Parallel Directional Coupler based Dual-Polarization Electro-Absorption Modulator using Epsilon Near-Zero Material

2021 ◽  
Author(s):  
Tanmay Bhowmik ◽  
Debabrata Sikdar
Keyword(s):  
Indium Tin Oxide ◽  
High Speed ◽  
Directional Coupler ◽  
Modulation Depth ◽  
Extinction Ratio ◽  
Integrated Photonics ◽  
Dual Polarization ◽  
Active Length ◽  
Te Mode ◽  
Epsilon Near Zero

Abstract Electro–optical modulation, where a radio frequency signal can be encoded in an optical field, is crucial to decide the overall performance of an integrated photonics system. Due to the growing internet penetration rate worldwide, polarization-division-multiplexing (PDM) technique has emerged to increase the link capacity, where polarization-independent modulators are desirable to reduce system complexity. In this study, we propose a novel parallel directional coupler based dual-polarization electro-absorption modulator based on epsilon-near-zero (ENZ) material. The proposed design is capable of independent and synchronized modulation of two fundamental modes viz. transverse magnetic (TM) and transverse electric (TE) mode of a standard silicon rib waveguide. Indium-tin-oxide (ITO)–Silicon based two parallel hybrid plasmonic waveguides (HPW1 and HPW2) are placed such that fundamental TM (TE) mode of the input bus waveguide can be coupled to HPW1 (HPW2). The ENZ-state of ITO, acquired upon two independent electrical gating, enables large modulation depth by utilizing enhancement of electric field at the absorptive carrier accumulation layer. With a 27 μm active length, the extinction ratio (ER) of the proposed design is 10.11 dB (9.66 dB) for TM (TE) modulation at 1550 nm wavelength. This results in a 0.45 dB ER-discrepancy and indicates the polarization-insensitive nature of the modulator. The insertion losses and modulation bandwidths of our design are less than 1 dB and more than 100 GHz, respectively, for both polarizations over the entire C-band of wavelength. The proposed design can find potential applications in the PDM-enabled integrated photonics systems and high speed optical interconnections at data center networks.

scholarly journals A Broadband Polarization-Insensitive Graphene Modulator Based on Dual Built-in Orthogonal Slots Plasmonic Waveguide

2021 ◽  
Vol 11 (4) ◽  
pp. 1897
Author(s):  
Wei Chen ◽  
Yan Xu ◽  
Yang Gao ◽  
Lanjing Ji ◽  
Xibin Wang ◽  
...  
Keyword(s):  
High Speed ◽  
Transverse Electric ◽  
Modulation Depth ◽  
Transverse Magnetic ◽  
Plasmonic Effect ◽  
Te Mode ◽  
Tm Mode ◽  
Electro Optic ◽  
Polarization Insensitive ◽  
Electro Optic Modulator

A broadband polarization-insensitive graphene modulator has been proposed. The dual built-in orthogonal slots waveguide allows polarization independence for the transverse electric (TE) mode and the transverse magnetic (TM) mode. Due to the introduction of metal slots in both the vertical and horizontal directions, the optical field as well as the electro-absorption of graphene are enhanced by the plasmonic effect. The proposed electro-optic modulator shows a modulation depth of 0.474 and 0.462 dB/μm for two supported modes, respectively. An ultra-low effective index difference of 0.001 can be achieved within the wavelength range from 1100 to 1900 nm. The 3 dB-bandwidth is estimated to be 101 GHz. The power consumption is 271 fJ/bit at a modulation length of 20 μm. The proposed modulator provides high speed broadband solutions in microwave photonic systems.

scholarly journals Atto-Joule, high-speed, low-loss plasmonic modulator based on adiabatic coupled waveguides

Nanophotonics ◽  
2018 ◽  
Vol 7 (5) ◽  
pp. 859-864 ◽  
Author(s):  
Hamed Dalir ◽  
Farzad Mokhtari-Koushyar ◽  
Iman Zand ◽  
Elham Heidari ◽  
Xiaochuan Xu ◽  
...  
Keyword(s):  
High Speed ◽  
Modulation Depth ◽  
Extinction Ratio ◽  
Direct Result ◽  
Strongly Coupled ◽  
Optical Index ◽  
Phase Mismatching ◽  
Millimeter Wave Range ◽  
Modal Coupling ◽  
Waveguide System

