Integrated Optical Modulator Based on Transition between Photonic Bands

Gövdeli, Alperen; Sarihan, Murat Can; Karaca, Utku; Kocaman, Serdar

doi:10.1038/s41598-018-20097-7

Cited by 27 publications

(21 citation statements)

References 69 publications

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“…Consequently, even a slight inhomogeneity leads to an undesired refractive‐index nonuniformity in the intrinsic region. Our observations are consistent with the experimental results of Soref and Bennett, [ 61,62 ] and several relevant published works based on the P–I–N principles with carrier density injection of 4 × 10 17 cm −3 , [ 37 ] 4.1 × 10 18 cm −3 , [ 40 ] 1 × 10 19 cm −3 , [ 41 ] 10 18 –10 19 cm −3 , [ 42 ] and 2.93 × 10 19 cm −3 . [ 63 ]…”

Section: Resultssupporting

confidence: 93%

A Tunable Semiconductor‐Based Transmissive Metasurface: Dynamic Phase Control with High Transmission Level

Forouzmand

Mosallaei

2020

Laser & Photonics Reviews

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Herein, a tunable semiconductor‐based metasurface, based on electro‐optical modulation of an array of geometrically‐fixed silicon (Si) nanobars, sandwiched between two distributed Bragg reflectors (DBRs) is proposed. A flat‐top transmission spectrum with a steep phase profile, which turns out to be essential to realize a highly‐efficient spatial light modulator in transmission mode, is formed by excitation of two spectrally close Fabry‐Pérot‐type and guided‐mode resonances. The refractive‐index of Si nanobars is electrically modulated by the injection of electrons and holes using a P–I–N junction configuration, considered along each nanobar. It is theoretically demonstrated that wide phase agility of 215° and transmission amplitude higher than 0.6 (with an average of ≈0.83) can be accomplished at the operating wavelength of ≈1.55 µm. This wide‐range tunability is realized by introducing free electron and hole carrier densities of ∆N = ∆P = 5 × 1018 cm−3 accompanied with Si refractive‐index‐change of ∆nSi = 0.01. The transmission phase of each unit cell can be separately controlled, which in turn allows to design a tunable meta‐array with real‐time beam control. As a proof of concept, a dynamic focusing metalens with an adjustable focal length is designed and numerically investigated.

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Section: Resultssupporting

confidence: 93%

A Tunable Semiconductor‐Based Transmissive Metasurface: Dynamic Phase Control with High Transmission Level

Forouzmand

Mosallaei

2020

Laser & Photonics Reviews

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“…The modulation bandwidth is inversely proportional to the device footprint area. Implementing the device with a compact footprint, it is feasible to achieve modulation bandwidths larger than the optical bandwidth of resonances which is critical for achieving a high depth in optical signal modulation . Considering a lateral extent of 15 µm along the axis of nanobars for the proposed structure, the RC time constant is estimated τ RC = RC < 15 ps from device simulations when the applied bias voltage exceeds 0.5 V which yields a maximal modulation frequency of f m = 1/2 πτ RC > 10 GHz.…”

Section: Time‐modulated Metasurfacementioning

confidence: 99%

“…Considering that the modulation of carrier concentrations in the range of 10 16 –10 19 cm −3 across the intrinsic region requires bias voltage varying in the range of 0.75–1.75 V, modulation frequencies over 10 GHz can be achieved. We should emphasize that the bias voltage should exceed 0.5 V for attaining modulation frequencies over 10 GHz due to the high resistivity of p‐i‐n junction at low injection levels . Considering that the speed of on‐chip RF interconnects allow for modulation frequencies up to 100 GHz, a stable time‐modulated metasurface can be realized by applying radio‐frequency biasing signals for the elements.…”

Section: Time‐modulated Metasurfacementioning

confidence: 99%

A Dynamically Modulated All‐Dielectric Metasurface Doublet for Directional Harmonic Generation and Manipulation in Transmission

