The Experts below are selected from a list of 56976 Experts worldwide ranked by ideXlab platform

Shinichi Takagi - One of the best experts on this subject based on the ideXlab platform.

  • low parasitic capacitance iii v si hybrid mos optical modulator toward high speed Modulation
    Optical Fiber Communication Conference, 2020
    Co-Authors: Junichi Fujikata, Shinichi Takagi, Masataka Noguchi, Shigeki Takahashi, Kasidit Toprasertpong, Mitsuru Takenaka
    Abstract:

    We present advanced design of III-V/Si hybrid MOS optical modulator to reduce parasitic capacitance and resistance toward high-speed Modulation. We successfully achieved 21 times smaller RC constant, improving the trade-off between Modulation Efficiency and bandwidth.

  • efficient low loss ingaasp si hybrid mos optical modulator
    Nature Photonics, 2017
    Co-Authors: Shinichi Takagi, Junichi Fujikata, Shigeki Takahashi, Jaehoon Han, F Boeuf, Mitsuru Takenaka
    Abstract:

    Hybrid InGaAsP/Si optical modulator gives silicon photonics an efficient scheme for phase Modulation. An optical modulator integrated on silicon is a key enabler for high-performance optical interconnects1,2,3,4,5,6. However, Si-based optical modulators suffer from low phase-Modulation Efficiency owing to the weak plasma dispersion effect in Si, which also results in large optical loss. Therefore, it is essential to find a novel Modulation scheme for Si photonics. Here, we demonstrate an InGaAsP/Si hybrid metal-oxide–semiconductor (MOS) optical modulator formed by direct wafer bonding7,8. Electron accumulation at the InGaAsP MOS interface enables the utilization of the electron-induced refractive index change in InGaAsP, which is significantly greater than that in Si (refs 9,10). The presented modulator exhibits a phase-Modulation Efficiency of 0.047 Vcm and low optical attenuation of 0.23 dB at π phase shift at 1.55 μm wavelength, which are approximately 5 times higher and 10 times lower than Si MOS optical modulators11,12,13,14,15,16,17, respectively. This approach provides a new, high-performance phase-Modulation scheme for Si photonics.

  • extremely high Modulation Efficiency iu v si hybrid mos optical modulator fabricated by direct wafer bonding
    International Electron Devices Meeting, 2016
    Co-Authors: Jaehoon Han, Mitsuru Takenaka, Shinichi Takagi
    Abstract:

    We have demonstrated an optical modulator with an InGaAsP/Si hybrid MOS-based phase shifter on Si photonics platform by using direct wafer bonding. Since the electron-induced refractive index change in InGaAsP is much greater than Si, electron accumulation at the InGaAsP MOS interface enables an extremely high Modulation Efficiency. In conjunction with the void-free direct wafer bonding with ALD Al 2 O 3 bonding interface, we have achieved the superior InGaAsP/Al 2 O 3 /Si hybrid MOS interface. Thus, we have successfully fabricated the InGaAsP/Si hybrid MOS optical modulator, exhibiting a Modulation Efficiency V π L of 0.047 Vcm, approximately 5 times better than that of Si-based MOS optical modulators reported so far even with a similar EOT of 5 nm. Thus, the heterogeneous integration of InGaAsP on Si is effective for significantly improving performance of MOS optical modulators through breaking the inherent trade-off between the EOT scaling and Modulation bandwidth.

  • strain induced enhancement of plasma dispersion effect and free carrier absorption in sige optical modulators
    Scientific Reports, 2015
    Co-Authors: Mitsuru Takenaka, Takenori Osada, Masahiko Hata, Shinichi Takagi
    Abstract:

    The plasma dispersion effect and free-carrier absorption are widely used to change refractive index and absorption coefficient in Si-based optical modulators. However, the weak free-carrier effects in Si cause low Modulation Efficiency, resulting in large device footprint and power consumption. Here, we theoretically and experimentally investigate the enhancement of the free-carrier effects by strain-induced mass Modulation in silicon-germanium (SiGe). The application of compressive strain to SiGe reduces the conductivity effective mass of holes, resulting in the enhanced free-carrier effects. Thus, the strained SiGe-based optical modulator exhibits more than twice Modulation Efficiency as large as that of the Si modulator. To the best of our knowledge, this is the first demonstration of the enhanced free-carrier effects in strained SiGe at the near-infrared telecommunication wavelength. The strain-induced enhancement technology for the free-carrier effects is expected to boost Modulation Efficiency of the most Si-based optical modulators thanks to high complementary metal-oxide-semiconductor (CMOS) compatibility.

