Journal Papers

65. Increase in terahertz-wave generation by difference frequency mixing by overlap of exciton states in different GaAs/AlAs quantum wells and spectroscopic measurements
K. Sakaue, O. Kojima, T. Kita, M. J. Steer, R. A. Hogg
Optics Express 29, pp.24387-24395 (2021).
download from Kobe University Repository

64. Modulation of exciton states through resonant excitation by continuous wave lasers in a GaAs/AlAs multiple quantum well
O. Kojima, T. Kita, M. J. Steer, R. A. Hogg
Journal of Physics D: Applied Physics 54, 335106-1-7 (2021).

63. Photoluminescence excitation spectroscopy for structural and electronic characterization of resonant tunneling diodes for THz applications
M. Cito, O. Kojima, B. J. Stevens, T. Mukai, R. A. Hogg
AIP Advances 11, 035122-1-5 (2021).

2020

62. Resonant exciton excitation photoluminescence and dynamics in a GaAs/AlAs multiple quantum well with internal electric field   アブストラクト(訳)
O. Kojima, T. Kita, M. J. Steer, and R. A. Hogg
AIP Advances 10, 095016-1-7 (2020). download from Kobe University Repository

61. Electron transport in a silicon crystal observed by energy transfer luminescence   アブストラクト(訳)
O. Kojima, Y. Ito, T. Kita, Y. Shim
Japanese Journal of Applied Physics 59, 082005-1-4 (2020).

2019

60. Exciton dynamics as a function of excitation intensity and double-pulse excitation in cyanine molecule thin films: Toward low-power optical switches   アブストラクト(訳)
O. Kojima, J. Nagauchi, T. Kita
Journal of Applied Physics 126, 033103-1-6 (2019). download from Kobe University Repository

59. Effect of modulation of ultrafast transient carrier dynamics by interface on terahertz signal   アブストラクト(訳)
S. Yamamoto, O. Kojima, T. Kita
Journal of Physics: Conference Series 1220, 012013-1-4 (2019). download from Kobe University Repository

58. Effects of a thin nitrogen-doped layer on terahertz dynamics in GaAs containing InAs quantum dots   アブストラクト(訳)
O. Kojima, R. Izumi, T. Kita
OSA Continuum 2, pp. 1621-1628 (2019). download from Kobe University Repository

57. Broadband THz absorption spectrometer based on excitonic nonlinear optical effects
A. Majeed, P. Ivanov, B. Stevens, E. Clarke, I. Butler, D. Childs, O. Kojima, R. Hogg
Light: Science & Applications 8, 29-1-5 (2019). download from Kobe University Repository

2018

56. Wide frequency tuning of continuous terahertz wave generated by difference frequency mixing under exciton-excitation conditions in a GaAs/AlAs multiple quantum well   アブストラクト(訳)
O. Kojima, Y. Tarui, H. Shimazu, T. Kita, A. Majeed, P. Ivanov, E. Clarke, R. Hogg
Physical Review Applied 10, 044035-1-6 (2018). download from Kobe University Repository

55. Effect of lattice-mismatch strain on electron dynamics in InAs/GaAs quantum dots as seen by time-domain terahertz spectroscopy
O. Kojima, R. Izumi, T. Kita
Journal of Physics D: Applied Physics 51, 305102-1-6 (2018). download from Kobe University Repository

2017

54. Excitation of thin cyanine films via energy transfer from Si substrate   アブストラクト(訳)
Y. Ito, O. Kojima, T. Kita, Y. Shim
Journal of the Physical Society of Japan 86, 094710-1-4 (2017). download from Kobe University Repository

53. Effects of non-exciton components excited by broadband pulses on quantum beats in a GaAs/AlAs multiple quantum well
O. Kojima, Y. Iwasaki, T. Kita, K. Akahane
Scientific Reports 7, 41496-1-7 (2017). download from Kobe University Repository

2016

52. Increase in exciton decay rate due to plane-to-plane interaction between cyanine thin films   アブストラクト(訳)
J. Nagauchi, O. Kojima, T. Kita, Y. Shim
AIP Advances 6, 075209-1-7 (2016). download from Kobe University Repository

51. Effects of exciton line widths on the amplitude of quantum beat oscillations   アブストラクト(訳)
O. Kojima, T. Kita
Applied Physics Express 9, 062801-1-3 (2016). download from Kobe University Repository

2015

50. Fabrication of cyanine dye thin films grown by a layer-by-layer method
J. Nagauchi, O. Kojima, T. Kita, Y. Shim
Material Research Express 2, 076402-1-7 (2015). download from Kobe University Repository

