Papers - Ota, Yasutomo

Topological nanophotonics and topological lasers

Y Ota, Y Arakawa, S Iwamoto

JSAP-OSA Joint Symposia, 13a_N404_7 (Optics InfoBase Conference Papers)   2021

Joint Work

Semiconductor Topological Nanophotonics

Y Ota, Y Arakawa, S Iwamoto

2021 IEEE International Electron Devices Meeting (IEDM), 38.5. 1-38.5. 4 (Technical Digest - International Electron Devices Meeting, IEDM)  2021-December   38.5.1 - 38.5.4 2021

Joint Work,  ISSN  01631918

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We will discuss possible applications of topological photonics to photonic integrated circuit technologies. We design nanophotonic elements based on topological edge states emerging at the exteriors of bulk structures and apply them to compact semiconductor lasers and waveguides. Such topological photonic devices are known to be immune to fabrication imperfections and therefore are suitable for building robust optical circuitry. We also address the idea of topological high-power lasers that take advantage of topological edge states for robust single mode lasing.

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One-side excited one-way modes in nonreciprocal waveguides

T Liu, Y Ota, S Iwamoto

JSAP-OSA Joint Symposia, 10p_N404_5 (Optics InfoBase Conference Papers)   2021

Joint Work

Intrinsic circularly polarized H1 photonic crystal cavity modes near exceptional points

CF Fong, Y Ota, Y Arakawa, S Iwamoto, YK Kato

JSAP-OSA Joint Symposia, 10p_N404_7 (Optics InfoBase Conference Papers)   2021

Joint Work

Hybrid integrated light sources on silicon assembled by transfer printing

Y Ota, S Iwamoto, Y Arakawa

2021 IEEE Photonics Conference (IPC), 1-2 (2021 IEEE Photonics Conference, IPC 2021 - Proceedings)   2021

Joint Work

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We will discuss the hybrid integration of micro/nanoscale light sources on silicon photonics circuits with transfer printing, which is based on pick-and-place assembly using a viscoelastic stamp. Various light sources including quantum-dot single-photon sources are readily and flexibly integrated on silicon with high positioning accuracy.

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Fabrication of valley photonic crystals with CMOS-compatible process

T Yamaguchi, H Yoshimi, M Seki, M Ohtsuka, N Yokoyama, Y Ota, ...

2021 26th Microoptics Conference (MOC), 1-2 (26th Microoptics Conference, MOC 2021)   2021

Joint Work

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We demonstrated the fabrication of silicon valley photonic crystal structures with triangular air holes by using photolithography for the first time. The mask patterns we newly designed enable the formation of triangular air holes with reasonably high accuracy. This is an important step toward CMOS-compatible topological nanophotonics.

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Design of a defect-based photonic crystal nanobeam cavity robustly coupled to an underlying SiN waveguide

N Pholsen, Y Ota, R Katsumi, Y Arakawa, S Iwamoto

JSAP Annual Meetings Extended Abstracts The 68th JSAP Spring Meeting 2021 …  2021

Joint Work

Si CMOS ring resonator device for synthetic dimension photonics

A Balcytis, T Ozawa, Y Ota, S Iwamoto, J Maeda, T Baba

JSAP Annual Meetings Extended Abstracts The 68th JSAP Spring Meeting 2021 …  2021

Joint Work

Investigation of enlarged topological band gaps in magneto-optical epsilon-near-zero photonic crystals

T Liu, N Kobayashi, K Ikeda, Y Ota, S Iwamoto

JSAP Annual Meetings Extended Abstracts The 68th JSAP Spring Meeting 2021 …  2021

Joint Work

Efficient single photon sources transfer-printed on Si with unidirectional light output

R Katsumi, Y Ota, T Tajiri, M Kakuda, S Iwamoto, H Akiyama, Y Arakawa

CLEO: QELS_Fundamental Science, FF2D. 3 (OSA)  2020-May 2020

Research paper (scientific journal), Joint Work, Accepted,  ISSN  2160-9020

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We report efficient quantum-dot single-photon sources with unidirectional output integrated on Si by transfer printing. The device was designed to be robust against misalignment accompanied by the hybrid integration. Efficient single-photon generation was experimentally Confirmed.

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Active topological photonics

Y Ota, K Takata, T Ozawa, A Amo, Z Jia, B Kante, M Notomi, Y Arakawa, ...

