A5012575878- Photonic and Optical Devices
- Photonic Crystals and Applications
- Semiconductor Lasers and Optical Devices
- Semiconductor Quantum Structures and Devices
- Optical Coatings and Gratings
- Plasmonic and Surface Plasmon Research
- Semiconductor materials and devices
- Optical Network Technologies
- Fern and Epiphyte Biology
- Quantum Dots Synthesis And Properties
- Integrated Circuits and Semiconductor Failure Analysis
- Advanced Semiconductor Detectors and Materials
- Nanowire Synthesis and Applications
- Optical Coherence Tomography Applications
- Electron and X-Ray Spectroscopy Techniques
- Advanced Photonic Communication Systems
- GaN-based semiconductor devices and materials
- Ion-surface interactions and analysis
- Advancements in Photolithography Techniques
- Metamaterials and Metasurfaces Applications
- Molecular Junctions and Nanostructures
- Near-Field Optical Microscopy
- Silicon Nanostructures and Photoluminescence
- Advanced Fiber Laser Technologies
- Spectroscopy and Laser Applications
National Institute for Materials Science
2015-2024
National Institute of Advanced Industrial Science and Technology
2005-2016
University of Tsukuba
2005-2015
Nihon Institute of Medical Science
2013
Material (Belgium)
2013
Japan Science and Technology Agency
2012
NEC (Japan)
1992-2009
Photonics Electronics Technology Research Association
2001-2007
Life Science Center for Survival Dynamics, Tsukuba Advanced Research Alliance (TARA)
2007
Hokkaido University
2001
The enhanced transmission through periodic arrays of sub-wavelength holes in optically-thick metallic films has many potential applications, such as wavelength filters, light extraction from emission diodes, and subwavelength photolithography. A color filter comprising an aluminum film been fabricated. In addition to the simplicity process, enables excitation visible-range surface plasmons due its high plasma frequency. Periodic nanostructures open way for new visible filters.
We demonstrated a novel two-dimensional photonic crystal (PC) based Symmetric Mach Zehnder type all-optical switch (PC-SMZ) with InAs quantum dots (QDs) acting as nonlinear phase-shift source. The 600- ?m-long PC-SMZ having integrated wavelength-selective PC-based directional couplers and other PC components exhibited 15-ps-wide switching-window 2-ps rise/fall time at wavelength of 1.3 ?m. Nonlinear optical phase shift in the 500-?m-long straight waveguide was also achieved sufficiently low...
Self-assembled growth of quantum dots by molecular-beam epitaxy is used to form the active region a vertical-cavity surface-emitting laser (VCSEL). Ten layers InGaAs are stacked in order increase gain. This quantum-dot VCSEL has continuous-wave operating current 32 mA at room temperature. Emission spectra various injections demonstrate that lasing action associated with higher-order transition dots.
We have studied the dispersion of ultrafast pulses in a photonic crystal waveguide as function optical frequency, both experiment and theory. With phase-sensitive time-resolved near-field microscopy, light was probed inside non-invasive manner. The effect on shape determined. As frequency decreased, group velocity decreased. Simultaneously, measured were broadened during propagation, due to an increase dispersion. On top that, exhibited strong asymmetric distortion propagation distance...
Polarization- and angle-independent, dual-band metasurface thermal emitter was developed. The emits radiation at 4.26 μm 3.95 μm, conventionally used for CO2 sensing. is based on a planar Au/Al2O3/Au structure, in which orthogonal rectangular Au patches are arrayed alternately, generates nearly perfect blackbody with an emittance as high 0.97. integrated resistive heater mounted SiN membrane, so that the infrared waves produced by applying voltage. incorporated into actual sensing system...
Straight single-line-defect photonic crystal (PC) waveguides on GaAs slabs with lengths of 1, 4, and 10 mm have been fabricated. By controlling the Al content a sacrificial AlGaAs clad layer wet etching duration, PC core very smooth surface was obtained. Atomic force microscope images indicate that roughness top is less than 1 nm. An extremely low propagation loss 0.76 dB/mm for GaAs-based waveguide achieved.
Nano-photonic technologies of GaAs-based two-dimensional photonic crystal (2DPC) slab waveguides (WGs) and InAs-based quantum dots (QDs) are reviewed for a symmetrical Mach–Zehnder (SMZ) type, ultra-small ultra-fast all-optical switch (PC-SMZ) logic device. As the first phase, (∼ps) ultra-low energy (∼100 fJ) switching has been demonstrated using chip 600 μm×300 μm in size. The second phase is to create PC-SMZ-based with latch function future digital processor. One priority subjects...
We present the experimental realization of nanofiber Bragg grating (NFBG) by drilling periodic nano-grooves on a subwavelength-diameter silica fiber using focused ion beam milling technique. Using such NFBG structures we have realized cavity systems. The typical finesse is F ∼ 20 - 120 and on-resonance transmission 30 80%. Moreover structural symmetry NFBGs results in polarization-selective modes cavity. Due to strong confinement field guided mode, can become promising workbench for QED.
Abstract Optical patch antennas sandwiching dielectrics between metal layers have been used as deep subwavelength building blocks of metasurfaces for perfect absorbers and thermal emitters. However, applications these optoelectronic devices, wiring to each electrically isolated antenna is indispensable biasing current flow. Here we show that geometrically engineered metallic wires interconnecting the can function synchronize optical phases promoting coherent resonance, not only electrical...
