Optical Modulation via Guided-Mode Resonance in an ITO-Loaded Distributed Bragg Reflector Topped With a Two-Dimensional Grating

Vatani, Sare; Taleb, Hussein; Moravvej-Farshi, Mohammad Kazem

doi:10.1109/jstqe.2021.3055736

Cited by 16 publications

(6 citation statements)

References 20 publications

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“…It is worth mentioning that this nearly perfect (99.2%) absorption is due to the appropriately engineered Si metasurfaces satisfying the critical coupling condition at λ = 1310 nm. Moreover, any deviation in the metasurface geometry from the dimensions given in Table 1 , alters the narrow linewidth at 1310 nm 43 . The linewidth of the reflectance in the OFF state indicates the device quality factor Q > 10,000.…”

Section: Resultsmentioning

confidence: 99%

“…In this mechanism, the energy consumption will be about a few fJ/bits, but RC delay is the limiting factor for modulation speed. Energy consumption and modulation speed are both the primary figures of merits 43 . However, all-optical modulators are excellent options for reaching ultrafast modulation 30 .…”

Section: Introductionmentioning

confidence: 99%

“…The metasurface consists of a 2D array of cubic Si gratings patterned on top of the structure, coupling the incident light as a guided-mode resonance (GMR). We have optimized its geometry that highly affects the GMR wavelength according to the procedure we have already described elsewhere 43 to achieve the critical coupling condition for maximum absorption and minimum reflection at λ = 1310 nm in the modulator OFF state. In other words, when the pump pulse is OFF, the reflectivity at 1310 nm drops to near zero, but in the presence of a pump pulse, it becomes more than 0.9.…”

Section: Introductionmentioning

confidence: 99%

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All-optical AZO-based modulator topped with Si metasurfaces

Vatani

Barahimi

Moravvej-Farshi

2022

Sci Rep

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All-optical communication systems are under continuous development to address different core elements of inconvenience. Here, we numerically investigate an all-optical modulator, realizing a highly efficient modulation depth of 22 dB and a low insertion loss of 0.32 dB. The tunable optical element of the proposed modulator is a layer of Al-doped Zinc Oxide (AZO), also known as an epsilon-near-zero transparent conductive oxide. Sandwiching the AZO layer between a carefully designed distributed Bragg reflector and a dielectric metasurface—i.e., composed of a two-dimensional periodic array of cubic Si—provides a guided-mode resonance at the OFF state of the modulator, preventing the incident signal reflection at λ = 1310 nm. We demonstrate the required pump fluence for switching between the ON/OFF states of the designed modulator is about a few milli-Joules per cm2. The unique properties of the AZO layer, along with the engineered dielectric metasurface above it, change the reflection from 1 to 93%, helping design better experimental configurations for the next-generation all-optical communication systems.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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All-optical AZO-based modulator topped with Si metasurfaces

Vatani

Barahimi

Moravvej-Farshi

2022

Sci Rep

Self Cite

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“…In particular, electrical gating, optical pumping, thermal annealing, and current-induced heating can be employed for this purpose 14 – 19 Thus far, quantum-confined Stark effects in multiple quantum wells, 20 , 21 molecular phase transitions in vanadium dioxide (VO2) or germanium antimony telluride, 22 reorientation of molecules in liquid crystals, 23 ionic transparent, and carrier-induced field effects in semiconductors, i.e., silicon (Si), gallium arsenide, 24 , 25 transparent conducting oxides (TCOs), 26 – 30 indium arsenide (InAs), 31 , 32 and atomically thin transition metal dichalcogenides, 33 , 34 have been leveraged for index modulation. Among these tuning mechanisms, the free-carrier-induced effects in doped semiconductors have yielded great promise for active tuning thanks to higher modulation frequencies (up to several gigahertz), continuous tunability, and lower power consumption compared to techniques based on the Pockels effect or waveguide modulators based on lithium niobate.…”

Section: Introductionmentioning

confidence: 99%

High-quality-factor space–time metasurface for free-space power isolation at near-infrared regime