Salary

Farazi

Mosallaei

2019

Advanced Optical Materials

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metasurface to achieve a certain functionality in reflection or transmission mode. Recent years have witnessed the development of phase-gradient metasurfaces with different configurations for a wide range of applications such as beam-steering, focusing, and holography. [1,2] These structures allow for integration of various functionalities into a flat surface thus leading to a dramatic reduction in the footprint of optical systems by replacing conventional bulky optical components.Spatiotemporal control over the phase of transmitted and reflected lights across the 2π span is the key to achieve the desired functionalities. The phase tuning mechanisms of metasurfaces have been mostly based on varying the size of nanoantennas within the resonant scattering regime or rotating half-wave plate elements to imprint a geometric phase shift on the circularly polarized light scattered with the opposite handedness. [3,4] For a nanoantenna supporting a single isolated electric or magnetic resonance, the maximal resonant phase agility is π which hinders full control over the light wavefront without employing a back mirror. Metasurfaces with both electric and magnetic responses can be used to overcome this limitation via spectrally overlapping [5] and interleaving [6] electric and magnetic resonances for operation in transmission and reflection modes, respectively. The spectral overlap of electric and magnetic dipole resonances in a Huygens' metasurface satisfies the first Kerker condition leading to suppressed backward scattering from the elements thus eliminating the reflection and giving rise to maximal transmission with 2π phase agility. Although Huygens' metasurfaces have been constructed using metallic elements in microwave regime, bringing plasmonic Huygens' metasurfaces into optical frequencies is challenging due to their complex geometries and arrangements, and is further hindered by the significant increase in the ohmic loss of plasmonic materials at higher frequencies. [7] All-dielectric metasurfaces consisted of high-index subwavelength elements embedded in a low-index environment can eliminate these limitations in that they can support both electric and magnetic resonances with simple geometries and do not suffer from significant dissipative losses. [8][9][10] Moreover, they are fully compatible with standard In this paper, an electrically tunable all-dielectric metasurface doublet is proposed operating at mid-infrared frequency regime with dynamic 2π phase span in transmission mode. Each layer of the metasurface consists of a periodic array of silicon nanobars configured into p-i-n junctions in which the double carrier injection into the intrinsic region under forward bias allows for tuning of the silicon refractive index. The physical mechanism is based on the spectral overlap of high quality factor guided mode resonances supported by each constituent layer establishing an extreme Huygens' operation regime of nearly reflectionless transmission with steep phase spectrum. The short response time of field-driven car...

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“…One of the useful techniques to realize the phase shifters is using Photonic Crystal (PC) metamaterials. It is represented that PC metamaterials can tune the photonic dispersion so that one can build new optical devices with new functionalities [3,4,8,[10][11][12][13][14][15][16][17]. In fact, PC metamaterials could be built in a way which exhibit Dirac-cone photonic dispersion in the center of Brillouin-Zone in an arbitrary frequency using the concept of accidental degeneracy [15].…”

Section: Introductionmentioning

confidence: 99%

Total phase shift of terahertz wave in a rectangular waveguide with zero-refractive index metamaterial

Ghaffari

Zandi

2020

J. Phys. Commun.

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In many applications, appropriate spatial phase shifts in propagation of a THz wave are desired. Serving this purpose, a rectangular waveguide with two-dimensional photonic crystal zero-refractive index metamaterial is studied. In this structure, additional phase shift is computed in a numerical method in comparison with the same waveguide without zero-refractive index metamaterial. Modelling the characteristics of this waveguide, relations are presented which are shown to be compatible with numerical results. Then getting in inverse direction, a procedure is introduced in which, equivalent photonic crystals can be designed in terms of an arbitrary given phase shift with estimated errors of less than 1 degree. We also have calculated the sensitivity of additional phase difference with respect to the refractive index of rods, which showed relatively high dependence.

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Integrated Optical Modulator Based on Transition between Photonic Bands

Cited by 27 publications

References 69 publications

A Tunable Semiconductor‐Based Transmissive Metasurface: Dynamic Phase Control with High Transmission Level

A Tunable Semiconductor‐Based Transmissive Metasurface: Dynamic Phase Control with High Transmission Level

A Dynamically Modulated All‐Dielectric Metasurface Doublet for Directional Harmonic Generation and Manipulation in Transmission

Total phase shift of terahertz wave in a rectangular waveguide with zero-refractive index metamaterial

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