Photonic crystals having two-dimensional periodicity on a length scale of 320–450 nm are fabricated by electron beam lithography in combination with high-aspect-ratio dry etching. To achieve three-dimensional control the optical properties, three kinds dielectric waveguide structures based AlGaAs heterostructures, that is, semiconductor-clad, air-bridge, and oxide-clad structures, investigated. The ability to guide light through such photonic crystal devices is demonstrated transmission...
We propose a polarization-discriminating Mach-Zehnder (PDMZ) all-optical switch. The switching speed of this PDMZ switch is not limited by the slow relaxation time highly efficient incoherent nonlinearities. demonstrate squarelike modulation characteristic, which necessary in most applications, at (on-off time) 40 ps. also ultrafast detector ∼8
Polarization of 8×8 vertical cavity surface emitting laser (VCSEL) arrays is completely controlled. These index-guided VCSELs have a 6×5 μm rectangular poststructure consisting DBR mirrors. All 64 emit fundamental single-mode and linearly polarized light with polarization angle deviation only 2.9°. Their output characteristics are almost the same as those conventional 6×6 polarization-uncontrolled VCSELs.
Lanthanoid series are unique in atomic elements. One reason is because they have 4f electronic states forbidding electric-dipole (ED) transitions vacuum and another very useful current-day optical technologies such as lasers fiber-based telecommunications. Trivalent Er ions well-known a key element supporting 1.5 μm band also complex photoluminescence (PL) deeply mixing ED magnetic-dipole (MD) transitions. Here we show large selective enhancement of MD radiations up to 83- 26-fold for...
High-performance ultrathin polarizers have been experimentally demonstrated employing stacked complementary (SC) metasurfaces, which were produced using nanoimprint lithography. It is determined that the metasurface composed of Ag and Au large extinction ratios exceeding 17000 12000, respectively, in spite subwavelength thickness. also shown SC structures are optimized at telecommunication wavelengths.
In recent decades, silicon photonics has attracted much attention in telecom and data-com areas. Constituted of high refractive-index contrast waveguides on silicon-on-insulator (SOI), a variety integrated photonic passive active devices have been implemented supported by excellent optical properties the mid-infrared spectrum. The main advantage is ability to use complementary metal oxide semiconductor (CMOS) process-compatible fabrication technologies, resulting high-volume production at...
We report the experimental results of a novel symmetric Mach–Zehnder (SMZ) all-optical switch. Although switching is based on band-filling effect in semiconductor waveguide, speed not restricted by slow relaxation time. obtain fully switched, nearly square modulation, which characteristic SMZ also achieve high-speed switching; full width at half-maximum obtained wave form 8 ps, only limited time resolution detection system.
Polarization control is achieved in vertical-cavity surface-emitting lasers (VCSELs) by using structurally anisotropic self-assembled quantum dots (QDs) as active layers. The dot shape long the [01̄1] direction on (100) surface. photoluminescence from has a polarization dependence whose intensity along 1.37 times stronger than that orthogonal [011] direction. QD VCSEL operates at wavelength of ground state transition. Lasing emission shows and an suppression ratio 18 dB.
The transmittance spectrum for an air-bridge type of AlGaAs photonic crystal (PC) slabs successfully fabricated was measured. It is found that the observed consistent with both theoretical band structure and calculated one. Moreover, due to modes below light line be almost 100%, indicating guided should exist. respective stop bands are in gamma-M direction TM-like TE-like modes, implying a gap exist modes. present PC very suited controlling radiation field.
Two-dimensional (2-D) photonic crystal (PC) directional couplers (DCs) that have a triangular lattice pattern of air holes in planar dielectric slab are theoretically and experimentally analyzed. Unlike the 2-D PC DC structure with rod air, which is frequently used theoretical studies, more practical DCs tend to be multimode nature exhibit large group velocity dispersion, thus creating decoupling points dispersion relation without any additional modifications structure. The lead interference...
Impact ionization coefficients for electrons and holes in InP were measured experimentally at 25–175 °C the 400–600 kV/cm electric field range with planar avalanche photodiodes, which n-InP region was separated from light absorbing InGaAs and/or InGaAsP layers. α β monotonically decreased elevated temperatures; β/α slightly increasing temperature. Comparison of experimental results Okuto–Crowell formula on impact coefficient gave phonon energy ERO=46 meV scattering mean free path λ0=41.7 Å...
A GaAs-based epitaxially regrown photonic crystal surface-emitting laser is proposed and demonstrated at room temperature. The band-structure mapped through the angular dependence of subthreshold electroluminescence, allowing coupling coefficients to be determined.
A schematic energy diagram of the present fluorescence (FL)-enhancing process including nonradiative (NR) paths that a self-assembled monolayer (SAM) blocks is presented.
Coupling of defects in one-dimensional (1D) and two-dimensional (2D) photonic crystals (PC's) is analyzed theoretically investigated numerically using the transfer-matrix method finite-difference time-domain technique. Basically, coupling behavior reflected spectra PC molecules formed by two identical atoms (single defects). In both 1D 2D cases, can be roughly classified into types based on spectral shape resulting molecules. One type atom generates clear bonding antibonding states contrast,...