Nanophotonics 9 (3), 547-567 (De Gruyter)  9 ( 3 ) 547 - 567 2020

Research paper (scientific journal), Joint Work, Accepted,  ISSN  2192-8606

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Topological photonics has emerged as a novel route to engineer the flow of
light. Topologically-protected photonic edge modes, which are supported at the
perimeters of topologically-nontrivial insulating bulk structures, have been of
particular interest as they may enable low-loss optical waveguides immune to
structural disorder. Very recently, there is a sharp rise of interest in
introducing gain materials into such topological photonic structures, primarily
aiming at revolu-tionizing semiconductor lasers with the aid of physical
mechanisms existing in topological physics. Examples of re-markable
realizations are topological lasers with unidirectional light output under
time-reversal symmetry breaking and topologically-protected polariton and
micro/nano-cavity lasers. Moreover, the introduction of gain and loss provides
a fascinating playground to explore novel topological phases, which are in
close relevance to non-Hermitian and parity-time symmetric quantum physics and
are in general difficult to access using fermionic condensed matter systems.
Here, we review the cutting-edge research on active topological photonics, in
which optical gain plays a pivotal role. We discuss recent realizations of
topological lasers of various kinds, together with the underlying physics
explaining the emergence of topological edge modes. In such demonstrations, the
optical modes of the topological lasers are deter-mined by the dielectric
structures and support lasing oscillation with the help of optical gain. We
also address recent researches on topological photonic systems in which gain
and loss themselves essentially influence on topological prop-erties of the
bulk systems. We believe that active topological photonics provides powerful
means to advance mi-cro/nanophotonics systems for diverse applications and
topological physics itself as well.


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Fabrication and optical characterization of photonic crystal nanocavities with electrodes for gate-defined quantum dots

T Tajiri, Y Sakai, K Kuruma, SM Ji, H Kiyama, A Oiwa, J Ritzmann, ...

Japanese Journal of Applied Physics 59 (SG), SGGI05 59 ( SGGI05 ) 1 - 6 2020

Research paper (scientific journal), Joint Work, Accepted

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Surface-passivated high-Q GaAs photonic crystal nanocavity with quantum dots

K Kuruma, Y Ota, M Kakuda, S Iwamoto, Y Arakawa

APL Photonics 5 (4), 046106 (AIP Publishing)  5 ( 4 ) 046106 - 046106 2020

Research paper (scientific journal), Joint Work, Accepted,  ISSN  2378-0967

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Photonic crystal (PhC) nanocavities with high quality (Q) factors have
attracted much attention because of their strong spatial and temporal light
confinement capability. The resulting enhanced light-matter interactions are
beneficial for diverse photonic applications, ranging from on-chip optical
communications to sensing. However, currently achievable Q factors for active
PhC nanocavities, which embed active emitters inside, are much lower than those
of the passive structures because of large optical loss, presumably originating
from light scattering by structural imperfections and/or optical absorptions.
Here, we demonstrate a significant improvement of Q factors up to ~160,000 in
GaAs active PhC nanocavities using a sulfur-based surface passivation
technique. This value is the highest ever reported for any active PhC
nanocavities with semiconductor quantum dots. The surface-passivated cavities
also exhibit reduced variation in both Q factors and cavity resonant
wavelengths. We find that the improvement in the cavity performance presumably
arises from suppressed light absorption at the surface of the PhC's host
material by performing a set of PL measurements in spectral and time domains.
With the surface passivation technique, we also demonstrate a strongly-coupled
single quantum dot-cavity system based on a PhC nanocavity with a high Q factor
of ~100,000. These results will pave the way for advanced quantum dot-based
cavity quantum electrodynamics and for GaAs micro/nanophotonic applications
containing active emitters.


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Strong coupling between a single quantum dot and an L4/3 photonic crystal nanocavity

K Kuruma, Y Ota, M Kakuda, S Iwamoto, Y Arakawa

Applied Physics Express 13 (8), 082009 (IOP PUBLISHING LTD)  13 ( 8 )  2020

Research paper (scientific journal), Joint Work, Accepted,  ISSN  1882-0778

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We demonstrate strong coupling between a single quantum dot (QD) and a GaAs-based L4/3-type photonic crystal nanocavity. The L4/3 cavity supports a high theoreticalQfactor (similar to 8 x 10(6)), a small mode volume [similar to 0.32 (lambda/n)(3)], and an electric field distribution with the maximum electric field lying within the host dielectric material, which facilitates strong coupling with a QD. We fabricated L4/3 cavities and observed a highQfactor over 80 000 using photoluminescence measurement. We confirmed strong coupling between a single QD and an L4/3 cavity with aQfactor of 33 000 by observing a clear anti-crossing in the spectra.

