The Experts below are selected from a list of 45231 Experts worldwide ranked by ideXlab platform

Takao Fuji - One of the best experts on this subject based on the ideXlab platform.

  • phase stable sub cycle mid infrared conical emission from filamentation in gases
    Optics Express, 2012
    Co-Authors: Yutaka Nomura, Hideto Shirai, Kenta Ishii, Noriaki Tsurumachi, Alexander A Voronin, A M Zheltikov, Takao Fuji
    Abstract:

    Sub-single-cycle pulses in the mid-infrared (MIR) region were generated through a conical emission from a laser-induced filament. Fundamental and second-harmonic pulses of 25-fs Ti:sapphire Amplifier Output were focused into argon to produce phase-stable broadband MIR pulses in a well-focusable ring-shaped beam. The beam profile and spectrum of the MIR field are accurately reproduced with a simple calculation based on a four-wave mixing process. The ring-shaped pattern of the MIR beam originates from a dramatic confocal-parameter mismatch between the MIR field and the laser beams.

  • generation of sub two cycle mid infrared pulses by four wave mixing through filamentation in air
    Optics Letters, 2007
    Co-Authors: Takao Fuji, Toshinori Suzuki
    Abstract:

    Generation of sub-two-cycle, microjoule pulses in the mid-infrared region is demonstrated. Fundamental and second-harmonic pulses of 25 fs Ti:sapphire Amplifier Output were focused into the air to produce extremely broadband mid-infrared pulses by four-wave difference-frequency generation through the filamentation. The full width at half-maximum of the spectral bandwidth reaches one octave (2.5-5.5 μm), which is sufficiently broad for sub-single-cycle pulse generation. The pulse width was estimated to be 13 fs, without any compressors, by cross-correlation frequency resolved optical gating. The Output energy of more than a few microjoule is sufficient for spectroscopy.

  • generation of 12 fs deep ultraviolet pulses by four wave mixing through filamentation in neon gas
    Optics Letters, 2007
    Co-Authors: Takao Fuji, Takuya Horio, Toshinori Suzuki
    Abstract:

    Generation of deep-ultraviolet femtosecond pulses by four-wave mixing through filamentation in neon gas was demonstrated. Fundamental (ω) and second-harmonic (2ω) pulses of 25 fs Ti:sapphire Amplifier Output were focused into neon gas, and 20 μJ pulses with the center wavelength of 260 nm were produced by a four-wave mixing process, 2ω+2ω−ω→3ω through an ∼15 cm filament. Additionally, pulses with an energy of 2 μJ at 200 nm were generated, probably by a cascaded process, 3ω+2ω−ω→4ω. The 260 nm pulses were compressed by a grating-based compressor and characterized by a dispersion-free transient grating frequency-resolved optical gating. The estimated pulse width was 12 fs.

Johann W Kolar - One of the best experts on this subject based on the ideXlab platform.

  • novel tracking power supply for linear power Amplifiers
    IEEE Transactions on Industrial Electronics, 2008
    Co-Authors: G Gong, H Ertl, Johann W Kolar
    Abstract:

    Conventional linear power Amplifiers (LPAs) show a high Output voltage quality but are characterized by high power losses and/or low power density. Therefore, there is a growing interest in increasing the efficiency of LPAs, e.g., for the realization of high power testing voltage sources. In this paper, a high-frequency isolated boost-type tracking power supply (TPS) system is proposed for the conditioning of the input voltage of an LPA. The Output voltage of the TPS is varied according to the voltage to be formed by the LPA so that the voltage drop across the power Amplifier Output transistors is reduced to low values. This results in a significant increase of the total system efficiency. The operating principle of the proposed system is described. A design method for the Output filter using the power supply rejection ratio of the LPA is proposed. This method ensures that the Amplifier Output voltage has minimal switching frequency components. Furthermore, a control system design method is presented that ensures good performance in the control of the constant inductor current of the switch-mode tracking stage. Finally, the theoretical considerations are verified by measurements on a 1-kW laboratory prototype.

  • design control and performance of tracking power supply for a linear power Amplifier
    Power Electronics Specialists Conference, 2005
    Co-Authors: G Gong, S D Round, Johann W Kolar
    Abstract:

    Power Amplifiers are widely used in consumer and industrial applications and are based on either a linear power Amplifier or switch-mode power Amplifier design. By combining the linear power Amplifier with a switch-mode tracking power supply, a hybrid power Amplifier is formed that maintains a high quality Output while having a high efficiency. This paper presents a hybrid Amplifier that is constructed with a novel boost-type tracking power supply and provides an excellent performance. A design method for the Output filter using the power supply ratio rejection (PSRR) of the linear power Amplifier is proposed. This method ensures that the Amplifier Output voltage has minimal switching frequency components as well as being able to quickly track changes in the Output voltage. A control system design method is presented that ensures good performance in the control of the constant inductor current of the switch-mode tracking stage and a high rejection of Output voltage disturbances. A laboratory prototype experimentally verifies the theoretical analysis

Toshinori Suzuki - One of the best experts on this subject based on the ideXlab platform.