49. Rapid dephasing related to intersubband transitions induced by exciton quantum beats observed by a pump-probe technique in a GaAs/AlAs multiple quantum well   アブストラクト(訳)
O. Kojima, K. Kojima, T. Kita, K. Akahane
Physical Review B 91, 125307-1-4 (2015). download from Kobe University Repository

2014

48. Effect of exciton oscillator strength on upconversion photoluminescence in GaAs/AlAs multiple quantum wells   アブストラクト(訳)
O. Kojima, S. Okumura, T. Kita, K. Akahane
Applied Physics Letters 105, 181901-1-3 (2014). download from Kobe University Repository

47. Control of optical properties in cyanine dye thin film fabricated by a layer-by-layer method   アブストラクト(訳)
O. Kojima, R. Fujii, T. Kita, Y. Shim
Journal of Applied Physics 115, 083503-1-4 (2014). download from Kobe University Repository

46. Pulse modulation towards low-power operation based on the quantum beat of excitons in a GaAs/AlAs multiple quantum well
O. Kojima, K. Hayashii, T. Kita, K. Akahane
Journal of Physics D: Applied Physics 47, 105101-1-5 (2014). download from Kobe University Repository

2013

45. Effects of pumping on propagation velocities of confined exciton polaritons in GaAs/AlxGa1-xAs double heterostructure thin films under resonant and non-resonant probe conditions   アブストラクト(訳)
O. Kojima, S. Ohta, T. Kita, T. Isu
Journal of Applied Physics 113, 013514-1-6 (2013). download from Kobe University Repository

44. Enhancement of optical anisotropy by interconnection effect along growth direction in multistacked quantum dots   アブストラクト(訳)
H. Tanaka, O. Kojima, T. Kita, K. Akahane
Japanese Journal of Applied Physics 52, 012001-1-4 (2013). download from Kobe University Repository

2012

43. Quantum beats of type-I and type-II excitons in an InxGa1−xAs/GaAs strained single quantum well   アブストラクト(訳)
O. Kojima, K. Mizoguchi, M. Nakayama
Journal of Applied Physics 112, 043522-1-4 (2012). download from Kobe University Repository

42. Observation of quantum beat oscillations and ultrafast relaxation of excitons confined in GaAs thin films by controlling probe laser pulses   アブストラクト(訳)
S. Ohta, O. Kojima, T. Kita, T. Isu
Journal of Applied Physics 111, 023505-1-4 (2012). download from Kobe University Repository

2011

41. Dynamics of above-barrier state excitons in multi-stacked quantum dots   アブストラクト(訳)
O. Kojima, N. Tobita, T. Kita, K. Akahane
Journal of Applied Physics 110, 093515-1-4 (2011). download from Kobe University Repository

40. Extremely uniform bound exciton states in nitrogen d-doped GaAs studied by photoluminescence spectroscopy in external magnetic fields
Y. Harada, T. Kubo, T. Inoue, O. Kojima, T. Kita
Journal of Applied Physics 110, 083522-1-5 (2011). download from Kobe University Repository

39. Saturation of Förster resonance energy transfer between two optically nonlinear cyanine dyes of small Stokes shift energies in polymer thin films   アブストラクト(訳)
O. Kojima, S. Hamano, T. Kita, O. Wada
Journal of Applied Physics 110, 083521-1-5 (2011). download from Kobe University Repository

38. Depolarization effect on optical control of exciton states confined in GaAs thin films
T. Yamashita, O. Kojima, T. Kita, T. Isu
Journal of Applied Physics 110, 043514-1-5 (2011). download from Kobe University Repository

37. Observation of phase shifts in a vertical cavity quantum dot switch
C. Jin, O. Kojima, T. Kita, O. Wada, M. Hopkinson
Applied Physics Letters 98, 231101-1-3 (2011).

36. Dephasing of excitonic polaritons confined in GaAs thin films
O. Kojima, S. Watanabe, T. Kita, O. Wada, T. Isu
Journal of Physical Society of Japan 80, 034704-1-5 (2011).

35. Propagation velocity of excitonic polaritons confined in GaAs thin films
O. Kojima, S. Watanabe, T. Kita, O. Wada, T. Isu
Physica Status Solidi C 8, pp. 378-380 (2011).

34. Interaction between conduction-band edge and nitrogen-related localized levels in nitrogen d-doped GaAs
Y. Harada, O. Kojima, T. Kita, O. Wada
Physica Status Solidi C 8, pp. 365-367 (2011).

