All-Semiconductor Negative-Index Plasmonic Absorbers

Abstract

We demonstrate epitaxially grown all-semiconductor thin-film midinfrared plasmonic absorbers and show that absorption in these structures is linked to the excitation of highly confined negative-index surface plasmon polaritons. Strong (>98%) absorption is experimentally observed, and the spectral position and intensity of the absorption resonances are studied by reflection and transmission spectroscopy. Numerical models as well as an analytical description of the excited guided modes in our structures are presented, showing agreement with experiment. The structures investigated demonstrate a wavelength-flexible, all-semiconductor, plasmonic architecture with potential for both sensing applications and enhanced interaction of midinfrared radiation with integrated semiconductor optoelectronic elements.

Review of mid-infrared plasmonic materials

“…For this reason, there is a growing interest for mid-IR applications in materials with longer plasma wavelengths. For III-V optoelectronics, this would suggest the use of III-V doped semiconductors, which can be integrated directly into optoelectronic structures during epitaxial growth, and allow for device structures, 139 and even tuning schemes, 140 compatible with existing III-V optoelectronic architectures.…”

Electrically Reconfigurable Metasurfaces Using Heterojunction Resonators

“…Here, we use electromagnetics and device simulations to design electrically pumped semiconductor heterostructure resonators capable of arbitrarily tuning the refl ection phase of infrared light with little change in amplitude.Previous approaches for tuning metasurfaces-using metallic resonators coupled to an index tunable background [ 8,[23][24][25][26][27][28] or mechanically changing the shape of metallic resonators [ 5,29,30 ] have been unable to achieve reconfi gurable 2π phase shifts. This inability to achieve 2π phase control stems fundamentally from the nature of the underlying optical antennas.…”

“…Because the light-matter interaction lengths are subwavelength and the quality factors modest ( Q ≈ 1−10), very large refractive index modulation is needed (Δ n ≥ 1). InSb [31][32][33] or InAs [ 27,34,35 ] support free-carrier index shifts of this magnitude due to their high mobility and low electron effective mass. In our previous theory work, [ 36 ] we demonstrated full 2π tuning of the transmission phase of semiconductor metasurface by modulating the carrier concentration in InSb resonators between 10 17 -10 18 cm −3 .…”

Wideband ‘black silicon’ for mid-infrared applications

“…Among these materials, semiconductors have attracted great interest due to their well-established fabrication and integration technology. To date, various plasmonic and metamaterial absorbers have been studied with different semiconductors [12][13][14][15][16][17][18]. All-silicon efficient narrowband and broadband absorbers have been studied recently [19][20][21].…”