A5023393163- Photonic and Optical Devices
- Semiconductor Lasers and Optical Devices
- Optical Network Technologies
- Advanced Photonic Communication Systems
- Semiconductor materials and devices
- Ga2O3 and related materials
- ZnO doping and properties
- Advanced Memory and Neural Computing
- Neural Networks and Reservoir Computing
- Advanced Fiber Optic Sensors
- Photonic Crystals and Applications
- Semiconductor Quantum Structures and Devices
- Advanced Surface Polishing Techniques
- Perovskite Materials and Applications
- Optical Coatings and Gratings
- Photoreceptor and optogenetics research
- Nanowire Synthesis and Applications
- Electronic and Structural Properties of Oxides
- Silicon Nanostructures and Photoluminescence
- Molecular Junctions and Nanostructures
- Optical Coherence Tomography Applications
- Integrated Circuits and Semiconductor Failure Analysis
- Advancements in Semiconductor Devices and Circuit Design
- Advanced Photocatalysis Techniques
- Diamond and Carbon-based Materials Research
NTT (Japan)
2019-2024
Osaka City University
2015-2019
We investigate the photoluminescence (PL) dynamics of self-trapped excitons (STEs) in a $\ensuremath{\beta}\ensuremath{-}{\mathrm{Ga}}_{2}{\mathrm{O}}_{3}$ single crystal from viewpoint transition process free exciton to STE. succeed measuring PL rise time ($\ensuremath{\sim}24$ ps) at 8 K corresponding tunneling through barrier between and STE states adiabatic potential. From analysis based on perturbation theory for considering exciton-phonon interactions, we obtain following results....
Abstract We have investigated photoluminescence (PL) and absorption properties of a β‐Ga 2 O 3 single crystal from the viewpoint stability self‐trapped excitons (STEs). A broad PL band with large Stokes shift, which is conventionally assigned to STE, was observed. To reveal we precisely measured temperature dependence Urbach tails in spectra. It confirmed that at all temperatures converge into specific point, verifies validity treatment tail. analysed exponential slope, so‐called steepness...
Increasing demand for higher data rates in centers and high-performance computing systems require optical interconnects that support more than 100 Gbps-per-lane.Meanwhile, as optics are packed ever closer to Ethernet switches electronic processors, both operating temperatures power consumptions increase, resulting increasing operational environmental costs.In this work we present our recent results on a two-channel energy-efficient directly-modulated membrane laser array SiO 2 /Si with...
We present a directly modulated membrane laser on high-thermal-conductivity SiC exhibiting >100-GHz bandwidth. A -40GHz relaxation oscillation frequency, owing to low thermal resistance and high optical confinement, -95-GHz photon-photon resonance are achieved. Net 239.3-Gbit/s PAM-4 transmission over 2-km standard single-mode fibre is demonstrated.
We demonstrate a heterogeneous integration of electrically-pumped membrane lasers and semiconductor optical amplifiers (SOAs) on thin-film lithium niobate (TFLN) platform by micro-transfer-printing (μTP) method. Thanks to the low coupling loss (∼1.0 dB) between InP-based photonic devices TFLN waveguides, mW-class output power laser low-power-consumption SOA are achieved. A 128-Gbit/s non-return-to-zero (NRZ) signal modulation is also demonstrated with Mach-Zehnder modulator an integrated...
We demonstrate DML-based net 325-Gb/s at back-to-back and 321.24-Gb/s after 2-km standard single-mode fiber transmissions for >300-Gbps/λ short-reach optical interconnects. Our rate performance denotes an increase of ∼34% compared to our previous works, while the pre-FEC rates are >400 Gbps. The DML transmitter is based on a PPR-enhanced, >100-GHz-bandwidth DML, fabricated by novel membrane-III-V-on-SiC technology. Also wide-band, entropy-loaded DMT modulation utilized adaptive algorithm via...
We investigate the temperature dependence of dynamic characteristics a 1.3-μm InGaAlAs-based directly modulated membrane laser on SiC substrate. The is fabricated by combining direct wafer bonding and InP substrates using very thin (∼10 nm) oxide layer epitaxial regrowth InP/SiC template. structure with high thermal conductivity (490 Wm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> K ) moderate refractive index (∼2.6) ensures both...
Following the demand for 1.6 Tbps and beyond data rates lower power consumption transceivers in center networks related systems, we present first 16-channel directly modulated laser (DML) array exhibiting photon-photon resonance (PPR) effect. Bandwidths of ∼50 GHz at bias currents between 6.1 ∼ 9.2 mA were achieved all 16 channels a membrane on SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /Si with optimized integrated optical...
Record DML-based 325-Gb/s (BTB) and 321.24-Gb/s (2-km SSMF) transmissions are demonstrated based on a >100-GHz bandwidth membrane DML-on-SiC, by utilizing digitally- preprocessed analog multiplexer adaptive entropy-loaded DMT modulation, surpassing our previous record ~34%.