AbstractIn atomic multi-level systems, adiabatic elimination (AE) is a method used to minimize complicity of the system by eliminating irrelevant and strongly coupled levels by detuning them from one another. Such a three-level system, for instance, can be mapped onto physically in the form of a three-waveguide system. Actively detuning the coupling strength between the respective waveguide modes allows modulating light to propagate through the device, as proposed here. The outer waveguides act as an effective two-photonic-mode system similar to ground and excited states of a three-level atomic system, while the center waveguide is partially plasmonic. In AE regime, the amplitude of the middle waveguide oscillates much faster when compared to the outer waveguides leading to a vanishing field build up. As a result, the plasmonic intermediate waveguide becomes a “dark state,” hence nearly zero decibel insertion loss is expected with modulation depth (extinction ratio) exceeding 25 dB. Here, the modulation mechanism relies on switching this waveguide system from a critical coupling regime to AE condition via electrostatically tuning the free-carrier concentration and hence the optical index of a thin indium thin oxide (ITO) layer resides in the plasmonic center waveguide. This alters the effective coupling length and the phase mismatching condition thus modulating in each of its outer waveguides. Our results also promise a power consumption as low as 49.74aJ/bit. Besides, we expected a modulation speed of 160 GHz reaching to millimeter wave range applications. Such anticipated performance is a direct result of both the unity-strong tunability of the plasmonic optical mode in conjunction with utilizing ultra-sensitive modal coupling between the critically coupled and the AE regimes. When taken together, this new class of modulators paves the way for next generation both for energy and speed conscience optical short-reach communication such as those found in interconnects.

scholarly journals An Ultra-CompactOptical Modulator using Indium Tin Oxide Materialand Metal-Dielectric-Metal Waveguide Structure

2019 ◽  
Vol 8 (6) ◽  
pp. 463-466 ◽  
Keyword(s):  
Integrated Circuits ◽  
Tin Oxide ◽  
Integrated Circuit ◽  
Indium Tin Oxide ◽  
High Speed ◽  
Modulation Depth ◽  
Research Area ◽  
Tunable Filter ◽  
Waveguide Structure ◽  
Telecommunication Wavelength

These days Ultra-compact modulators are seeking so much interest in their research area, because these are the main components of optical transmission systems and also Ultracompact and ultra- high speed semiconductor electronic modulators are very significant for optoelectronic integrated circuits. The resonant modulators can be of very small size therefor we have proposed a compactIndium Tin Oxide (ITO) based Opto- Electronic Modulator in a Metal-Dielectric-Metal Plasmonic Waveguide Structure and utilizing resonance property in the device. The device has dimension of 0.01 μm3 and shows modulation depth approximately 9 dB near telecommunication wavelength of 1.5 μm. All the calculations had been done using Finite Element Method (FEM). We have also studied the applications of the device as a tunable filter near the telecommunication wavelength. Performance of the suggested device is quite acceptable with comparison to device size and considered valuable for photonic integrated circuit.

scholarly journals Coupling-enhanced dual ITO layer electro-absorption modulator in silicon photonics

Nanophotonics ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 1559-1566 ◽  
Author(s):  
Mohammad H. Tahersima ◽  
Zhizhen Ma ◽  
Yaliang Gui ◽  
Shuai Sun ◽  
Hao Wang ◽  
...  
Keyword(s):  
Indium Tin Oxide ◽  
Modulation Depth ◽  
Extinction Ratio ◽  
Active Material ◽  
Oxide Phase ◽  
Modern Technology ◽  
High Performing ◽  
Performance Improvements ◽  
Electro Optic ◽  
On Chip

AbstractElectro-optic signal modulation provides a key functionality in modern technology and information networks. Photonic integration has not only enabled miniaturizing photonic components, but also provided performance improvements due to co-design addressing both electrical and optical device rules. The millimeter to centimeter footprint of many foundry-ready electro-optic modulators, however, limits density scaling of on-chip photonic systems. To address these limitations, here we experimentally demonstrate a coupling-enhanced electro-absorption modulator by heterogeneously integrating a novel dual-gated indium-tin-oxide phase-shifting tunable absorber placed at a silicon directional coupler region. This concept allows utilizing the normally parasitic Kramers-Kronig relations here in an synergistic way resulting in a strong modulation depth to insertion loss ratio of about 1. Our experimental modulator shows a 2 dB extinction ratio for a just 4 μm short device at 4 V bias. Since no optical resonances are deployed, this device shows spectrally broadband operation as demonstrated here across the entire C-band. In conclusion, we demonstrate a modulator utilizing strong index change from both real and imaginary parts of active material enabling compact and high-performing modulators using semiconductor near-foundry materials.

scholarly journals Manipulation of epsilon-near-zero wavelength for the optimization of linear and nonlinear absorption by supercritical fluid

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jiaye Wu ◽  
Xuanyi Liu ◽  
Haishi Fu ◽  
Kuan-Chang Chang ◽  
Shengdong Zhang ◽  
...  
Keyword(s):  
Supercritical Fluid ◽  
Indium Tin Oxide ◽  
Nonlinear Absorption ◽  
Modulation Depth ◽  
Saturable Absorption ◽  
Time Saving ◽  
Nanophotonic Devices ◽  
Absorption Performance ◽  
Linear And Nonlinear ◽  
Epsilon Near Zero

