Electrically tunable perfect light absorbers as color filters and modulators

Abstract

Methods for spectrally controlling light absorption in optoelectronic devices have attracted considerable attention in recent years. It is now well known that a Fabry-Perot nanocavity comprising thin semiconductor and metal films can be used to absorb light at selected wavelengths. The absorption wavelength is controlled by tailoring the thickness of the nanocavity and also by nanostructure patterning. However, the realization of dynamically tuning the absorption wavelength without changing the structural geometry remains a great challenge in optoelectronic device development. Here it is shown how an ultrathin n-type doped indium antimonide integrated into a subwavelengththick optical nanocavity can result in an electrically tunable perfect light absorber in the visible and near infrared range. These absorbers require simple thin-film fabrication processes and are cost effective for large-area devices without resorting to sophisticated nanopatterning techniques. In the visible range, a 40 nm spectral shift can be attained by applying a reasonable bias voltage to effect the color change. It is also shown that these electrically tunable absorbers may be used as optical modulators in the infrared. The predicted (up to) 95.3% change in reflectance, transforming the device from perfectly absorbing to highly reflective, should make this technology attractive to the telecommunication (switching) industry.Thin-film light absorbers have recently received considerable attention due to their straightforward fabrication, low cost, and wide range of potential applications, however they have been restricted to the near infrared range or they are not tunable, or they are not perfect absorbers. Tunable perfect light absorbers functioning in the visible range as discussed in this paper comprise a Fabry-Perot nanocavity made of thin metal and semiconductor films that absorb light completely over selected wavelength ranges in the visible and infrared. The fundamental absorption wavelength is determined by the thickness of the nanocavity and tunability is bias voltage controlled. This newest generation of perfect light absorbers would have many interdisciplinary applications in chemical and biological sensing 1-7 , solar energy harvesting 8-11 , photodetectors 12,13 , gas sensors 14 , structural color printing [15][16][17][18] , and color filters [19][20][21][22][23][24][25][26] . However, if the absorption could be controlled in real time, then multiple new applications can be envisioned such as high speed, high resolution, high grey scale displays, smart windows, and a variety of telecommunication devices to compete with those currently available. To ascertain the possibilities, a theoretical investigation into ultrathin spectrally selective perfect light absorption in a nanocavity structure made of an epsilon-near-zero (ENZ) material (as the active layer) is summarized here. The metal/ENZ/dielectric/metal structure is modeled as a nanocavity, allowing the enhancement of light absorption at the resonant wavelength to be explored....

Impact of Cubic Symmetry on Optical Activity of Dielectric 8-srs Networks

“…OA through a gas filled interaction volume serves as a sensing signal for determination of gas composition or concentration. Moreover, thickness, PSB, and OA are crucial prerequisites for many ultra-thin optical devices such as optical filters [39][40][41] and polarization rotators [42,43].…”

Active metamaterial nearly perfect light absorbers: a review [Invited]

“…As the key materials for the fabrication of electronics and photonics devices, semiconductors have the capability of having tunable electronic and optical responses. Recently, there have been numerous reports on using optically [71,159,[160][161][162] and electrically tunable [156][157][158] semiconductors in obtaining active metamaterials and active PMAs. Figure 3(e) shows a schematic of a InAs-based plasmonic metasurface that acts as an active thermal emitter within 4 to 10 μm.…”

“…As another example, Fig. 3(f) shows how an ultrathin n-type doped indium antimonide integrated into a subwavelength thick optical nanocavity can result in an electrically tunable perfect light absorber in the visible and near infrared ranges [157]. This structure may also be used as the optical modulators in the NIR.…”

Strong Interference in Planar, Multilayer Perfect Absorbers: Achieving High-Operational Performances in Visible and Near-Infrared Regimes

“…Several different MI pair combinations have been employed to obtain high-efficiency color filters [19], [20], [22], [43], [97]. One of the main challenges of these MIM color filters is their angle-sensitive response.…”