Ultrafast Silicon Photonics with Visible to Mid-Infrared Pumping of Silicon Nanocrystals

Benjamin T. Diroll, Katelyn S. Schramke, Peijun Guo, Uwe R. Kortshagen, Richard D Schaller

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Dynamic optical control of infrared (IR) transparency and refractive index is achieved using boron-doped silicon nanocrystals excited with mid-IR optical pulses. Unlike previous silicon-based optical switches, large changes in transmittance are achieved without a fabricated structure by exploiting strong light coupling of the localized surface plasmon resonance (LSPR) produced from free holes of p-Type silicon nanocrystals. The choice of optical excitation wavelength allows for selectivity between hole heating and carrier generation through intraband or interband photoexcitation, respectively. Mid-IR optical pumping heats the free holes of p-Si nanocrystals to effective temperatures greater than 3500 K. Increases of the hole effective mass at high effective hole temperatures lead to a subpicosecond change of the dielectric function, resulting in a redshift of the LSPR, modulating mid-IR transmission by as much as 27%, and increasing the index of refraction by more than 0.1 in the mid-IR. Low hole heat capacity dictates subpicosecond hole cooling, substantially faster than carrier recombination, and negligible heating of the Si lattice, permitting mid-IR optical switching at terahertz repetition frequencies. Further, the energetic distribution of holes at high effective temperatures partially reverses the Burstein-Moss effect, permitting the modulation of transmittance at telecommunications wavelengths. The results presented here show that doped silicon, particularly in micro-or nanostructures, is a promising dynamic metamaterial for ultrafast IR photonics.

Original languageEnglish
Pages (from-to)6409-6414
Number of pages6
JournalNano Letters
Volume17
Issue number10
DOIs
Publication statusPublished - Oct 11 2017

Keywords

  • doping
  • infrared
  • optical switching
  • plasmonics
  • Silicon photonics

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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