AbstractWe introduce supercritical fluid (SCF) technology to epsilon-near-zero (ENZ) photonics for the first time and experimentally demonstrate the manipulation of the ENZ wavelength for the enhancement of linear and nonlinear optical absorption in ENZ indium tin oxide (ITO) nanolayer. Inspired by the SCF’s applications in repairing defects, reconnecting bonds, introducing dopants, and boosting the performance of microelectronic devices, here, this technique is used to exploit the influence of the electronic properties on optical characteristics. By reducing oxygen vacancies and electron scattering in the SCF oxidation process, the ENZ wavelength is shifted by 23.25 nm, the intrinsic loss is reduced by 20%, and the saturable absorption modulation depth is enhanced by > 30%. The proposed technique offers a time-saving low-temperature technique to optimize the linear and nonlinear absorption performance of plasmonics-based ENZ nanophotonic devices.

scholarly journals Asymmetric Ge/SiGe coupled quantum well modulators

Nanophotonics ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1765-1773
Author(s):  
Yi Zhang ◽  
Jianfeng Gao ◽  
Senbiao Qin ◽  
Ming Cheng ◽  
Kang Wang ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Quantum Well ◽  
Quantum Wells ◽  
High Speed ◽  
Low Voltage ◽  
Extinction Ratio ◽  
High Frequency Response ◽  
Modulation Format ◽  
Silicon Photonic ◽  
Coupled Quantum Well

Abstract We design and demonstrate an asymmetric Ge/SiGe coupled quantum well (CQW) waveguide modulator for both intensity and phase modulation with a low bias voltage in silicon photonic integration. The asymmetric CQWs consisting of two quantum wells with different widths are employed as the active region to enhance the electro-optical characteristics of the device by controlling the coupling of the wave functions. The fabricated device can realize 5 dB extinction ratio at 1446 nm and 1.4 × 10−3 electrorefractive index variation at 1530 nm with the associated modulation efficiency V π L π of 0.055 V cm under 1 V reverse bias. The 3 dB bandwidth for high frequency response is 27 GHz under 1 V bias and the energy consumption per bit is less than 100 fJ/bit. The proposed device offers a pathway towards a low voltage, low energy consumption, high speed and compact modulator for silicon photonic integrated devices, as well as opens possibilities for achieving advanced modulation format in a more compact and simple frame.

Study of Flow Boiling Characteristics of a Microchannel Using High Speed Visualization

2013 ◽  
Vol 135 (8) ◽  
Author(s):  
Rashid Ali ◽  
Björn Palm ◽  
Claudi Martin-Callizo ◽  
Mohammad H. Maqbool
Keyword(s):  
Heat Flux ◽  
Flow Pattern ◽  
Indium Tin Oxide ◽  
High Speed ◽  
Liquid Velocity ◽  
Flow Boiling ◽  
Fused Silica ◽  
Internal Diameter ◽  
Electrically Conductive ◽  
Heated Length

This paper presents the visualization results obtained for an experimental study of R134a during flow boiling in a horizontal microchannel. The microchannel used was a fused silica tube having an internal diameter of 781 μm, a heated length of 191 mm, and was coated with a thin, transparent, and electrically conductive layer of indium-tin-oxide (ITO) on the outer surface. The operating parameters during the experiments were: mass flux 100–400 kg/m2 s, heat flux 5–45 kW/m2, saturation temperatures 25 and 30 °C, corresponding to saturation pressures of 6.65 bar and 7.70 bar and reduced pressures of 0.163 and 0.189, respectively. A high speed camera with a close up lens was used to capture the flow patterns that evolved along the channel. Flow pattern maps are presented in terms of the superficial gas and liquid velocity and in terms of the Reynolds number and vapor quality plots. The results are compared with some flow pattern maps for conventional and micro scale channels available in the literature. Rigorous boiling and increased coalescence rates were observed with an increase in the heat flux.

High-Speed Δβ-Reversal Directional Coupler Modulator with Low Insertion Loss for 1.3 μm in LiNbO3

1984 ◽  
Vol 5 (1) ◽  
Author(s):  
F. Auracher ◽  
D. Schicketanz ◽  
K.-H. Zeitler
Keyword(s):  
Insertion Loss ◽  
High Speed ◽  
Directional Coupler ◽  
Low Insertion Loss ◽  
Directional Coupler Modulator

SummaryWe report on a very fast (≥ 6 Gbit/s) Δβ-reversal directional-coupler modulator with low insertion loss (2 dB) for 1.3 μm wavelength operation. The design of the modulator permits easy and reproducible fabrication.

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