Yasutomo Ota
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View article: BIC slow light waveguides based on interband coupling
BIC slow light waveguides based on interband coupling Open
Harnessing bound states in the continuum (BICs) for guiding light in leaky environments has unlocked new possibilities in photonic integrated circuits. BIC confinement enables low-loss waveguiding of leaky transverse-magnetic (TM) modes in…
View article: Design of Ultrathin Faraday Rotators based on All-dielectric Magneto-optical Metasurfaces at the Telecommunication Band
Design of Ultrathin Faraday Rotators based on All-dielectric Magneto-optical Metasurfaces at the Telecommunication Band Open
Magneto-optical (MO) interactions offer a direct route to nonreciprocal optical devices but are intrinsically weak in the optical domain, posing a major challenge in downsizing MO functional devices. In this study, we present a design stra…
View article: Quantum-dot single-photon source based on a two-dimensional photonic crystal nanocavity transfer-printed on a Si wire waveguide
Quantum-dot single-photon source based on a two-dimensional photonic crystal nanocavity transfer-printed on a Si wire waveguide Open
We report a quantum-dot single-photon source (QD SPS) with a two-dimensional photonic crystal (2D PhC) nanocavity hybrid-integrated on a low-loss hydrogenated amorphous silicon waveguide via transfer printing. The large bandgap effect of t…
View article: A Phosphorus(V)‐Centered Porphyrin Having Redox‐ and Air‐Stable Axial P–H Bonds
A Phosphorus(V)‐Centered Porphyrin Having Redox‐ and Air‐Stable Axial P–H Bonds Open
Phosphorus(V)‐centered porphyrins (P(V)‐porphyrins) are an important class of functional dyes in many fields of research, and axial ligands on the phosphorus atom affect the electronic properties of P(V)‐porphyrins and add functions. Herei…
View article: Experimental realization of wide-mode-area slow light modes in valley photonic crystal heterostructure waveguides
Experimental realization of wide-mode-area slow light modes in valley photonic crystal heterostructure waveguides Open
We experimentally realized wide-mode-area slow-light modes in valley photonic crystals (VPhCs) heterostructure waveguides. The waveguides are fabricated on a silicon slab by inserting gapless photonic graphene layers with varying widths an…
View article: Experimental realization of wide-mode-area slow light modes in valley photonic crystal heterostructure waveguides
Experimental realization of wide-mode-area slow light modes in valley photonic crystal heterostructure waveguides Open
We experimentally realized wide-mode-area slow-light modes in valley photonic crystals (VPhCs) heterostructure waveguides. The waveguides are fabricated on a silicon slab by inserting gapless photonic graphene layers with varying widths an…
View article: Slow light waveguides based on bound states in the continuum
Slow light waveguides based on bound states in the continuum Open
The concept of bound states in the continuum (BIC) has been advancing light confinement technology in leaky environments. In this Letter, we propose and numerically demonstrate a slow light waveguide based on a BIC mode. We considered a wa…
View article: Transfer-printed nanophotonic waveguide on an erbium doped crystal towards hybrid photonic quantum devices
Transfer-printed nanophotonic waveguide on an erbium doped crystal towards hybrid photonic quantum devices Open
We report the design, fabrication and optical characterization of silicon nanophotonic waveguides on an erbium doped crystal. The silicon waveguide allows for efficient optical addressing of erbium ions embedded near the crystal surface. W…
View article: Electrically tunable InAs/GaAs QD in a nanocavity with a transfer-printed ITO electrode
Electrically tunable InAs/GaAs QD in a nanocavity with a transfer-printed ITO electrode Open
We demonstrate the electrical tuning of InAs/GaAs quantum dots (QDs) embedded in a photonic-crystal (PhC) cavity with transparent indium tin oxide (ITO) electrodes hybrid-integrated by transfer printing. The design includes spacer layers b…
View article: On-chip optical skyrmionic beam generators
On-chip optical skyrmionic beam generators Open
Optical skyrmion beams, which encompass a two-dimensional topology in their spatial structures, are promising candidates for ultra-dense optical communications and advanced matter manipulation. Generating such light beams using a chip-base…
