Design of an On-Chip Plasmonic Modulator Based on Hybrid Orthogonal Junctions Using Vanadium Dioxide

We present the design of a plasmonic modulator based on hybrid orthogonal silver junctions using vanadium dioxide as the modulating material on a silicon-on-insulator. The modulator has an ultra-compact footprint of 1.8 μm × 1 μm with a 100 nm × 100 nm modulating section based on the hybrid orthogonal geometry. The modulator takes advantage of the large change in the refractive index of vanadium dioxide during its phase transition to achieve a high modulation depth of 46.89 dB/μm. The simulated device has potential applications in the development of next generation high frequency photonic modulators for optical communications which require nanometer scale footprints, large modulation depth and small insertion losses.

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Hybrid Graphene-Silicon Based Polarization-Insensitive Electro-Absorption Modulator with High-Modulation Efficiency and Ultra-Broad Bandwidth

Nanomaterials ◽

10.3390/nano9020157 ◽

2019 ◽

Vol 9 (2) ◽

pp. 157 ◽

Cited By ~ 4

Author(s):

Yin Xu ◽

Feng Li ◽

Zhe Kang ◽

Dongmei Huang ◽

Xianting Zhang ◽

...

Keyword(s):

Optical Interconnects ◽

Modulation Depth ◽

Polarization State ◽

Broad Bandwidth ◽

Graphene Layers ◽

Silicon Waveguide ◽

High Modulation ◽

Polarization Insensitive ◽

On Chip ◽

Silicon Based

Polarization-insensitive modulation, i.e., overcoming the limit of conventional modulators operating under only a single-polarization state, is desirable for high-capacity on-chip optical interconnects. Here, we propose a hybrid graphene-silicon-based polarization-insensitive electro-absorption modulator (EAM) with high-modulation efficiency and ultra-broad bandwidth. The hybrid graphene-silicon waveguide is formed by leveraging multi-deposited and multi-transferred methods to enable light interaction with graphene layers in its intense field distribution region instead of the commonly used weak cladding region, thus resulting in enhanced light–graphene interaction. By optimizing the dimensions of all hybrid graphene-silicon waveguide layers, polarization-insensitive modulation is achieved with a modulation efficiency (ME) of ~1.11 dB/µm for both polarizations (ME discrepancy < 0.006 dB/µm), which outperforms that of previous reports. Based on this excellent modulation performance, we designed a hybrid graphene-silicon-based EAM with a length of only 20 µm. The modulation depth (MD) and insertion loss obtained were higher than 22 dB and lower than 0.23 dB at 1.55 µm, respectively, for both polarizations. Meanwhile, its allowable bandwidth can exceed 300 nm by keeping MD more than 20 dB and MD discrepancy less than 2 dB, simultaneously, and its electrical properties were also analyzed. Therefore, the proposed device can be applied in on-chip optical interconnects.

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On-chip scalable mode-selective converter based on asymmetrical micro-racetrack resonators

Nanophotonics ◽

10.1515/nanoph-2020-0040 ◽

2020 ◽

Vol 9 (6) ◽

pp. 1447-1455

Author(s):

Huifu Xiao ◽

Zhenfu Zhang ◽

Junbo Yang ◽

Xu Han ◽

Wenping Chen ◽

...

Keyword(s):

Large Scale ◽

Optical Network ◽

Monochromatic Light ◽

Network On Chip ◽

Silicon On Insulator ◽

Intelligent Network ◽

Silicon Waveguides ◽

Mode Division Multiplexing ◽

Potential Applications ◽

On Chip

AbstractMode division multiplexing (MDM) technology has been well known to researchers for its ability to increase the link capacity of photonic network. While various mode processing devices were demonstrated in recent years, the reconfigurability of multi-mode processing devices, which is vital for large-scale multi-functional networks, is rarely developed. In this paper, we first propose and experimentally demonstrate a scalable mode-selective converter using asymmetrical micro-racetrack resonators (MRRs) for optical network-on-chip. The proposed device, composed of cascaded MRRs, is able to convert the input monochromatic light to an arbitrary supported mode in the output waveguide as required. Thermo-optical effect of silicon waveguides is adopted to tune the working states of the device. To test the utility, a device for proof-of-concept is fabricated and experimentally demonstrated based on silicon-on-insulator substrate. The measured spectra of the device show that the extinction ratios of MRRs are larger than 18 dB, and modal crosstalk for selected modes are all less than −16.5 dB. The switching time of the fabricated device is in the level of about 40 μs. The proposed device is believed to have potential applications in multi-functional and intelligent network-on-chip, especially in reconfigurable MDM networks.

