Papers - Ota, Yasutomo

Self-frequency conversion nanocavity lasers

Y Ota, K Watanabe, S Iwamoto, Y Arakawa

IEICE Technical Report; IEICE Tech. Rep. 115 (46), 13-17  2015

Research paper (scientific journal), Joint Work, Accepted

Room-temperature lasing in GaAs nanowires embedding multi-stacked InGaAs/GaAs quantum dots

J Tatebayashi, S Kako, J Ho, Y Ota, S Iwamoto, Y Arakawa

CLEO: Science and Innovations, SM2F. 1 (IEEE)  2015-August   2267 2015

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

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We report the demonstration of room-temperature lasing in a single GaAs nanowire embedding 50-stacked In0.22Ga0.78As/GaAs quantum dots at a lasing emission energy of 1.37 eV with a threshold pump pulse fluence of 138 mu j/cm(2). (C) 2015 Optical Society of America

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Room-temperature lasing in a single nanowire with quantum dots

J Tatebayashi, S Kako, J Ho, Y Ota, S Iwamoto, Y Arakawa

Nature Photonics 9 (8), 501-505 (NATURE PUBLISHING GROUP)  9 ( 8 ) 501 - + 2015

Research paper (scientific journal), Joint Work, Accepted,  ISSN  1749-4885

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Semiconductor nanowire lasers are promising as ultrasmall, highly efficient coherent light emitters in the fields of nano-photonics, nano-optics and nanobiotechnology(1,2). Although there have been several demonstrations of nanowire lasers using homogeneous bulk gainmaterials(3-14) or multi-quantum-wells/disks(15-17), it is crucial to incorporate lower-dimensional quantum nano-structures into the nanowire to achieve superior device performance in relation to threshold current, differential gain, modulation bandwidth and temperature sensitivity. The quantum dot is a useful and essential that can meet these requirements(18). However, difficulties in forming stacks of quantum dots in a single nanowire hamper the realization of lasing operation. Here, we demonstrate room-temperature lasing of a single nanowire containing 50 quantum dots by properly designing the nanowire cavity and tailoring the emission energy of each dot to enhance the optical gain. Our demonstration paves the way toward ultrasmall lasers with extremely low power consumption for integrated photonic systems.

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Vacuum Rabi spectra of a single quantum emitter

Y Ota, R Ohta, N Kumagai, S Iwamoto, Y Arakawa

Physical review letters 114 (14), 143603 (AMER PHYSICAL SOC)  114 ( 14 ) 143603 - 143603 2015

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0031-9007

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We report the observation of the vacuum Rabi splitting of a single quantum emitter by measuring its direct spontaneous emission into free space. We use a semiconductor quantum dot inside a photonic crystal nanocavity, in conjunction with an appropriate cavity design and filtering with a polarizer and an aperture, enabling the extraction of the inherently weak emitter's signal. The emitter's vacuum Rabi spectra exhibit clear differences from those measured by detecting the cavity photon leakage. Moreover, we observe an asymmetric vacuum Rabi spectrum induced by interference between the emitter and cavity detection channels. Our observations lay the groundwork for accessing various cavity quantum electrodynamics phenomena that manifest themselves only in the emitter's direct spontaneous emission.

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Dynamic Nuclear Spin Polarization in the Presence of Multiple Excitonic Complexes in Single InAs/GaAs Quantum Dots at Zero Applied Magnetic Field

CF Fong, Y Ota, E Harbord, S Iwamoto, Y Arakawa

JSAP Annual Meetings Extended Abstracts The 62nd JSAP Spring Meeting 2015 …  2015

Joint Work

Theoretical analysis of nanolaser with a few quantum dot gain

V ELFVING, Y OTA, K KAMIDE, S IWAMOTO, Y ARAKAWA

JSAP Annual Meetings Extended Abstracts The 62nd JSAP Spring Meeting 2015 …  2015

Joint Work

Measuring the second-order coherence of a nanolaser by intracavity frequency doubling

Yasutomo Ota, Katsuyuki Watanabe, Satoshi Iwamoto, Yasuhiko Arakawa

Physical Review A - Atomic, Molecular, and Optical Physics 89 ( 2 )  2014.02

Research paper (scientific journal), Joint Work, Accepted,  ISSN  1050-2947

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We measured the second-order coherence at zero time delay, g(2)(0), of a high-Q photonic crystal nanocavity quantum dot laser below and above the lasing threshold, via detecting visible emission originated from the second harmonic generation (SHG) occurring within the laser cavity. The efficiency of the nonlinear frequency conversion process, defined by SHG intensity divided by the square of laser output intensity, is shown to be proportional to g(2)(0), and hence is used for the measurement. The obtained g(2)(0) values show good agreement with those measured by a Hanbury Brown-Twiss interferometer equipped with ultrafast superconducting single-photon detectors. © 2014 American Physical Society.

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Measuring the second-order coherence of a nanolaser by intracavity frequency doubling

Ota Yasutomo, Watanabe Katsuyuki, Iwamoto Satoshi, Arakawa Yasuhiko

PHYSICAL REVIEW A 89 ( 2 )  2014.02

Research paper (scientific journal), Joint Work, Accepted,  ISSN  1050-2947

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Measuring the second-order coherence of a nanolaser by intracavity frequency doubling

Yasutomo Ota, Katsuyuki Watanabe, Satoshi Iwamoto, Yasuhiko Arakawa

PHYSICAL REVIEW A (AMER PHYSICAL SOC)  89 ( 2 )  2014.02

Research paper (scientific journal), Joint Work, Accepted,  ISSN  2469-9926

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We measured the second-order coherence at zero time delay, g((2))(0), of a high-Q photonic crystal nanocavity quantum dot laser below and above the lasing threshold, via detecting visible emission originated from the second harmonic generation (SHG) occurring within the laser cavity. The efficiency of the nonlinear frequency conversion process, defined by SHG intensity divided by the square of laser output intensity, is shown to be proportional to g((2))(0), and hence is used for the measurement. The obtained g((2))(0) values show good agreement with those measured by a Hanbury Brown-Twiss interferometer equipped with ultrafast superconducting single-photon detectors.

