Institute of Multidisciplinary Research for Advanced Materials, Tohoku University


LAST UPDATE 2021/05/18

  • 研究者氏名
    Researcher Name

    小島一信 Kazunobu KOJIMA
    准教授 Associate Professor
  • 所属
    Professional Affiliation

    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University

    計測研究部門 量子光エレクトロニクス研究分野
    Division of Measurements, Quantum Optoelectronics
  • 研究キーワード
    Research Keywords

    Wide bandgap semiconductors
    Semiconductor laser
    Photonic crystal
Research Subject
Creation of novel optical devices establishing both high output power and high efficiency

研究の背景 Background


Wide bandgap semiconductors such as gallium nitride (GaN), aluminum nitride (AlN) and zinc oxide (ZnO) are indispensable to realize high-efficient white and deep ultraviolet light sources. However, the efficiency droop majorly limits the maximum output power of the solid state light sources. Thus, breakthrough technologies to establish both high output power and high efficiency are strongly required.

研究の目標 Outcome


Novel optical device structures based on strong interaction between matter and light are studied using the wide-gap semiconductors and optical nanocavities. The wide-gap semiconductors give large oscillator strength due to their excitonic features even at room temperature, and the nanocavity accelerates the light-matter coupling. This approach offers opportunities to overcome the efficiency droop in addition to the proposal of a new design rule of optical devices.

研究図Research Figure

Fig. 1 Excitonic reflectance spectra for the three different crystal planes of bulk GaN [1]. The optical polarization of the {0001} is ordinary while that of the other two planes is extraordinary. Fig. 2 Two dimensional photoluminescence (PL) spectra plot of an InAs/GaAs quantum dot (QD) and nanocavity with various detunings [2]. Inset: PL spectrum at the point where the QD and the cavity peak showed anti-crossing. The splitting width was 0.067 nm. Fig.3 Oscillation wavelength dependence of the threshold carrier density of a semipolar InGaN laser diode structure [3].

文献 / Publications

[1] phys. stat. sol. (b) 244, 1853 (2007),
[2] Appl. Phys. Lett. 102, 011110 (2013),
[3] Jpn. J. Appl. Phys. 49, 081001 (2010).