Highly efficient nonlinear optical emission from a subwavelength crystalline silicon cuboid mediated by supercavity mode

• Published in: Nature communications 2022-05, Vol.13 (1), p.2749-9, Article 2749
• Main Authors: Panmai, Mingcheng, Xiang, Jin, Li, Shulei, He, Xiaobing, Ren, Yuhao, Zeng, Miaoxuan, She, Juncong, Li, Juntao, Lan, Sheng
• Format: Article
• Language: English
• Subjects: 140/125; 142/126; 147/135; 639/624/399/1098; 639/624/399/1099; 639/624/399/354; Chip formation; Efficiency; Electric fields; Electric polarization; Electronics industry; Emitters; Fabrication; Femtosecond pulses; High temperature; Holes (electron deficiencies); Hot electrons; Humanities and Social Sciences; Injection; Integrated circuits; Light sources; Luminescence; Magnetic fields; multidisciplinary; Nanoparticles; Nonlinear optics; Optical properties; Polarization; Quantum dots; Quantum efficiency; Science; Science (multidisciplinary); Silicon; Silicon dioxide
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-022-30503-4

The low quantum efficiency of silicon (Si) has been a long-standing challenge for scientists. Although improvement of quantum efficiency has been achieved in porous Si or Si quantum dots, highly efficient Si-based light sources prepared by using the current fabrication technooloy of Si chips are still being pursued. Here, we proposed a strategy, which exploits the intrinsic excitation of carriers at high temperatures, to modify the carrier dynamics in Si nanoparticles. We designed a Si/SiO 2 cuboid supporting a quasi-bound state in the continuum (quasi-BIC) and demonstrated the injection of dense electron-hole plasma via two-photon-induced absorption by resonantly exciting the quasi-BIC with femtosecond laser pulses. We observed a significant improvement in quantum efficiency by six orders of magnitude to ~13%, which is manifested in the ultra-bright hot electron luminescence emitted from the Si/SiO 2 cuboid. We revealed that femtosecond laser light with transverse electric polarization (i.e., the electric field perpendicular to the length of a Si/SiO 2 cuboid) is more efficient for generating hot electron luminescence in Si/SiO 2 cuboids as compared with that of transverse magnetic polarization (i.e., the magnetic field perpendicular to the length of a Si/SiO 2 cuboid). Our findings pave the way for realizing on-chip nanoscale Si light sources for photonic integrated circuits and open a new avenue for manipulating the luminescence properties of semiconductors with indirect bandgaps. Enhancing the efficiency of quantum emitters is essential for exploring new functionalities. Here the authors show Si cuboids that sustain bound states in the continuum enable the injection of dense electron-hole plasma and provide high quantum efficiency.