  • strain induced enhancement of plasma dispersion effect and free carrier absorption in sige optical modulators
    arXiv: Optics, 2013
    Co-Authors: Mitsuru Takenaka, Takenori Osada, Masahiko Hata, Shinichi Takagi
    Abstract:

    The plasma dispersion effect and free-carrier absorption are widely used for changing refractive index and absorption coefficient in Si-based optical modulators. However, these free-carrier effects in Si are not large enough for making the footprint of the Si modulators small. Here, we have theoretically and experimentally investigated the enhancement of the plasma dispersion effect and free-carrier absorption by strain-induced mass Modulation in silicon-germanium (SiGe). The application of compressive strain to SiGe reduces the conductivity hole mass, resulting in the enhanced free-carrier effects. Thus, the strained SiGe-based optical modulator exhibits more than twice Modulation Efficiency as large as that of the Si modulator. To the best of our knowledge, it is the first demonstration of the enhanced free-carrier effects in strained SiGe at the near-infrared telecommunication wavelength. The strain-induced enhancement technology for the free-carrier effects is expected to boost the Modulation Efficiency of the most Si-based optical modulators thanks to high complementary metal-oxide-semiconductor (CMOS) compatibility.

John E Bowers - One of the best experts on this subject based on the ideXlab platform.

  • 50 gb s hybrid silicon traveling wave electroabsorption modulator
    Optics Express, 2011
    Co-Authors: Yongbo Tang, Huiwen Chen, Siddharth R Jain, Jonathan D Peters, Urban Westergren, John E Bowers
    Abstract:

    We have demonstrated a traveling-wave electroabsorption modulator based on the hybrid silicon platform. For a device with a 100 μm active segment, the small-signal electro/optical response renders a 3 dB bandwidth of around 42 GHz and its Modulation Efficiency reaches 23 GHz/V. A dynamic extinction ratio of 9.8 dB with a driving voltage swing of only 2 V was demonstrated at a transmission rate of 50 Gb/s. This represents a significant improvement for modulators compatible with integration of silicon-based photonic integrated circuits.

  • high extinction ratio and saturation power traveling wave electroabsorption modulator
    IEEE Photonics Technology Letters, 2002
    Co-Authors: Yijen Chiu, P Abraham, Hsufeng Chou, V Kaman, John E Bowers
    Abstract:

    An InGaAsP multiquantum-well traveling-wave electroabsorption modulator is demonstrated with high extinction ratio and Modulation Efficiency. By designing a strain-compensated quantum-well active region with traveling-wave design, high saturation power (>14 dBm) for >20-GHz high-speed performance (1.5 dB drop at 20 GHz) is achieved. Due to high Modulation Efficiency (>30 dBN for 0 to 1 V 40-dB extinction ratio in 2 V), error free 10-Gb/s operation with 1 V/sub p-p/ driving voltage is obtained. By comparing codirections and counterdirections of optical and microwave interactions, pulse generation at 40 GHz shows that the traveling-wave performance has an advantage for short pulses with high-power output, where pulsewidth as short as 4.5 ps is obtained in this kind of device.

Mitsuru Takenaka - One of the best experts on this subject based on the ideXlab platform.

  • low parasitic capacitance iii v si hybrid mos optical modulator toward high speed Modulation
    Optical Fiber Communication Conference, 2020
    Co-Authors: Junichi Fujikata, Shinichi Takagi, Masataka Noguchi, Shigeki Takahashi, Kasidit Toprasertpong, Mitsuru Takenaka
    Abstract:

    We present advanced design of III-V/Si hybrid MOS optical modulator to reduce parasitic capacitance and resistance toward high-speed Modulation. We successfully achieved 21 times smaller RC constant, improving the trade-off between Modulation Efficiency and bandwidth.