33. Bound biexciton luminescence in nitrogen d-doped GaAs
Y. Harada, O. Kojima, T. Kita, O. Wada
Physica Status Solidi B 248, pp. 464-467 (2011).

32. Excitation power dependence of nonlinear optical response of excitons in GaAs/AlAs superlattices
T. Yamashita, O. Kojima, T. Kita, O. Wada, K. Akahane
Physica Status Solidi C 8, pp. 50-53 (2011).

31. Intraband relaxation process in highly stacked quantum dots
O. Kojima, M. Mamizuka, T. Kita, O. Wada, K. Akahane
Physica Status Solidi C 8, pp. 46-49 (2011).

2010

30. Detailed design and characterization of all-optical switches based on InAs/GaAs quantum dots in a vertical cavity
C. Jin, O. Kojima, T. Inoue, T. Kita, O. Wada, M. Hopkinson, K. Akahane
IEEE Journal of Quantum Electronics 46, pp. 1582-1589 (2010).

29. Temperature-dependent carrier tunneling for self-assembled InAs/GaAs quantum dots with a GaAsN quantum well injector
C. Jin, S. Ohta, M. Hopkinson, O. Kojima, T. Kita, O. Wada
Applied Physics Letters 96, 151104-1-3 (2010).

28. Temperature dependence of photoluminescence characteristics of excitons in stacked quantum dots and quantum dot chains
O. Kojima, H. Nakatani, T. Kita, O. Wada, K. Akahane
Journal of Applied Physics 107, 073506-1-4 (2010).

2009

27. Vertical-geometry all-optical switches based on InAs/GaAs quantum dots in a cavity
C. Jin, O. Kojima, T. Kita, O. Wada, M. Hopkinson, K. Akahane
Applied Physics Letters 95, pp. 021109 (2009).

26. Optical Kerr response to multi pump pulses on GaAs weakly confined exciton
A. Kanno, R. Katouf, O. Kojima, J. Ishi-Hayase, M. Tsuchiya, T. Isu
physica status solidi (c) 6, pp.1509-1512 (2009).

25. Exciton response controlled by introducing a spacer layer in nitrided InAs quantum dots
M. Mamizuka, O. Kojima, T. Inoue, T. Kita, O. Wada
physica status solidi (c) 6, pp. S146-S149 (2009).

24. Transient reflectivity response with negative time delay caused by femtosecond pulse propagation in GaAs thin films
S. Watanabe, O. Kojima, T. Kita, O. Wada, T. Isu
physica status solidi (c) 6, pp. S139-S142 (2009).

2008

23. Effects of indium segregation on optical properties of nitrogen-doped InAs/GaAs quantum dots
T. Inoue, M. Mamizuka, H. Mizuno, O. Kojima, T. Kita, O. Wada
Journal of Applied Physics 104, 103532 (2008).

22. Ultrafast All-Optical Control of Excitons Confined in GaAs Thin Films
O. Kojima, A. Miyagawa, T. Kita, O. Wada, T. Isu
Applied Physics Express 1, 112401 (2008).

21. Photoluminescence characteristics of quantum dots with electronic states interconnected along growth direction
O. Kojima, H. Nakatani, T. Kita, O. Wada, K. Akahane, M. Tsuchiya
Journal of Applied Physics 103, 113504 (2008).

20. Spectral width dependence of residual carrier effect on nonlinear optical response of weakly confined excitons
O. Kojima, T. Isu, J. Ishi-Hayase, A. Kanno, R. Katouf, M. Sasaki, M. Tsuchiya
physica status solidi (c) 5, pp. 2858-2860 (2008).

19. Ultrafast response induced by interference effects between weakly confined exciton states
O. Kojima, T. Isu, J. Ishi-Hayase, A. Kanno, R. Katouf, M.Sasaki, M. Tsuchiya
Journal of the Physical Society of Japan 77, 044701 (2008).

18. Photoluminescence dynamics of weakly confined excitons in GaAs thin films
A. Kanno, R. Katouf, O. Kojima, J. Ishi-Hayase, M.Sasaki, M. Tsuchiya, T. Isu
Journal of Luminescence 128, pp. 1069-1071 (2008).

17. Photoluminescence dynamics of coupled quantum dots
H. Nakatani, T. Kita, O. Kojima, O. Wada, K. Akahane, M. Tsuchiya
Journal of Luminescence 128, pp. 975-977 (2008).

