応用物理学会春季・秋季学術講演会

Subwavelength nanowires (NWs) positioned in grooved Si photonic crystal (PhC) waveguides have recently been shown to be a promising platform to achieve high quality factor nanocavities and nanolasers operating at telecommunication wavelengths [1,2]. Its main limitation stems from the absorption cut-off of silicon that prevents NWs emitting at wavelengths shorter than 1 μm to be used. This limitation can be circumvented by using silicon nitride instead of silicon, providing that the system is properly designed [3]. We here demonstrate that the design is versatile enough to be successfully implemented in the UV and visible ranges with various materials such as ZnO NWs [4] and CsPbBr₃ perovskite NWs (Fig. 1a). In such cavities, we achieve resolution-limited quality factors larger than Q = 2100 for a mode volume V = 3.4(λ/n_SiN)³, as deduced from three-dimensional finite-difference time-domain calculations. We also demonstrate that the degree of freedom along the groove can be used to move NW-induced nanocavities in space, to position them deterministically in PhCs of different lattice constants (Fig. 1b) and in turn to tune their optical properties (Fig. 1c): not only can we shift the resonant wavelength of the NW-induced nanocavity but we can adjust absorption losses and control the cavity to NW coupling. The versatility of our multimaterial NW-based nanophotonic platform opens the path toward the realization of novel devices including movable and tunable NW nanolasers operating across the UV/VIS range.
This work was supported by JSPS KAKENHI Grant Number 15H05735.
[1] M. D. Birowosuto et al., Nature Materials 13, 279 (2014).
[2] M. Takiguchi et al., APL Photonics 2, 046106 (2017).
[3] Sergent et al., Opt. Express 13, 279 (2016).
[4] Sergent et al., ACS Photonics 4, 1040 (2017).