Fabrication and characterization of three-dimensional copper metallodielectric photonic crystals

Amir Tal,Raymond C Rumpf,Stephen M Kuebler,Henry E Williams,Yun-Sheng Chen

doi:10.1364/oe.15.018283

Amir Tal, Raymond C Rumpf + Show 3 more

Open Access

https://doi.org/10.1364/oe.15.018283

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Journal: Optics Express	Publication Date: Jan 1, 2007
Citations: 38	License type: cc-by

Affiliation: University of Central Florida

Abstract

Three-dimensional metallodielectric photonic crystals were created by fabricating a micron-scale polymeric template using multiphoton direct laser writing (DLW) in SU-8 and conformally and selectively coating the template with copper (Cu) via nanoparticle-nucleated electroless metallization. This process deposits a uniform metal coating, even deep within a lattice, because it is not directional like sputter-coating or evaporative deposition. Infrared reflectance spectra show that upon metallization the optical behavior transitions fully from a dielectric photonic crystal to that of a metal photonic crystal (MPC). After depositing 50 nm of Cu, the MPCs exhibit a strong plasmonic stop band having reflectance greater than 80% across the measured part of the band and reaching as high as 95% at some wavelengths. Numerical simulations match remarkably well with the experimental data and predict all dominant features observed in the reflectance measurements, showing that the MPCs are structurally well formed. These data show that the Cu-based process can be used to create high performance MPCs and devices that are difficult or impossible to fabricate by other means.

Highlights

Three-dimensional (3D) metal photonic crystals (MPCs) can exhibit intriguing electromagnetic properties such as ultra-wide photonic [1,2,3,4,5] or “plasmonic” [6,7,8] band gaps, selectively tailored thermal emission [9,10,11], extrinsically modified absorption [4], and negative refractive index [12]
Three-dimensional metallodielectric photonic crystals were created by fabricating a micron-scale polymeric template using multiphoton direct laser writing (DLW) in SU-8 and conformally and selectively coating the template with copper (Cu) via nanoparticle-nucleated electroless metallization
Optical wavelength MPCs have been created using planar semiconductor fabrication techniques coupled with vapor- and liquid-phase metallization [4,9]; sputtering gold (Au) or electro-plating nickel (Ni) onto polymeric photonic crystals (PCs) created by soft-lithography [5]; and infiltrating selfassembled PCs with metal [13,14]

Summary

Introduction

Three-dimensional (3D) metal photonic crystals (MPCs) can exhibit intriguing electromagnetic properties such as ultra-wide photonic [1,2,3,4,5] or “plasmonic” [6,7,8] band gaps, selectively tailored thermal emission [9,10,11], extrinsically modified absorption [4], and negative refractive index [12]. We demonstrate that the process selectively deposits Cu onto the SU-8 pre-form leaving the supporting substrate unmetallized This feature makes the present method satisfactory for creating functional devices and integrated photonic structures, unlike non-selective routes [20]. We provide insight into how the optical properties change during metallization and how the process can be used to achieve targeted metallodielectric properties The latter point is significant in that optical fabrication processes cannot become widely applied until there is deep understanding of how the properties and performance relate to the processing conditions and the resulting micro- and nano-scale structure

Experimental

Metallization process

Photonic crystal fabrication

Photonic crystal characterization

Numerical simulation

Conclusion