  • efficient low loss ingaasp si hybrid mos optical modulator
    Nature Photonics, 2017
    Co-Authors: Shinichi Takagi, Junichi Fujikata, Shigeki Takahashi, Jaehoon Han, F Boeuf, Mitsuru Takenaka
    Abstract:

    Hybrid InGaAsP/Si optical modulator gives silicon photonics an efficient scheme for phase Modulation. An optical modulator integrated on silicon is a key enabler for high-performance optical interconnects1,2,3,4,5,6. However, Si-based optical modulators suffer from low phase-Modulation Efficiency owing to the weak plasma dispersion effect in Si, which also results in large optical loss. Therefore, it is essential to find a novel Modulation scheme for Si photonics. Here, we demonstrate an InGaAsP/Si hybrid metal-oxide–semiconductor (MOS) optical modulator formed by direct wafer bonding7,8. Electron accumulation at the InGaAsP MOS interface enables the utilization of the electron-induced refractive index change in InGaAsP, which is significantly greater than that in Si (refs 9,10). The presented modulator exhibits a phase-Modulation Efficiency of 0.047 Vcm and low optical attenuation of 0.23 dB at π phase shift at 1.55 μm wavelength, which are approximately 5 times higher and 10 times lower than Si MOS optical modulators11,12,13,14,15,16,17, respectively. This approach provides a new, high-performance phase-Modulation scheme for Si photonics.

  • extremely high Modulation Efficiency iu v si hybrid mos optical modulator fabricated by direct wafer bonding
    International Electron Devices Meeting, 2016
    Co-Authors: Jaehoon Han, Mitsuru Takenaka, Shinichi Takagi
    Abstract:

    We have demonstrated an optical modulator with an InGaAsP/Si hybrid MOS-based phase shifter on Si photonics platform by using direct wafer bonding. Since the electron-induced refractive index change in InGaAsP is much greater than Si, electron accumulation at the InGaAsP MOS interface enables an extremely high Modulation Efficiency. In conjunction with the void-free direct wafer bonding with ALD Al 2 O 3 bonding interface, we have achieved the superior InGaAsP/Al 2 O 3 /Si hybrid MOS interface. Thus, we have successfully fabricated the InGaAsP/Si hybrid MOS optical modulator, exhibiting a Modulation Efficiency V π L of 0.047 Vcm, approximately 5 times better than that of Si-based MOS optical modulators reported so far even with a similar EOT of 5 nm. Thus, the heterogeneous integration of InGaAsP on Si is effective for significantly improving performance of MOS optical modulators through breaking the inherent trade-off between the EOT scaling and Modulation bandwidth.

  • strain induced enhancement of plasma dispersion effect and free carrier absorption in sige optical modulators
    Scientific Reports, 2015
    Co-Authors: Mitsuru Takenaka, Takenori Osada, Masahiko Hata, Shinichi Takagi
    Abstract:

    The plasma dispersion effect and free-carrier absorption are widely used to change refractive index and absorption coefficient in Si-based optical modulators. However, the weak free-carrier effects in Si cause low Modulation Efficiency, resulting in large device footprint and power consumption. Here, we theoretically and experimentally investigate the enhancement of the free-carrier effects by strain-induced mass Modulation in silicon-germanium (SiGe). The application of compressive strain to SiGe reduces the conductivity effective mass of holes, resulting in the enhanced free-carrier effects. Thus, the strained SiGe-based optical modulator exhibits more than twice Modulation Efficiency as large as that of the Si modulator. To the best of our knowledge, this is the first demonstration of the enhanced free-carrier effects in strained SiGe at the near-infrared telecommunication wavelength. The strain-induced enhancement technology for the free-carrier effects is expected to boost Modulation Efficiency of the most Si-based optical modulators thanks to high complementary metal-oxide-semiconductor (CMOS) compatibility.

  • strain induced enhancement of plasma dispersion effect and free carrier absorption in sige optical modulators
    arXiv: Optics, 2013
    Co-Authors: Mitsuru Takenaka, Takenori Osada, Masahiko Hata, Shinichi Takagi
    Abstract:

    The plasma dispersion effect and free-carrier absorption are widely used for changing refractive index and absorption coefficient in Si-based optical modulators. However, these free-carrier effects in Si are not large enough for making the footprint of the Si modulators small. Here, we have theoretically and experimentally investigated the enhancement of the plasma dispersion effect and free-carrier absorption by strain-induced mass Modulation in silicon-germanium (SiGe). The application of compressive strain to SiGe reduces the conductivity hole mass, resulting in the enhanced free-carrier effects. Thus, the strained SiGe-based optical modulator exhibits more than twice Modulation Efficiency as large as that of the Si modulator. To the best of our knowledge, it is the first demonstration of the enhanced free-carrier effects in strained SiGe at the near-infrared telecommunication wavelength. The strain-induced enhancement technology for the free-carrier effects is expected to boost the Modulation Efficiency of the most Si-based optical modulators thanks to high complementary metal-oxide-semiconductor (CMOS) compatibility.