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Double-layer graphene on photonic crystal waveguide electro-absorption modulator with 12 GHz bandwidth

Nanophotonics ◽

10.1515/nanoph-2019-0381 ◽

2019 ◽

Vol 9 (8) ◽

pp. 2377-2385 ◽

Cited By ~ 4

Author(s):

Zhao Cheng ◽

Xiaolong Zhu ◽

Michael Galili ◽

Lars Hagedorn Frandsen ◽

Hao Hu ◽

...

Keyword(s):

Photonic Crystal ◽

Double Layer ◽

Slow Light ◽

Modulation Depth ◽

Photonic Crystal Waveguide ◽

Optical Modulators ◽

Layer Graphene ◽

Silicon Photonic ◽

On Chip ◽

Silicon Based

AbstractGraphene has been widely used in silicon-based optical modulators for its ultra-broadband light absorption and ultrafast optoelectronic response. By incorporating graphene and slow-light silicon photonic crystal waveguide (PhCW), here we propose and experimentally demonstrate a unique double-layer graphene electro-absorption modulator in telecommunication applications. The modulator exhibits a modulation depth of 0.5 dB/μm with a bandwidth of 13.6 GHz, while graphene coverage length is only 1.2 μm in simulations. We also fabricated the graphene modulator on silicon platform, and the device achieved a modulation bandwidth at 12 GHz. The proposed graphene-PhCW modulator may have potentials in the applications of on-chip interconnections.

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Electromechanically reconfigurable optical nano-kirigami

Nature Communications ◽

10.1038/s41467-021-21565-x ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Shanshan Chen ◽

Zhiguang Liu ◽

Huifeng Du ◽

Chengchun Tang ◽

Chang-Yin Ji ◽

...

Keyword(s):

Near Infrared ◽

Large Range ◽

Three Dimensional ◽

High Contrast ◽

Si Substrate ◽

High Modulation ◽

Gold Nanostructure ◽

Infrared Wavelengths ◽

On Chip ◽

Nano Electromechanical System

AbstractKirigami, with facile and automated fashion of three-dimensional (3D) transformations, offers an unconventional approach for realizing cutting-edge optical nano-electromechanical systems. Here, we demonstrate an on-chip and electromechanically reconfigurable nano-kirigami with optical functionalities. The nano-electromechanical system is built on an Au/SiO2/Si substrate and operated via attractive electrostatic forces between the top gold nanostructure and bottom silicon substrate. Large-range nano-kirigami like 3D deformations are clearly observed and reversibly engineered, with scalable pitch size down to 0.975 μm. Broadband nonresonant and narrowband resonant optical reconfigurations are achieved at visible and near-infrared wavelengths, respectively, with a high modulation contrast up to 494%. On-chip modulation of optical helicity is further demonstrated in submicron nano-kirigami at near-infrared wavelengths. Such small-size and high-contrast reconfigurable optical nano-kirigami provides advanced methodologies and platforms for versatile on-chip manipulation of light at nanoscale.

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Towards lab-on-chip ultrasensitive ethanol detection using photonic crystal waveguide operating in the mid infrared

Nanophotonics ◽

10.1515/nanoph-2020-0576 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Ali Rostamian ◽

Ehsan Madadi-Kandjani ◽

Hamed Dalir ◽

Volker J. Sorger ◽

Ray T. Chen

Keyword(s):

Photonic Crystal ◽

Slow Light ◽

High Sensitivity ◽

Guided Wave ◽

Silicon On Insulator ◽

Group Index ◽

Photonic Crystal Waveguide ◽

Mid Infrared ◽

Lab On Chip ◽

On Chip

Abstract Thanks to the unique molecular fingerprints in the mid-infrared spectral region, absorption spectroscopy in this regime has attracted widespread attention in recent years. Contrary to commercially available infrared spectrometers, which are limited by being bulky and cost-intensive, laboratory-on-chip infrared spectrometers can offer sensor advancements including raw sensing performance in addition to use such as enhanced portability. Several platforms have been proposed in the past for on-chip ethanol detection. However, selective sensing with high sensitivity at room temperature has remained a challenge. Here, we experimentally demonstrate an on-chip ethyl alcohol sensor based on a holey photonic crystal waveguide on silicon on insulator-based photonics sensing platform offering an enhanced photoabsorption thus improving sensitivity. This is achieved by designing and engineering an optical slow-light mode with a high group-index of n g = 73 and a strong localization of modal power in analyte, enabled by the photonic crystal waveguide structure. This approach includes a codesign paradigm that uniquely features an increased effective path length traversed by the guided wave through the to-be-sensed gas analyte. This PIC-based lab-on-chip sensor is exemplary, spectrally designed to operate at the center wavelength of 3.4 μm to match the peak absorbance for ethanol. However, the slow-light enhancement concept is universal offering to cover a wide design-window and spectral ranges towards sensing a plurality of gas species. Using the holey photonic crystal waveguide, we demonstrate the capability of achieving parts per billion levels of gas detection precision. High sensitivity combined with tailorable spectral range along with a compact form-factor enables a new class of portable photonic sensor platforms when combined with integrated with quantum cascade laser and detectors.

