Extremely sub-wavelength THz metal-dielectric wire microcavities

Feuillet-Palma, C.; Todorov, Yanko; Steed, Robert; Vasanelli, Angela; Biasiol, G.; Sorba, L.; Sirtori, Carlo

doi:10.1364/oe.20.029121

Cited by 36 publications

(48 citation statements)

References 24 publications

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“…We define G= E d1 / E d2 as the enhancement factor of the energy density. A cavity with too big or small volume will affect the electromagnetic (EM) energy absorption and confinement inside the cavity [23]. Only when the parameters of the material and geometry are optimized, the impedance of the structure matching to the impedance of vacuum will the extreme confinement of the EM field and strong absorption inside the cavities appear.…”

Section: Localizing Featuresmentioning

confidence: 99%

“…In particular, the ohmic loss is very low in the far infrared region, where it has a perfect reflection characteristic. Because of these features, we can break the diffraction limitation and confine light within a sub-wavelength volume [23]. So far, confining light within a sub-wavelength volume has become one of the hot issues in the optical metamaterial research.…”

Section: Introductionmentioning

confidence: 99%

“…So far, confining light within a sub-wavelength volume has become one of the hot issues in the optical metamaterial research. In the terahertz region, dimensions can be reduced to extreme subwavelength [23,24]. Furthermore, Fevillet-Palma et al [25] studied the near-field enhancement properties of the antenna in the terahertz region and originally calculated the electromagnetic energy density in the cavities.…”

Section: Introductionmentioning

confidence: 99%

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Electromagnetic resonant properties of metal-dielectric-metal (MDM) cylindrical microcavities

Heng

Wang

2017

Photonic Sens

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Optical metamaterials can concentrate light into extremely tiny volumes to enhance their interaction with quantum objects. In this paper, a cylindrical microcavity based on the Au-dielectric-Au sandwiched structure is proposed. Numerical study shows that the cylindrical microcavity has the strong ability of localizing light and confining 10 3 --10 4 -fold enhancement of the electromagnetic energy density, which contains the most energy of the incoming light. The enhancement factor of energy density G inside the cavity shows the regularities as the change in the thickness of the dielectric slab, dielectric constant, and the radius of gold disk. At the normal incidence of electromagnetic radiation, the obtained reflection spectra operate in the range from 4.8 μm to 6 μm and with the absorption efficiency C (C=1-R min ), which can reach 99% by optimizing the structure's geometry parameters, and the dielectric constant. Due to the symmetry of the cylindrical microcavities, this structure is insensitive to the polarization of the incident wave. The proposed optical metamaterials will have potential applications in the surface enhanced spectroscopy, new plasmonic detectors, bio-sensing, solar cells, etc.

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Section: Localizing Featuresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electromagnetic resonant properties of metal-dielectric-metal (MDM) cylindrical microcavities

Heng

Wang

2017

Photonic Sens

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“…2 Similarly, Purcell enhancement of spontaneous emission has been observed in LC microresonators as well as mirror-grating metal cavities 3,4 and microcavity effects for THz quantum cascade lasers have been discussed. 5,6 Double-metal confinement lends itself to the creation of arrays of patch antenna microcavities and has led to the demonstration of the ultra-strong lightmatter coupling regime and the realization of efficient infrared and THz detectors.…”