Sabri,

Mosallaei

2023

Adv. Photon. Nexus

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.Space–time metasurfaces are promising candidates for breaking Lorentz reciprocity, which constrains light propagation in numerous practical applications. There is a substantial difference between carrier and modulation frequencies in space–time photonic metasurfaces that leads to negligible spatial pathway variation of light and weak nonreciprocal response. To surmount this obstacle, herein, the design principle of a high-quality-factor space–time gradient metasurface is demonstrated at the near-infrared regime that increases the lifetime of photons and allows for strong power isolation by lifting the adiabaticity of modulation. The all-dielectric metasurface consists of an array of silicon subwavelength gratings (SWGs) that are separated from distributed Bragg reflectors by a silica buffer. The resonant mode with ultrahigh quality-factor exceeding 104 is excited within the SWG, which is characterized as magnetic octupole and features strong field localization. The SWGs are configured as multijunction p–n layers, whose multigate biasing with time-varying waveforms enables modulation of carriers in space and time. The proposed nonreciprocal metasurface is exploited for free-space optical power isolation by virtue of modulation-induced phase shift. It is shown that under time reversal and by interchanging the directions of incident and observation ports, power isolation of ≈35 dB can be maintained between the two ports in free space.

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“…However, such optical modulators suffer from large device footprints and low modulation efficiencies due to the low refractive index change induced by the injected carriers . Hence, it is highly desirable to employ other effective materials such as transparent conductive oxides, − liquid crystals, graphene, − and phase change materials − into the silicon platforms.…”

Section: Introductionmentioning

confidence: 99%

Design and Analysis of a Polarization-Insensitive VO₂/Graphene Optical Modulator Using a 3D Heat Transfer Method

Heidari

Bahadori-Haghighi

2022

ACS Appl. Electron. Mater.

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Phase change materials like vanadium dioxide (VO 2 ) have recently gained particular attention to realize effective optical modulators. In this paper, we propose a high-performance optical modulator based on VO 2 . The structure is constructed by a stack of two graphene sheets spaced by a VO 2 layer that are all grown over a silicon waveguide. The input light propagating along the modulating region of the waveguide can interact with the VO 2 at the top and side of the structure. When an external voltage is applied across the graphene sheets, the VO 2 changes to the metallic phase and the modulator is set at the off state. Most of the previously reported VO 2 -based modulators are polarization sensitive and suffer from high polarization diversity. When such modulators are integrated into a fiber-based optical system containing light with random polarization, the modulation efficiency is profoundly degraded. In our proposed modulator, the structure is optimized to achieve a polarization-insensitive response with an off-state propagation loss of ∼14 dB/μm. The TE (TM) insertion loss is also calculated to be as low as 2.25 dB/μm (3.22 dB/μm), so that an extinction ratio of as high as ∼11.5 dB/μm is obtained. In addition, the required low modulating voltage of 1.12 V and reasonable modulation speed of 390 MHz together with the low energy consumption of 2.1 fJ/bit could make our proposed modulator a good candidate for photonic integrated systems.

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Optical Modulation via Guided-Mode Resonance in an ITO-Loaded Distributed Bragg Reflector Topped With a Two-Dimensional Grating

Cited by 16 publications

References 20 publications

All-optical AZO-based modulator topped with Si metasurfaces

All-optical AZO-based modulator topped with Si metasurfaces

High-quality-factor space–time metasurface for free-space power isolation at near-infrared regime

Design and Analysis of a Polarization-Insensitive VO₂/Graphene Optical Modulator Using a 3D Heat Transfer Method

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Optical Modulation via Guided-Mode Resonance in an ITO-Loaded Distributed Bragg Reflector Topped With a Two-Dimensional Grating

Cited by 16 publications

References 20 publications

All-optical AZO-based modulator topped with Si metasurfaces

All-optical AZO-based modulator topped with Si metasurfaces

High-quality-factor space–time metasurface for free-space power isolation at near-infrared regime

Design and Analysis of a Polarization-Insensitive VO2/Graphene Optical Modulator Using a 3D Heat Transfer Method

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Product

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About

Design and Analysis of a Polarization-Insensitive VO₂/Graphene Optical Modulator Using a 3D Heat Transfer Method