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Title: Porous Silicon Gradient Refractive Index Micro-Optics

Abstract

We see the emergence and growth of transformation optics over the past decade has revitalized interest in how a gradient refractive index (GRIN) can be used to control light propagation. Two-dimensional demonstrations with lithographically defined silicon (Si) have displayed the power of GRIN optics and also represent a promising opportunity for integrating compact optical elements within Si photonic integrated circuits. Here, we demonstrate the fabrication of three-dimensional Si-based GRIN micro-optics through the shape-defined formation of porous Si (PSi). Conventional microfabrication creates Si square microcolumns (SMCs) that can be electrochemically etched into PSi elements with nanoscale porosity along the shape-defined etching pathway, which imparts the geometry with structural birefringence. Free-space characterization of the transmitted intensity distribution through a homogeneously etched PSi SMC exhibits polarization splitting behavior resembling that of dielectric metasurfaces that require considerably more laborious fabrication. Coupled birefringence/GRIN effects are studied by way of PSi SMCs etched with a linear (increasing from edge to center) GRIN profile. The transmitted intensity distribution shows polarization-selective focusing behavior with one polarization focused to a diffraction-limited spot and the orthogonal polarization focused into two laterally displaced foci. Optical thickness-based analysis readily predicts the experimentally observed phenomena, which strongly match finite-element electromagnetic simulations.

Authors:
 [1];  [2];  [1];  [1];  [3];  [4];  [1];  [2];  [1]
  1. Univ. of Illinois at Urbana-Champaign, IL (United States). Beckman Inst. for Advanced Science and Technology
  2. Stanford Univ., CA (United States). Geballe Lab. for Advanced Materials
  3. Dow Chemical Co., Freeport, TX (United States)
  4. Department of Mechanical Science and Engineering, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Light-Material Interactions in Energy Conversion (LMI)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
OSTI Identifier:
1388664
Grant/Contract Number:  
SC0001293
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Nano Letters
Additional Journal Information:
Journal Volume: 16; Journal Issue: 12; Related Information: LMI partners with California Institute of Technology (lead); Harvard University; University of Illinois, Urbana-Champaign; Lawrence Berkeley National Laboratory; Journal ID: ISSN 1530-6984
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; solar (photovoltaic), solid state lighting, phonons, thermal conductivity, electrodes - solar, materials and chemistry by design, optics, synthesis (novel materials), synthesis (self-assembly)

Citation Formats

Krueger, Neil A., Holsteen, Aaron L., Kang, Seung-Kyun, Ocier, Christian R., Zhou, Weijun, Mensing, Glennys, Rogers, John A., Brongersma, Mark L., and Braun, Paul V. Porous Silicon Gradient Refractive Index Micro-Optics. United States: N. p., 2016. Web. doi:10.1021/acs.nanolett.6b02939.
Krueger, Neil A., Holsteen, Aaron L., Kang, Seung-Kyun, Ocier, Christian R., Zhou, Weijun, Mensing, Glennys, Rogers, John A., Brongersma, Mark L., & Braun, Paul V. Porous Silicon Gradient Refractive Index Micro-Optics. United States. https://doi.org/10.1021/acs.nanolett.6b02939
Krueger, Neil A., Holsteen, Aaron L., Kang, Seung-Kyun, Ocier, Christian R., Zhou, Weijun, Mensing, Glennys, Rogers, John A., Brongersma, Mark L., and Braun, Paul V. 2016. "Porous Silicon Gradient Refractive Index Micro-Optics". United States. https://doi.org/10.1021/acs.nanolett.6b02939. https://www.osti.gov/servlets/purl/1388664.
@article{osti_1388664,
title = {Porous Silicon Gradient Refractive Index Micro-Optics},
author = {Krueger, Neil A. and Holsteen, Aaron L. and Kang, Seung-Kyun and Ocier, Christian R. and Zhou, Weijun and Mensing, Glennys and Rogers, John A. and Brongersma, Mark L. and Braun, Paul V.},
abstractNote = {We see the emergence and growth of transformation optics over the past decade has revitalized interest in how a gradient refractive index (GRIN) can be used to control light propagation. Two-dimensional demonstrations with lithographically defined silicon (Si) have displayed the power of GRIN optics and also represent a promising opportunity for integrating compact optical elements within Si photonic integrated circuits. Here, we demonstrate the fabrication of three-dimensional Si-based GRIN micro-optics through the shape-defined formation of porous Si (PSi). Conventional microfabrication creates Si square microcolumns (SMCs) that can be electrochemically etched into PSi elements with nanoscale porosity along the shape-defined etching pathway, which imparts the geometry with structural birefringence. Free-space characterization of the transmitted intensity distribution through a homogeneously etched PSi SMC exhibits polarization splitting behavior resembling that of dielectric metasurfaces that require considerably more laborious fabrication. Coupled birefringence/GRIN effects are studied by way of PSi SMCs etched with a linear (increasing from edge to center) GRIN profile. The transmitted intensity distribution shows polarization-selective focusing behavior with one polarization focused to a diffraction-limited spot and the orthogonal polarization focused into two laterally displaced foci. Optical thickness-based analysis readily predicts the experimentally observed phenomena, which strongly match finite-element electromagnetic simulations.},
doi = {10.1021/acs.nanolett.6b02939},
url = {https://www.osti.gov/biblio/1388664}, journal = {Nano Letters},
issn = {1530-6984},
number = 12,
volume = 16,
place = {United States},
year = {Mon Nov 07 00:00:00 EST 2016},
month = {Mon Nov 07 00:00:00 EST 2016}
}

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Cited by: 22 works
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