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confidence: 92%

Patch antenna microcavity terahertz sources with enhanced emission

Madéo

Todorov

Gilman

et al. 2016

Applied Physics Letters

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We study the emission properties of an electroluminescent THz frequency quantum cascade structure embedded in an array of patch antenna double-metal microcavities. We show that high photon extraction efficiencies can be obtained by adjusting the active region thickness and array periodicity as well as high Purcell factors (up to 65), leading to an enhanced overall emitted power. Up to a 44-fold increase in power is experimentally observed in comparison with a reference device processed in conventional mesa geometry. Estimation of the Purcell factors using electromagnetic simulations and the theoretical extraction efficiency are in agreement with the observed power enhancement and show that, in these microcavities, the overall enhancement solely depends on the square of the total quality factor. Published by AIP Publishing. The ability to realize efficient sources and detectors at terahertz (THz) frequencies is of importance as this opens the way to a wide range of potential applications in molecular spectroscopy, imaging, security scanning, and in the fundamental studies of low energy chemical and physical processes.1 For optoelectronic devices operating in the THz range, the light-matter interaction can be significantly enhanced by confining the electromagnetic field into highly sub-wavelength metallic structures. Effective volumes as low as 10, where k is the radiation wavelength, have been achieved in passive double-metal micro-cavities comprising a dielectric layer bounded by a metallic back-plane and a patterned top metal layer.2 Similarly, Purcell enhancement of spontaneous emission has been observed in LC microresonators as well as mirror-grating metal cavities 3,4 and microcavity effects for THz quantum cascade lasers have been discussed. 5,6 Double-metal confinement lends itself to the creation of arrays of patch antenna microcavities and has led to the demonstration of the ultra-strong lightmatter coupling regime and the realization of efficient infrared and THz detectors. [7][8][9] In the case of square resonators, the resonant wavelength, k, is set by the length of the square side, s, through the formula s ¼ k/2n eff, where n eff is the effective mode index. This photonic structure is ideal for intersubband (ISB) emitters as the oscillating dipoles of the electronic transition align with the intracavity TM mode polarization. In addition, this geometry behaves as a patch antenna, rotating the polarization of the confined field by 90 when radiating into the far-field. Therefore, one can realize surface emitting photonic devices in which the light-matter interaction can be enhanced by resonantly tuning the energy of the microcavity mode with a radiative ISB transition by adjusting only the geometric parameter s. 10In this letter, we study THz frequency emission from arrays of double-metal patch microcavities containing a quantum cascade (QC) active region. We demonstrate the enhancement of the electroluminescence owing to an efficient out-coupling that is achieved by carefully choosing the thickness of ...

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“…Strong light-matter interaction between planar MSs and ISTs in QWs is easily scalable throughout the infrared spectrum and occurs on a single resonator level involving only a small number of electrons [21]. Previous papers using other subwavelength geometries that include metallic backplanes have shown strong coupling at the single resonator level and/or a small number of carriers involved in the process [22][23][24]. We remark that such a backplane is not required to achieve subwavelength volumes as demonstrated recently in [21] or in this paper.…”

Section: Introductionmentioning

confidence: 99%

Electrodynamic modeling of strong coupling between a metasurface and intersubband transitions in quantum wells

et al. 2014

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Strong light-matter coupling has recently been demonstrated in subwavelength volumes by coupling engineered optical transitions in semiconductor heterostructures (e.g., quantum wells) to metasurface resonances via near fields. It has also been shown that different resonator shapes may lead to different Rabi splittings, though this has not yet been well explained. In this paper, our aim is to understand the correlation between resonator shape and Rabi splitting, in particular to determine and quantify the physical parameters that affect strong coupling by developing an equivalent circuit network model whose elements describe energy and dissipation. Because of the subwavelength dimension of each metasurface element, we resort to the quasistatic (electrostatic) description of the near field and hence define an equivalent capacitance associated to each dipolar element of a flat metasurface. We show that this is also able to accurately model the phenomenology involved in strong coupling between the metasurface and the intersubband transitions in quantum wells. We show that the spectral properties and stored energy of a metasurface/quantum-well system obtained using our model are in good agreement with both full-wave simulation and experimental results. We then analyze metasurfaces made of three resonator geometries and observe that the magnitude of the Rabi splitting increases with the resonator capacitance in agreement with our theory, providing a phenomenological explanation for the resonator shape dependence of the strong coupling process.

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Extremely sub-wavelength THz metal-dielectric wire microcavities

Cited by 36 publications

References 24 publications

Electromagnetic resonant properties of metal-dielectric-metal (MDM) cylindrical microcavities

Electromagnetic resonant properties of metal-dielectric-metal (MDM) cylindrical microcavities

Patch antenna microcavity terahertz sources with enhanced emission

Electrodynamic modeling of strong coupling between a metasurface and intersubband transitions in quantum wells

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