Near-future upgrades of intra data center networks and high-performance computing systems would require optical interconnects capable operating at beyond 100 Gbps/lane. In order for this evolution to be achieved in a sustainable way, high-speed yet energy-efficient transceivers are need. Towards direction we have previously demonstrated directly-modulated lasers (DMLs) 50 Gbps/lane with sub-pJ/bit efficiencies based on our novel membrane-III-V-on-Si technology. However, there exists an...
This paper summarizes various experimental results on the characterization of novel spiking membrane lasers SiO2/Si and their dynamics. The ultra-thin (<350-nm-thick) III-V structure in a very high optical confinement factor which is suitable for both increasing processing speeds minimizing power consumptions. Moreover, generation we rely bi-modal dynamics based integrated feedback, more efficient approach than other methods that (slower) carrier-photon Based this, report first (to best our...
We have investigated the characteristics of multi-photon absorption (MPA) in a β-Ga2O3 single crystal at room temperature using photoluminescence (PL) self-trapped exciton (STE) as probe. From analysis excitation fluence dependence integrated STE-PL intensities various photon energies, we clearly confirmed occurrence two-, three-, four-, and five-photon processes. The optical transition energies four- processes are almost consistent with between lower-lying valence bands conduction-band...
We present an all-optical photonic spiking neuron based on a membrane laser silicon with optical feedback. Ultrafast dynamics ~200-ps refractory periods using 10-GHz signals are demonstrated, at laser-energy cost of ~10 pJ/spike.
Micro-transfer-printed InP-based membrane devices are fabricated on thin-film lithium niobite (TFLN). For ultra-low coupling loss (~1.0 dB), we use an InP inverse taper waveguide covered with stress-controlled SiON film. We demonstrate 128-Gbit/s NRZ signal modulation using a TFLN Mach-Zehnder modulator integrated laser.
We have investigated the photoluminescence (PL) polarization characteristics of self-trapped exciton (STE) in an undoped β-Ga2O3 single crystal at 77 K under three-photon excitation. From analysis characteristics, we found that STE PL is polarized almost parallel to a-axis. The STE-PL corresponds orientation hole which was previous works using electron-paramagnetic-resonance experiment and a first-principles calculation.
Membrane lasers on a SiC substrate offer high-speed direct modulation due to the high thermal dissipation and large optical confinement provided by SiC's high-thermal conductivity moderate refractive index (∼2.6). A remaining problem is coupling loss single-mode fiber (SMF) arising from difficulty in producing waveguide whose effective matches that of fiber. Here, overcome this, partially removed dip filled with SiO2, its surface planarized enable fabrication membrane spot-size converters...
We present the first 16-channel membrane laser array exhibiting photon-photon resonance, achieving 50-GHz bandwidths and <130 fJ/bit energies, for 1.6 Tbps transceivers. Additionally, we have showcased ultra-fast energy-efficient spiking dynamics neuromorphic applications.
100-GBaud NRZ, 2-km transmission is demonstrated using a 16-channel O-band membrane III-V directly-modulated laser array on SiO2/Si with integrated optical feedback. Owing to the photonphoton resonance bandwidth-enhancement effect, ~50 GHz bandwidths at low bias currents were achieved, resulting in <130 fJ/bit laser-operating energies.
We demonstrate optical amplifier-free transmission over 2 km with 100-GBaud PAM-4 using a spot-size-converter-integrated directly modulated membrane laser on SiC substrate. The spot-size converter SiOx waveguide is fabricated by partial removal of SiC, resulting in fibre-coupling loss 2.7 dB.
The stability of the ultrafast spiking effect in membrane III- V lasers on Si with optical feedback is experimentally evaluated for neuromorphic neural network PICs. Stable operation, thresholds, and refractory periods are obtained two different at bias current regions.
We have developed directly modulated membrane distributed reflector lasers using optical feedback from a DBR or an external waveguide. High-speed modulation with low power consumption is achieved due to photon-photon resonance and detuned loading effects.
A membrane-III-V-on-Si laser with a ~47.5-GHz bandwidth is demonstrated by achieving stable photon-photon resonance. Direct modulation of 60-GBaud PAM-4 under KP4-FEC (net 113.42 Gbps) over 2-km SSMF 0.17 pJ/bit at 25 °C and 0.34 50 have been achieved.
We demonstrate continuous-wave operation of 1.3-μm membrane distributed reflector lasers on SiC at a 130ºC stage temperature. The laser, with its large thermal conductivity and optical confinement, is promising for high-temperature operation.
Directly-modulated membrane lasers on SiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> /Si with ~60-GHz bandwidths are fabricated using an optimized longitudinal design for photon-photon resonance. A two-channel array exhibits 2×112 Gbps NRZ modulation over 2-km transmissions, consuming <0.3 pJ/bit operating energy.