Baohong Yuan - One of the best experts on this subject based on the ideXlab platform.

  • ultrasound modulated fluorescence based on a fluorophore quencher labeled microbubble system
    Journal of Biomedical Optics, 2009
    Co-Authors: Baohong Yuan
    Abstract:

    Ultrasound-modulated fluorescence from a fluorophore-quencher-labeled microbubble system driven by a single ultrasound pulse was theoretically quantified by solving a modified Herring equation (for bubble oscillation), a two-energy-level rate equation (for fluorophore excitation), and a diffusion equation (for light propagation in tissue). The Efficiency of quenching caused by fluorescence resonance energy transfer (FRET) between the fluorophore and the quencher was modulated when the microbubble oscillates in size driven by the ultrasound pulse. Both intensity- and lifetime-based imaging methods are discussed in three different illumination modes of the excitation light: continuous wave (DC), frequency domain (FD), and time domain (TD). Results show that microbubble expansion opens a time period during which the quenching Efficiency is dramatically reduced so that the emitted fluorescence strength and fluorophore lifetime are significantly increased. The Modulation Efficiency may even reach 100%. In addition, an important finding in this study is that in TD illumination mode, the modulated fluorescence photons may be temporally separated from the unmodulated photons, which makes the Modulation Efficiency limited only by thermal noise of the measurement system.

  • ultrasound modulated fluorescence based on a fluorophore quencher labeled microbubble system
    Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 2009
    Co-Authors: Baohong Yuan
    Abstract:

    Ultrasound-modulated fluorescence from a fluorophore-quencher labeled microbubble system driven by a single ultrasound pulse was theoretically quantified by solving a modified Herring equation (for bubble oscillation), a two-energy-level rate equation (for fluorophore excitation), and a diffusion equation (for light propagation in tissue). The Efficiency of quenching caused by fluorescence resonance energy transfer (FRET) between the fluorophore and the quencher was modulated when the microbubble oscillates in size driven by the ultrasound pulse. Both intensity- and lifetime-based imaging methods are discussed. An important finding in this study is that ultrasound-modulated fluorescent photons may be temporally separated from the un-modulated fluorescent photons if a super-short laser pulse is adopted. This result implies that the Modulation Efficiency may only be limited by thermal noise of the measurement system.

Shigehisa Arai - One of the best experts on this subject based on the ideXlab platform.

  • low bias current 10 gbit s direct Modulation of gainasp inp membrane dfb laser on silicon
    Optics Express, 2016
    Co-Authors: Daisuke Inoue, Takuo Hiratani, Kai Fukuda, Takahiro Tomiyasu, Tomohiro Amemiya, Nobuhiko Nishiyama, Shigehisa Arai
    Abstract:

    Low-power consumption directly-modulated lasers are a key device for on-chip optical interconnection. We fabricated a GaInAsP/InP membrane DFB laser that exhibited a low-threshold current of 0.21 mA and single-mode operation with a sub-mode suppression ratio of 47 dB at a bias current of 2 mA. A high Modulation Efficiency of 11 GHz/mA1/2 was obtained. A 10 Gbit/s direct Modulation using a non-return-to-zero 231-1 pseudo-random bit sequence signal was performed with a bias current of 1 mA, which is the lowest bias current ever reported for direct Modulation of a DFB laser. A bit-error rate of 10-9 was successfully achieved.

  • high Modulation Efficiency operation of gainasp inp membrane distributed feedback laser on si substrate
    Optics Express, 2015
    Co-Authors: Daisuke Inoue, Takuo Hiratani, Kai Fukuda, Takahiro Tomiyasu, Tomohiro Amemiya, Nobuhiko Nishiyama, Shigehisa Arai
    Abstract:

    The direct Modulation characteristics of a membrane distributed feedback (DFB) laser on a silicon substrate were investigated. Enhancement of the optical confinement factor in the membrane structure facilitates the fabrication of a strongly index-coupled (κ(I) = 1500 cm(-1)) DFB laser with the cavity length of 80 µm and a threshold current of 270 µA. Small-signal Modulation measurements yielded a -3dB bandwidth of 9.5 GHz at 1.03-mA bias current, with Modulation Efficiency of 9.9 GHz/mA(1/2), which is, to the best of our knowledge, the highest value among those reported for DFB lasers.