Papers - Ota, Yasutomo

Photonic crystal nanocavity laser with single quantum dot gain

Nomura M., Kumagai N., Iwamoto S., Ota Y., Arakawa Y.

2009 Conference on Lasers and Electro Optics and 2009 Conference on Quantum Electronics and Laser Science Conference CLEO QELS 2009  2009.11

Research paper (international conference proceedings), Joint Work, Accepted

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We demonstrate a photonic crystal nanocavity laser essentially driven by single quantum dot gain. A diluted quantum dot density (∼0.4/cavity) resulted in clear single quantum dot feature and distinct phase transition in photon correlation measurements. ©2009 IEEE.

Photonic crystal nanocavity laser with a single quantum dot gain

Nomura M., Kumagai N., Iwamoto S., Ota Y., Arakawa Y.

Optics Express 17 ( 18 ) 15975 - 15982 2009.08

Research paper (scientific journal), Joint Work, Accepted

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We demonstrate a photonic crystal nanocavity laser essentially driven by a self-assembled InAs/GaAs single quantum dot gain. The investigated nanocavities contain only 0.4 quantum dots on an average; an ultra-low density quantum dot sample (1.5 x 10⁸ cm^-2) is used so that a single quantum dot can be isolated from the surrounding quantum dots. Laser oscillation begins at a pump power of 42 nW under resonant condition, while the far-detuning conditions require ∼145 nW for lasing. This spectral detuning dependence of laser threshold indicates substantial contribution of the single quantum dot to the total gain. Moreover, photon correlation measurements show a distinct transition from anti-bunching to Poissonian via bunching with the increase of the excitation power, which is also an evidence of laser oscillation using the single quantum dot gain. © 2009 Optical Society of America.

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Vacuum Rabi splitting with a single quantum dot embedded in a H1 photonic crystal nanocavity

Ota Y., Shirane M., Nomura M., Kumagai N., Ishida S., Iwamoto S., Yorozu S., Arakawa Y.

Applied Physics Letters 94 ( 3 )  2009.02

Research paper (scientific journal), Joint Work, Accepted,  ISSN  00036951

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We report here the first observation of vacuum Rabi splitting in a single quantum dot (QD) embedded in a H1 photonic crystal nanocavity by photoluminescence measurement. The QD emission was tuned into a cavity mode by controlling the temperature. At the resonance condition, clear anticrossing with a Rabi splitting of ∼124 μeV was observed, where the cavity mode possesses the smallest mode volume V∼0.43 (λ/n)³ among strongly coupled QD-cavity systems reported to date. © 2009 American Institute of Physics.

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Photonic band-edge micro lasers with quantum dot gain

Nomura M., Iwamoto S., Tandaechanurat A., Ota Y., Kumagai N., Arakawa Y.

Optics Express 17 ( 2 ) 640 - 648 2009.01

Research paper (scientific journal), Joint Work, Accepted

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We demonstrate optically pumped continuous-wave photonic band-edge microlasers on a two-dimensional photonic crystal slab. Lasing was observed at a photonic band-edge, where the group velocity was significantly small near the K point of the band structure having a triangular lattice. Lasing was achieved by using a quantum dot gain material, which resulted in a significant decrease in the laser threshold, compared with photonic band-edge lasers using quantum well gain material. Extremely low laser thresholds of ∼80 nW at 6 K was achieved. Lasing was observed in a defect-free photonic crystal as small as ∼7 m square. © 2009 Optical Society of America.

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Photonic crystal nanocavity laser with single quantum dot gain

Nomura M., Kumagai N., Iwamoto S., Ota Y., Arakawa Y.

Optics Infobase Conference Papers  2009

Research paper (international conference proceedings), Joint Work, Accepted

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We demonstrate a photonic crystal nanocavity laser essentially driven by single quantum dot gain. A diluted quantum dot density (~0.4/cavity) resulted in clear single quantum dot feature and distinct phase transition in photon correlation measurements. © 2009 OSA.

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Enhanced photon emission and absorption of single quantum dot in resonance with two modes in photonic crystal nanocavity

Ota Y., Nomura M., Kumagai N., Watanabe K., Ishida S., Iwamoto S., Arakawa Y.

Applied Physics Letters 93 ( 18 )  2008.11

Research paper (scientific journal), Joint Work, Accepted,  ISSN  00036951

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We demonstrate simultaneous enhancement of photon emission and absorption of a single InGaAs self-assembled quantum dot (QD) in resonance with two modes in a photonic crystal nanocavity. The QD, whose ground and excited states are resonant, respectively, with the first and second lowest order cavity modes, is excited by cavity resonant excitation at the wavelength of the second order cavity mode and shows 180 times greater photon emission from the ground state than a bare QD. This large enhancement is attributed to a combination of Purcell effect, efficient photon extraction, and cavity resonant absorption enhancement. © 2008 American Institute of Physics.

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Achievement of ultra-low threshold excitation power (8 nW) in a nearly-single quantum dot nanocavity laser

Nomura M., Ota Y., Kumagai N., Iwamoto S., Arakawa Y.

2008 Conference on Quantum Electronics and Laser Science Conference on Lasers and Electro Optics CLEO QELS  2008.09

Research paper (international conference proceedings), Joint Work, Accepted

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We demonstrate photonic crystal nanocavity laser with nearly-single quantum dot gain. Continuous-wave lasing was achieved at photocarrier generation rate of 5 × 10⁹/s, corresponding to several carrier injection into nearly-single quantum dot. © 2008 IEEE.

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Efficient excitation and emission of single quantum dot by simultaneous coupling to two different photonic crystal nanocavity modes

Ota Y., Nomura M., Kumagai N., Watanabe K., Ishida S., Iwamoto S., Shirane M., Kono S., Yorozu S., Arakawa Y.