  • generation of sub two cycle mid infrared pulses by four wave mixing through filamentation in air
    Optics Letters, 2007
    Co-Authors: Takao Fuji, Toshinori Suzuki
    Abstract:

    Generation of sub-two-cycle, microjoule pulses in the mid-infrared region is demonstrated. Fundamental and second-harmonic pulses of 25 fs Ti:sapphire Amplifier Output were focused into the air to produce extremely broadband mid-infrared pulses by four-wave difference-frequency generation through the filamentation. The full width at half-maximum of the spectral bandwidth reaches one octave (2.5-5.5 μm), which is sufficiently broad for sub-single-cycle pulse generation. The pulse width was estimated to be 13 fs, without any compressors, by cross-correlation frequency resolved optical gating. The Output energy of more than a few microjoule is sufficient for spectroscopy.

  • generation of 12 fs deep ultraviolet pulses by four wave mixing through filamentation in neon gas
    Optics Letters, 2007
    Co-Authors: Takao Fuji, Takuya Horio, Toshinori Suzuki
    Abstract:

    Generation of deep-ultraviolet femtosecond pulses by four-wave mixing through filamentation in neon gas was demonstrated. Fundamental (ω) and second-harmonic (2ω) pulses of 25 fs Ti:sapphire Amplifier Output were focused into neon gas, and 20 μJ pulses with the center wavelength of 260 nm were produced by a four-wave mixing process, 2ω+2ω−ω→3ω through an ∼15 cm filament. Additionally, pulses with an energy of 2 μJ at 200 nm were generated, probably by a cascaded process, 3ω+2ω−ω→4ω. The 260 nm pulses were compressed by a grating-based compressor and characterized by a dispersion-free transient grating frequency-resolved optical gating. The estimated pulse width was 12 fs.

Nasse Peyghambaria - One of the best experts on this subject based on the ideXlab platform.

  • high power narrow linewidth continuous wave raman Amplifier at 1 27 mu m
    IEEE Photonics Technology Letters, 2011
    Co-Authors: J Nagel, Evgeny M Dianov, Valery L Temyanko, Jeremy Doble, A S Iriukov, A A Sysoliati, Robe A Norwood, Nasse Peyghambaria
    Abstract:

    A high-power narrow-linewidth continuous-wave (CW) Raman fiber Amplifier at 1.27 μm is demonstrated for remote sensing measurements of atmospheric oxygen (O2). The Amplifier uses phosphosilicate fiber in both a standard single-mode design and with the core size varying in the longitudinal direction for stimulated Brillouin scattering (SBS) suppression. The highest reported power level at this wavelength to date, a total peak power of 3 W, has been achieved for online (2.4 W) and offline (580 mW) spectroscopic measurements, in agreement with theoretical predictions. Additionally, it is shown that when 60-kHz sinusoidal amplitude modulation is applied to the Amplifier seed signal, the modulated wave form is preserved at the Amplifier Output with 1.8 W total average power being obtained.

G Gong - One of the best experts on this subject based on the ideXlab platform.

  • novel tracking power supply for linear power Amplifiers
    IEEE Transactions on Industrial Electronics, 2008
    Co-Authors: G Gong, H Ertl, Johann W Kolar
    Abstract:

    Conventional linear power Amplifiers (LPAs) show a high Output voltage quality but are characterized by high power losses and/or low power density. Therefore, there is a growing interest in increasing the efficiency of LPAs, e.g., for the realization of high power testing voltage sources. In this paper, a high-frequency isolated boost-type tracking power supply (TPS) system is proposed for the conditioning of the input voltage of an LPA. The Output voltage of the TPS is varied according to the voltage to be formed by the LPA so that the voltage drop across the power Amplifier Output transistors is reduced to low values. This results in a significant increase of the total system efficiency. The operating principle of the proposed system is described. A design method for the Output filter using the power supply rejection ratio of the LPA is proposed. This method ensures that the Amplifier Output voltage has minimal switching frequency components. Furthermore, a control system design method is presented that ensures good performance in the control of the constant inductor current of the switch-mode tracking stage. Finally, the theoretical considerations are verified by measurements on a 1-kW laboratory prototype.

  • design control and performance of tracking power supply for a linear power Amplifier
    Power Electronics Specialists Conference, 2005
    Co-Authors: G Gong, S D Round, Johann W Kolar
    Abstract:

    Power Amplifiers are widely used in consumer and industrial applications and are based on either a linear power Amplifier or switch-mode power Amplifier design. By combining the linear power Amplifier with a switch-mode tracking power supply, a hybrid power Amplifier is formed that maintains a high quality Output while having a high efficiency. This paper presents a hybrid Amplifier that is constructed with a novel boost-type tracking power supply and provides an excellent performance. A design method for the Output filter using the power supply ratio rejection (PSRR) of the linear power Amplifier is proposed. This method ensures that the Amplifier Output voltage has minimal switching frequency components as well as being able to quickly track changes in the Output voltage. A control system design method is presented that ensures good performance in the control of the constant inductor current of the switch-mode tracking stage and a high rejection of Output voltage disturbances. A laboratory prototype experimentally verifies the theoretical analysis