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Slow light waveguides in topological valley photonic crystals

H Yoshimi, T Yamaguchi, Y Ota, Y Arakawa, S Iwamoto

Optics letters 45 (9), 2648-2651 (The Optical Society)  45 ( 9 ) 2648 - 2648 2020

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0146-9592

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Slow Light Waveguide Based on Topological Edge States in Valley Photonic Crystals

H Yoshimi, T Yamaguchi, R Katsumi, Y Ota, Y Arakawa, S Iwamoto

CLEO: Science and Innovations, STu3J. 7 (OSA)  2020-May 2020

Research paper (scientific journal), Joint Work, Accepted,  ISSN  10928081

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We demonstrate slow light waveguides using topological valley kink states. We found in-gap high-group-index modes at bearded interfaces of silicon-based valley photonic crystals, clearing the path to build topologically-protected slow light waveguides only using semiconductors.

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Microcavity-based Generation of Full Poincar\'{e} Beams with Arbitrary Skyrmion Numbers

W Lin, Y Ota, Y Arakawa, S Iwamoto

arXiv preprint arXiv:2006.15493  2020

Research paper (scientific journal), Joint Work, Accepted

In situ wavelength tuning of quantum-dot single-photon sources integrated on a CMOS-processed silicon waveguide

R Katsumi, Y Ota, A Osada, T Tajiri, T Yamaguchi, M Kakuda, S Iwamoto, ...

Applied Physics Letters 116 (4), 041103 (AIP Publishing)  116 ( 4 ) 041103 - 041103 2020

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0003-6951

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Silicon quantum photonics provides a promising pathway to realize large-scale
quantum photonic integrated circuits (QPICs) by exploiting the power of
complementary-metal-oxide-semiconductor (CMOS) technology. Toward scalable
operation of such silicon-based QPICs, a straightforward approach is to
integrate deterministic single-photon sources (SPSs). To this end, hybrid
integration of deterministic solid-state SPSs, such as those based on InAs/GaAs
quantum dots (QDs), is highly promising. However, the spectral and spatial
randomness inherent in the QDs pose a serious challenge for scalable
implementation of multiple identical SPSs on a silicon CMOS chip. To overcome
this challenge, we have been investigating a new hybrid integration technique
called transfer printing, which is based on a pick-and-place operation and
allows for the integration of desired QD SPSs on any locations on the silicon
CMOS chips at will. Nevertheless, even in this scenario, in-situ fine tuning
for perfect wavelength matching among the integrated QD SPSs will be required
for interfering photons from the dissimilar sources. Here, we demonstrate
in-situ wavelength tuning of QD SPSs integrated on a CMOS silicon chip. To
thermally tune the emission wavelengths of the integrated QDs, we augmented the
QD SPSs with optically driven heating pads. The integration of all the
necessary elements was performed using transfer printing, which largely
simplified the fabrication of the three-dimensional stack of micro/nanophotonic
structures. We further demonstrate in-situ wavelength matching between two
dissimilar QD sources integrated on the same silicon chip. Our
transfer-printing-based approach will open the possibility for realizing
large-scale QPICs that leverage CMOS technology.


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Fabrication of Monocrystalline Magneto-optical Garnet Thin Film on Insulator Substrates for Exploring Magneto-nanophotonics

S Gao, Y Ota, F Tian, Y Arakawa, S Iwamoto

JSAP Annual Meetings Extended Abstracts The 67th JSAP Spring Meeting 2020 …  2020

Joint Work

Growth-Rate-Dependent Properties of GaSb/GaAs Quantum Dots on (001) Ge Substrate by Molecular Beam Epitaxy

Zon, Phienlumlert Pakawat, Thainoi Supachok, Kiravittaya Suwit, Tandaechanurat Aniwat, Nuntawong Noppadon, Sopitpan Suwat, Yordsri Visittapong, Thanachayanont Chanchana, Kanjanachuchai Songphol, Ratanathammaphan Somchai, Panyakeow Somsak, Ota Yasutomo, Iwamoto Satoshi, Arakawa Yasuhiko

PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE 216 ( 1 )  2019.01

Research paper (scientific journal), Joint Work, Accepted,  ISSN  1862-6300

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