View article: Nonadiabatic nonlinear non-Hermitian quantized pumping
Nonadiabatic nonlinear non-Hermitian quantized pumping Open
We analyze a quantized pumping in a nonlinear non-Hermitian photonic system with nonadiabatic driving. The photonic system is made of a waveguide array, where the distances between adjacent waveguides are modulated. It is described by the …
View article: On-Chip Optical Skyrmionic Beam Generators
On-Chip Optical Skyrmionic Beam Generators Open
Optical skyrmion beams, which encompass two-dimensional topology in their spatial structures, are promising for ultra-dense optical communications and advanced matter manipulation. Generating such light beams via a chip-based approach will…
View article: Corrigendum: Design of GaAs microcavity on SiN waveguide for efficient single-photon generation by resonant excitation (2024 Mater. Quantum. Technol. 4 026201)
Corrigendum: Design of GaAs microcavity on SiN waveguide for efficient single-photon generation by resonant excitation (2024 Mater. Quantum. Technol. 4 026201) Open
This corrigendum resolves an error in the plot of quality factors as a function of number of air holes in figure 5(a) and its caption. In the original version, the symbols for the plot of quality factors before and after optimization were …
View article: Reconfigurable synthetic dimension frequency lattices in an integrated lithium niobate ring cavity
Reconfigurable synthetic dimension frequency lattices in an integrated lithium niobate ring cavity Open
Harnessing non-spatial properties of photons as if they represent an additional independent coordinate underpins the emerging synthetic dimension approach. It enables probing of higher-dimensional physical models within low-dimensional dev…
View article: Space-Time Hopfion Crystals
Space-Time Hopfion Crystals Open
Hopfions, higher-dimensional topological quasiparticles with sophisticated 3D knotted spin textures discovered in condensed matter and photonic systems, show promise in high-density data storage and transfer. Here we present crystalline st…
View article: Wide-mode-area slow light waveguides in valley photonic crystal heterostructures
Wide-mode-area slow light waveguides in valley photonic crystal heterostructures Open
We designed slow-light waveguides with a wide mode area based on slab-type valley photonic crystal (VPhC) heterostructures which are composed of a graphene-like PhC sandwiched by two topologically distinct VPhCs. The group velocity of the …
View article: Design of GaAs microcavity on SiN waveguide for efficient single-photon generation by resonant excitation
Design of GaAs microcavity on SiN waveguide for efficient single-photon generation by resonant excitation Open
Silicon nitride (SiN) photonic circuits are attracting significant interest as a platform for photonic quantum information processing. Integration of deterministic single photon sources (SPSs) is required for large-scale single-photon-base…
View article: Wide-mode-area slow light waveguides in valley photonic crystal heterostructures
Wide-mode-area slow light waveguides in valley photonic crystal heterostructures Open
We designed slow-light waveguides with a wide mode area based on slab-type valley photonic crystal (VPhC) heterostructures which are composed of a graphene-like PhC sandwiched by two topologically distinct VPhCs. The group velocity of the …
View article: Telecom‐Band Quantum Dots Compatible with Silicon Photonics for Photonic Quantum Applications
Telecom‐Band Quantum Dots Compatible with Silicon Photonics for Photonic Quantum Applications Open
Silicon photonics is promising for quantum photonics applications owing to its large‐scale and high‐performance circuitry enabled by complementary‐metal‐oxide‐semiconductor fabrication processes. However, there is a lack of bright single‐p…
View article: Efficient light couplers to topological slow light waveguides in valley photonic crystals
Efficient light couplers to topological slow light waveguides in valley photonic crystals Open
We numerically and experimentally demonstrate efficient light couplers between topological slow light waveguides in valley photonic crystals (VPhCs) and wire waveguides. By numerical simulations, we obtained a high coupling efficiency of −…