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Germanium Photodiode Arrays on Silicon-On-Insulator with On-Chip Bias Circuit

IEEE Photonics Technology Letters ◽

10.1109/lpt.2021.3064505 ◽

2021 ◽

pp. 1-1

Author(s):

Keye Sun ◽

Junyi Gao ◽

Robert Costanzo ◽

Ta-Ching Tzu ◽

Steven M. Bowers ◽

...

Keyword(s):

Silicon On Insulator ◽

Photodiode Arrays ◽

On Chip

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Dual-Tunable Polarization Insensitive Electromagnetically Induced Transparency in Metamaterials

Journal of Electronic Materials ◽

10.1007/s11664-020-08692-9 ◽

2021 ◽

Author(s):

Renxia Ning ◽

Zhiqiang Xiao ◽

Zhenhai Chen ◽

Wei Huang

Keyword(s):

Vanadium Dioxide ◽

Mode Coupling ◽

Slow Light ◽

Chemical Potential ◽

Electromagnetically Induced Transparency ◽

Dark Mode ◽

Potential Applications ◽

Polarization Insensitive ◽

Terahertz Devices ◽

Induced Transparency

AbstractA multilayer structure of a square ring of graphene with nesting vanadium dioxide (VO2) was investigated in this study. This structure exhibits electromagnetically induced transparency (EIT), which stems from a bright mode coupling with a dark mode. The permittivity values of graphene and VO2 can be modulated via chemical potential and temperature, respectively. The EIT effect can be tuned based on the chemical potential of graphene and temperature of VO2, resulting in a dual-tunable EIT effect. Simulation results confirmed that this dual-tunable EIT phenomenon is insensitive to polarization. These results may have potential applications in terahertz devices, such as slow light devices, switching devices, and sensors.

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Neural Rate and Timing Cues for Detection and Discrimination of Amplitude-Modulated Tones in the Awake Rabbit Inferior Colliculus

Journal of Neurophysiology ◽

10.1152/jn.00776.2006 ◽

2007 ◽

Vol 97 (1) ◽

pp. 522-539 ◽

Cited By ~ 51

Author(s):

Paul C. Nelson ◽

Laurel H. Carney

Keyword(s):

Inferior Colliculus ◽

Dynamic Range ◽

Modulation Depth ◽

Average Rate ◽

Modulation Frequency ◽

Detection Threshold ◽

Depth Functions ◽

Depth Discrimination ◽

High Modulation ◽

Envelope Processing

Neural responses to amplitude-modulated (AM) tones in the unanesthetized rabbit inferior colliculus (IC) were studied in an effort to establish explicit relationships between physiological and psychophysical measures of temporal envelope processing. Specifically, responses to variations in modulation depth ( m) at the cell’s best modulation frequency, with and without modulation maskers, were quantified in terms of average rate and synchronization to the envelope over the entire perceptual dynamic range of depths. Statistically significant variations in the metrics were used to define neural AM detection and discrimination thresholds. Synchrony emerged at modulation depths comparable with psychophysical AM detection sensitivities in some neurons, whereas the lowest rate-based neural thresholds could not account for psychoacoustical thresholds. The majority of rate thresholds (85%) were −10 dB or higher (in 20 log m), and 16% of the population exhibited no systematic dependence of average rate on m. Neural thresholds for AM detection did not decrease systematically at higher SPLs (as observed psychophysically): thresholds remained constant or increased with level for most cells tested at multiple sound-pressure levels (SPLs). At depths higher than the rate-based detection threshold, some rate modulation-depth functions were sufficiently steep with respect to the across-trial variability of the rate to predict depth discrimination thresholds as low as 1 dB (comparable with the psychophysics). Synchrony, on the other hand, did not vary systematically with m in many cells at high modulation depths. A simple computational model was extended to reproduce several features of the modulation frequency and depth dependence of both transient and sustained pure-tone responders.

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