2008 Conference on Quantum Electronics and Laser Science Conference on Lasers and Electro Optics CLEO QELS  2008.09

Research paper (international conference proceedings), Joint Work, Accepted

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We utilized simultaneous coupling of higher and ground states of a single QD with two different resonant modes of a PhC nanocavity for efficient excitation and emission. Enhanced emission with strongly suppressed background was demonstrated. © 2008 IEEE.

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Large vacuum rabi splitting in single self-assembled quantum dot-nanocavity system

Nomura M., Ota Y., Kumagai N., Iwamoto S., Arakawa Y.

Applied Physics Express 1 ( 7 ) 0721021 - 0721023 2008.07

Research paper (scientific journal), Joint Work, Accepted,  ISSN  18820778

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We report on the observation of the strong-coupling regime in a single InGaAs self-assembled quantum dot (QD) and photonic crystal nanocavity system. There was a strong Interaction between the QD exciton and dlscretlzed photon mode and the strong coupling was manifest in photoluminescence data, which displayed a distinct anti-crossing in temperature tuning measurements. A vacuum Rabi splitting of 180μeV was observed, which was larger than the values given in previous studies with clear exciton polariton modes. In addition, the exciton-photon coupling strength amounted to about 90μeV. A distinct energy mixing, which resulted from the reversible photon emission process of a QD, was also observed when the system formed a QD exciton polariton state. © 2008 The Japan Society of Applied Physics.

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Refraction and diffraction by a metal-dielectric multilayered structure

Kameda S., Ohta Y., Kikutal H.

Journal of the Optical Society of America A Optics and Image Science and Vision 25 ( 4 ) 903 - 910 2008.04

Research paper (scientific journal), Joint Work, Accepted,  ISSN  10847529

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An optical refraction prism consisting of metal and dielectric, subwavelength, periodic multilayered thin films has been proposed. The multilayered structure of metal and dielectric thin films has a cylindrical dispersion surface for TM polarized light. The light behaviors are very different from those of conventional glass prisms and photonic crystal superprisms. Refraction and diffraction of the light wave for the metal-dielectric multilayered prism has been investigated by numerical simulations and graphical representation based on the dispersion surface. A prism with 0.2 μm period had an angular dispersion of 0.20̊/nm for ̃0.8 μm wavelength light. The finite thick metal-dielectric multilayered structure acted as a slab waveguide. © 2008 Optical Society of America.

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Achievement of ultra-low threshold excitation power (8 nW) in a nearly-single quantum dot nanocavity laser

Nomura M., Ota Y., Kumagai N., Iwamoto S., Arakawa Y.

Optics Infobase Conference Papers  2008

Research paper (international conference proceedings), Joint Work, Accepted

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We demonstrate photonic crystal nanocavity laser with nearly-single quantum dot gain. Continuous-wave lasing was achieved at photocarrier generation rate of 5 x 109/s, corresponding to several carrier injection into nearly-single quantum dot. © 2008 OSA / CLEO/QELS 2008.

Efficient excitation and emission of single quantum dot by simultaneous coupling to two different photonic crystal nanocavity modes

Ota Y., Nomura M., Kumagai N., Watanabe K., Ishida S., Iwamoto S., Shirane M., Kono S., Yorozu S., Arakawa Y.

Optics Infobase Conference Papers  2008

Research paper (international conference proceedings), Joint Work, Accepted

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We utilized simultaneous coupling of higher and ground states of a single QD with two different resonant modes of a PhC nanocavity for efficient excitation and emission. Enhanced emission with strongly suppressed background was demonstrated. © 2008 OSA/CLEO/QELS 2008.

Fabrication and characterization of photonic crystal nanocavity with degenerated cavity modes for generating entangled photon pairs using quantum dots

Ota Y., Nomura M., Kumagai N., Watanabe K., Ishida S., Iwamoto S., Shirane M., Kono S., Yorozu S., Arakawa Y.

Pacific Rim Conference on Lasers and Electro Optics CLEO Technical Digest  2007.12

Research paper (international conference proceedings), Joint Work, Accepted

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We successfully fabricated photonic crystal nanocavities for generating entangled photon pairs using single quantum dots. The fabricated cavities have a minimum splitting between two orthogonal dipóle modes of ∼250 μeV and measured cavity Qs of ∼2,000. A maximum fidelity of 0.95 for entangled photon pairs is expected with this cavity.

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Fabrication of photonic crystal nanocavity for generating entangled photon pairs using quantum dots

Ota Y., Nomura M., Kumagai N., Watanabe K., Ishida S., Iwamoto S., Shirane M., Kono S., Yorozu S., Arakawa Y.

2007 International Nano Optelectronics Workshop Inow    226 - 227 2007.12

Research paper (international conference proceedings), Joint Work, Accepted

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We fabricated photonic crystal nanocavities which have two orthogonal dipole modes with a minimum splitting of ∼250 μeV and measured cavity Qs of -2,000. Those cavities are applicable for generating entangled photon pairs using quantum dots. © 2007 IEEE.

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Fabrication and characterization of photonic crystal nanocavity with degenerated cavity modes for generating entangled photon pairs using quantum dots

Ota Y., Nomura M., Kumagai N., Watanabe K., Ishida S., Iwamoto S., Shirane M., Kono S., Yorozu S., Arakawa Y.

Optics Infobase Conference Papers  2007

Research paper (international conference proceedings), Joint Work, Accepted

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We successfully fabricated photonic crystal nanocavities for generating entangled photon pairs using single quantum dots. The fabricated cavities have a minimum splitting between two orthogonal dipole modes of-250 ieV and measured cavity Qs of-2,000. A maximum fidelity of 0.95 for entangled photon pairs is expected with this cavity. © CLEO Pacific Rim 2007.