View article: Hybrid distributed Bragg reflector laser on Si with a transfer printed InAs/GaAs quantum dot amplifier
Hybrid distributed Bragg reflector laser on Si with a transfer printed InAs/GaAs quantum dot amplifier Open
We demonstrate a hybrid integrated laser by transfer printing an InAs/GaAs quantum dot (QD) amplifier on a Si waveguide with distributed Bragg reflectors (DBRs). The QD waveguide amplifier of 1.6 mm long was patterned in the form of an air…
View article: Reconfigurable synthetic dimension frequency lattices in an integrated lithium niobate ring cavity
Reconfigurable synthetic dimension frequency lattices in an integrated lithium niobate ring cavity Open
Harnessing non-spatial properties of photons as if they represent an additional independent coordinate underpins the emerging synthetic dimension approach. It enables probing of higher-dimensional physical models within low-dimensional dev…
View article: Efficient light couplers to topological slow light waveguides in valley photonic crystals
Efficient light couplers to topological slow light waveguides in valley photonic crystals Open
We numerically and experimentally demonstrate efficient light couplers between topological slow light waveguides in valley photonic crystals (VPhCs) and wire waveguides. By numerical simulations, we obtained a high coupling efficiency of -…
View article: High-Q two-dimensional photonic crystal nanocavity on glass with an upper glass thin film
High-Q two-dimensional photonic crystal nanocavity on glass with an upper glass thin film Open
We numerically analyze two-dimensional photonic crystal (PhC) nanocavities on glass with a thin glass film on top of the structure. We investigated a multi-step heterostructure GaAs PhC nanocavity located on glass. We found that covering t…
View article: Nonadiabatic nonlinear non-Hermitian quantized pumping
Nonadiabatic nonlinear non-Hermitian quantized pumping Open
We analyze a quantized pumping in a nonlinear non-Hermitian photonic system with nonadiabatic driving. The photonic system is made of a waveguide array, where the distances between adjacent waveguides are modulated. It is described by the …
View article: Enhanced Magneto‐Optical Effects in Epsilon‐Near‐Zero Indium Tin Oxide at Telecommunication Wavelengths
Enhanced Magneto‐Optical Effects in Epsilon‐Near‐Zero Indium Tin Oxide at Telecommunication Wavelengths Open
Epsilon‐near‐zero (ENZ) materials exhibit near‐zero permittivity and induce various intriguing linear and nonlinear optical phenomena. Magneto‐optical (MO) effects, which are notoriously weak in the optical domain, have been predicted to b…
View article: Valley photonic crystal waveguides fabricated with CMOS-compatible process
Valley photonic crystal waveguides fabricated with CMOS-compatible process Open
Valley photonic crystal (VPhC) waveguides have attracted much attention because of their ability to enable robust light propagation against sharp bends. However, their demonstration using a CMOS-compatible process suitable for mass product…
View article: Faraday rotator based on a silicon photonic crystal slab on a bismuth-substituted yttrium iron garnet thin film
Faraday rotator based on a silicon photonic crystal slab on a bismuth-substituted yttrium iron garnet thin film Open
We report the design of an ultrathin Faraday rotator consisting of a silicon photonic crystal (PhC) slab on a bismuth-substituted yttrium iron garnet (Bi:YIG) thin film. By directing light into guided modes in the Bi:YIG layer via diffract…
View article: Valley photonic crystal waveguides fabricated with CMOS-compatible process
Valley photonic crystal waveguides fabricated with CMOS-compatible process Open
Valley photonic crystal (VPhC) waveguides have attracted much attention because of their ability to enable robust light propagation against sharp bends. However, their demonstration using a complementary metal-oxide-semiconductor (CMOS)-co…
View article: Micro-Transfer-Printed Membrane Distributed Reflector Lasers on Si Waveguide Modulated With 50-Gbit/s NRZ Signal
Micro-Transfer-Printed Membrane Distributed Reflector Lasers on Si Waveguide Modulated With 50-Gbit/s NRZ Signal Open
In this work, we fabricate directly modulated membrane distributed reflector (DR) lasers on a Si waveguide by utilizing micro-transfer printing method. Micro-transfer printing enables low-loss coupling between the lasers and the silicon ph…