16. Effects of excitation spectral width on decay profile of weakly confined excitons
O. Kojima, T. Isu, J. Ishi-Hayase, A. Kanno, R. Katouf, M.Sasaki, M. Tsuchiya
Journal of Luminescence 128, pp. 966-968 (2008).

15. Decay of orientational grating of weakly confined excitons in GaAs thin films
O. Kojima, T. Isu, J. Ishi-Hayase, A. Kanno, R. Katouf, M.Sasaki, M. Tsuchiya
Journal of Luminescence 128, pp. 963-965 (2008).

14. Ultrafast optical Kerr effect of excitons weakly confined in GaAs thin films
A. Kanno, R. Katouf, O. Kojima, J. Ishi-Hayase, M. Tsuchiya, T. Isu
physica status solidi (c) 5, pp. 360-363 (2008)

2007

13. Enhancement of nonlinear optical response of weakly confined excitons in GaAs thin films by spectrally rectangle-shape-pulse-excitation
O. Kojima, T. Isu, J. Ishi-Hayase, M.Sasaki, M. Tsuchiya
Journal of Physics: Conference Series 61, pp. 618-622 (2007).

12. Ultrafast nonlinear optical response of weakly confined excitons in GaAs thin films
O. Kojima, T. Isu, J. Ishi-Hayase, M.Sasaki, M. Tsuchiya
physica status solidi (c) 4, pp. 1731-1734 (2007).

11. Terahertz radiation from coherent confined optical phonons in GaAs/AlAs multiple quantum wells
M. Nakayama, K. Mizoguchi, O. Kojima, T. Furuichi, A. Mizumoto, S. Saito, A. Syouji, K. Sakai
physica status solidi (a) 204, pp. 518-521 (2007).

2006

10. 半導体多重量子井戸構造における励起子量子ビートと光学フォノンとの相互作用
中山正昭, 溝口幸司, 小島磨
固体物理 41, pp. 257-267 (2006).

9. Spectrally resolved nonlinear optical response of weakly confined excitons under femtosecond laser pulse excitation in GaAs thin films
O. Kojima, T. Isu, J. Ishi-Hayase, M. Tsuchiya
physica status solidi (c) 3, pp. 675-678 (2006).

2005

8. Intense terahertz radiation from longitudinal optical phonons in GaAs/AlAs multiple quantum wells
K. Mizoguchi, T. Furuichi, O. Kojima, M. Nakayama, S. Saito, A. Syouji, K. Sakai
Applied Physics Letters 87, pp. 093102 (2005).

7. Characteristics of coupled mode of excitonic quantum beat and coherent longitudinal optical phonon in GaAs/AlAs multiple quantum wells
T. Furuichi, K. Mizoguchi, O. Kojima, K. Akahane, N. Yamamoto, N. Ohtani, M. Nakayama
Journal of Luminescence 112, pp. 142-145 (2005).

6. Intense coherent longitudinal optical phonons in CuI thin films under exciton-excitation conditions
O. Kojima, K. Mizoguchi, M. Nakayama
Journal of Luminescence 112, pp. 80-83 (2005).

2004

5. Enhancement of coherent longitudinal optical phonon oscillations in a GaAs/AlAs multiple quantum well due to intersubband energy tuning under an electric field
O. Kojima, K. Mizoguchi, M. Nakayama
Physical Review B 70, 233306 (2004).

4. Coupled mode of the coherent optical phonon and excitonic quantum beat in GaAs/AlAs multiple quantum wells
K. Mizoguchi, O. Kojima, T. Furuichi, M. Nakayama, K. Akahane, N. Yamamoto, N. Ohtani
Physical Review B 69, 233302 (2004).

3. Enhancement of coherent LO phonons by quantum beats of excitons in GaAs/AlAs multiple quantum wells
O. Kojima, K. Mizoguchi, M. Nakayama
Journal of Luminescence 108, pp. 195-199 (2004).

2003

2. Coupling of coherent longitudinal optical phonons to excitonic quantum beats in GaAs/AlAs multiple quantum wells
O. Kojima, K. Mizoguchi, M. Nakayama
Physical Review B 68, 155325 (2003).

1999

1. Thermal-strain-induced splitting of heavy- and light-hole exciton energies in CuI thin films grown by vacuum evaporation
D. Kim, M. Nakayama, O. Kojima, I. Tanaka, H. Ichida, T. Nakanishi, H. Nishimura
Physical Review B 60, pp. 13879-13884 (1999).