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Circular dichroism in a three-dimensional semiconductor chiral photonic crystal

S Takahashi, T Tajiri, Y Ota, J Tatebayashi, S Iwamoto, Y Arakawa

Applied Physics Letters 105 (5), 051107 105 ( 051107 )  2014

Research paper (scientific journal), Joint Work, Accepted

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Cavity quantum electrodynamics in quantum dot-photonic crystal nanocavity coupled system with large g/κ

S Iwamoto, Y Ota, H Takagi, D Takamiya, Y Arakawa

CLEO: Science and Innovations, SM3M. 4  2014

Research paper (scientific journal), Joint Work, Accepted

Cavity Quantum Electrodynamics in Quantum Dot-Photonic Crystal Nanocavity Coupled System with Large g/kappa

Satoshi Iwamoto, Yasutomo Ota, Hiroyuki Takagi, Daisaku Takamiya, Yasuhiko Arakawa

2014 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO) (IEEE)   2014

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

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We report experimental progresses in cavity quantum electrodynamics using H1 and H0-type photonic crystal nanoacvities embedding single quantum dots. Strong coupling and enhanced optical Stark effect in these systems with large g/kappa will be discussed.

Cavity QED in Quantum Dot-photonic Crystal Nanocavity Coupled Systems

Y Arakawa, S Iwamoto, Y Ota, K Kamide

Laser Science, LTu4H. 1 (Optics InfoBase Conference Papers)   2014

Research paper (scientific journal), Joint Work, Accepted

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Frequency-doubled photonic crystal nanocavity lasers

Y Ota, K Watanabe, S Iwamoto, Y Arakawa

SPIE Newsroom  2014

Research paper (scientific journal), Joint Work, Accepted

Measuring the second-order coherence of a nanolaser by intracavity frequency doubling

Y Ota, K Watanabe, S Iwamoto, Y Arakawa

Physical Review A 89 (2), 023824  2014

Research paper (scientific journal), Joint Work, Accepted

Measurement of the second order coherence of a nanolaser through its intra-cavity second harmonic generation

Y Ota, K Watanabe, S Iwamoto, Y Arakawa

CLEO: Science and Innovations, SW1G. 2 (IEEE)  2014-January 2014

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

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We measured the second order coherence of a photonic crystal nanolaser through measuring frequency doubling occurring within the laser nanocavity. This method enables investigation of the intensity noise properties even far below the lasing threshold.

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Highly uniform, multi-stacked InGaAs/GaAs quantum dots embedded in a GaAs nanowire

J Tatebayashi, Y Ota, S Ishida, M Nishioka, S Iwamoto, Y Arakawa

Applied Physics Letters 105 (10), 103104 (AMER INST PHYSICS)  105 ( 10 )  2014

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

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We demonstrate a highly uniform, dense stack of In0.22Ga0.78As/GaAs quantum dot (QD) structures in a single GaAs nanowire (NW). The size (and hence emission energy) of individual QD is tuned by careful control of the growth conditions based on a diffusion model of morphological evolution of NWs and optical characterization. By carefully tailoring the emission energies of individual QD, dot-to-dot inhomogeneous broadening of QD stacks in a single NW can be as narrow as 9.3 meV. This method provides huge advantages over traditional QD stack using a strain-induced Stranski-Krastanow growth scheme. We show that it is possible to fabricate up to 200 uniform QDs in single GaAs NWs using this growth technique without degradation of the photoluminescence intensity. (C) 2014 AIP Publishing LLC.

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Cavity quantum electrodynamics in quantum dot-photonic crystal nanocavity coupled system with large G/k

Iwamoto S., Ota Y., Takagi H., Takamiya D., Arakawa Y.

Conference on Lasers and Electro-Optics Europe - Technical Digest (Conference on Lasers and Electro-Optics Europe - Technical Digest)  2014-January 2014

Joint Work

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We report experimental progresses in cavity quantum electrodynamics using H1 and H0-type photonic crystal nanoacvities embedding single quantum dots. Strong coupling and enhanced optical Stark effect in these systems with large g/kwill be discussed.

Measurement of Nuclear Spin Build-up Time in Single InAs/GaAs Quantum Dots by Modulated Circularly Polarized Excitation

CF Fong, Y Ota, E Harbord, S Iwamoto, Y Arakawa

JSAP Annual Meetings Extended Abstracts The 75th JSAP Autumn Meeting 2014 …  2014

Joint Work

Cavity quantum electrodynamics in quantum dot-photonic crystal nanocavity coupled system with large g/KΚ

Iwamoto S., Ota Y., Takagi H., Takamiya D., Arakawa Y.

Optics InfoBase Conference Papers (Optics InfoBase Conference Papers)   2014

Joint Work

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We report experimental progresses in cavity quantum electrodynamics using H1 and H0-type photonic crystal nanoacvities embedding single quantum dots. Strong coupling and enhanced optical Stark effect in these systems with large g/KΚ will be discussed. © 2014 OSA.