-matching method for monochromatic THz-wave Generation using the difference Frequency Generation process with a lithium niobate crystal, which resulted in high conversion efficiency and wide tunability. We successfully generated monochromatic THz waves across the range 0.2–3.0 THz. We obtained efficient energy conversion in the low Frequency region below 0.5 THz, and achieved a flat tuning spectrum by varying the pumping wavelength during THz-wave tuning.

  • terahertz wave surface emitted difference Frequency Generation in slant stripe type periodically poled linbo3 crystal
    Applied Physics Letters, 2002
    Co-Authors: Y Sasaki, Kodo Kawase, Avetisyan Yuri, Hiromasa Ito
    Abstract:

    We demonstrate terahertz-wave (THz-wave) surface-emitted difference Frequency Generation with nanosecond pulse duration. A slant-stripe-type periodically poled lithium niobate (PPLN) crystal was used to realize the quasi-phase-matching in two mutually perpendicular directions of optical and THz-wave propagation. A THz-wave with a wavelength near 200 μm was generated by mixing the radiation of a dual-signal-wave optical parametric oscillator based on a periodically phase-reversed PPLN crystal.

  • thz wave surface emitted difference Frequency Generation in nonlinear materials
    Applied and Environmental Microbiology, 2000
    Co-Authors: Yuri Avetisyan, Kodo Kawase, Hiromasa Ito
    Abstract:

    Summary form only given. The nonlinear difference-Frequency mixing between two laser sources is widely used method of coherent THz-wave Generation. Unfortunately many nonlinear materials have a large absorption in THz region. To overcoming this problem we offer to realize difference Frequency Generation (DFG) in surface emitting geometry (SEG). In contrast to collinear geometry, the thickness of nonlinear optical waveguide, which is usually much less than its length determine the absorption of emitted wave in SEG. The additional advantage of SEG is a significant increase of Generation efficiency due to the possibility of application of resonant cavities both at a pumping and at a difference Frequency. The SEG allows the separate optimization of both optical and THz cavities. We have proposed a new simple method of THz-wave Generation in the strongly absorbing material based on the surface-emitted DFG.

Ruidan Zhang - One of the best experts on this subject based on the ideXlab platform.

  • flexible high resolution broadband sum Frequency Generation vibrational spectroscopy for intrinsic spectral line widths
    Journal of Chemical Physics, 2019
    Co-Authors: Ruidan Zhang, Xingxing Peng, Zhirun Jiao, Ting Luo, Chuanyao Zhou, Xueming Yang
    Abstract:

    The difficulty in achieving high spectral resolution and accurate line shape in sum-Frequency Generation vibrational spectroscopy (SFG-VS) has restricted its use in applications requiring precise detection and quantitative analysis. Recently, the development of high-resolution broadband sum-Frequency Generation vibrational spectroscopy (HR-BB-SFG-VS) with sub-wavenumber resolution generated by synchronizing two independent amplifier lasers have opened new opportunities for probing an intrinsic SFG response. Here, we present a new flexible approach to achieve HR-BB-SFG-VS. In this system, two reGeneration amplifiers shared the same oscillator laser as the seed, and a time-asymmetric visible pulse with a nearly Lorentzian line shape filtered by an etalon was used to overlap with a femtosecond broadband infrared pulse. This Lorentzian line shape of the visible pulse can greatly simplify the spectral fitting and analysis. We also demonstrated that the single-sided long visible pulse provided both high spectral resolution (1.4 cm-1) and effective suppression of the non-resonant background by detuning the time delay between visible and infrared pulses in SFG-VS measurements. With this new SFG setup, a pair of spectral splittings by 3.1 ± 0.7 and 3 ± 0.2 cm-1 for the symmetric and antisymmetric stretching of the CH3 group was resolved at the CH3CN/TiO2(110) surface, which are tentatively attributed to two different orientational methyl groups. These technological advancements can help broaden the applications of HR-BB-SFG-VS and provide solid ground for a better understanding of complex molecular structures and dynamics at interfaces.