Terahertz (THz) fundamental "building blocks" equivalent to those used in multi-functional electronic circuits are very helpful for actual applications in THz data-processing technology and communication. Here, we theoretically and experimentally demonstrate a THz temporal differentiator based on an on-chip high-quality (Q) factor resonator. The resonator is made of low-loss high-resistivity silicon material in a monolithic, integrated platform, which is carefully designed to operate near the critical coupling region. The experiment demonstrates that the device can perform the first-order time derivative of the input signal electric field complex envelope at 214.72 GHz. Our investigation provides an effective approach for terahertz pulse re-shaping and real-time differential computing units.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1364/OE.387775 | DOI Listing |
We propose and demonstrate a tunable fractional-order photonic differentiator (DIFF) that can process input pulses with a sub-gigahertz bandwidth. Our scheme utilizes the self-induced optical modulation effect observed in a silicon-on-insulator micro-ring resonator. Gaussian-like pulses with varying pulse widths between 7.
View Article and Find Full Text PDFBiomedicines
January 2024
Brain Imaging and Analysis Center, Duke University Medical Center, Durham, NC 27710, USA.
Age-related macular degeneration (AMD) has recently been linked to cognitive impairment. We hypothesized that AMD modifies the brain aging trajectory, and we conducted a longitudinal diffusion MRI study on 40 participants (20 with AMD and 20 controls) to reveal the location, extent, and dynamics of AMD-related brain changes. Voxel-based analyses at the first visit identified reduced volume in AMD participants in the cuneate gyrus, associated with vision, and the temporal and bilateral cingulate gyrus, linked to higher cognition and memory.
View Article and Find Full Text PDFThis paper proposes a novel microring resonator (MRR)-based all-optical tuning temporal differentiator (DIFF). Specifically, the DIFF uses nonvolatile phase-change material GeSbTe (GST) to achieve low energy consumption and high-speed optical control of the state of the MRR, avoiding the traditional electro-optic (EO) and thermo-optic (TO) tuning designs. By changing the crystallinity of GST to changing the coupling regimes of the MRR, a broad range for the differentiation order α, i.
View Article and Find Full Text PDFUnder the trends of multifunctionality, tunability, and compactness in modern wave-based signal processors, in this paper, we propose a polarization-multiplexed graphene-based metasurface to realize distinct mathematical operators on the parallel time-domain channels enabled by vertical and horizontal polarizations. The designed metasurface is composed of two perpendicularly-oriented graphene strips for each of which the chemical potential can be dynamically tuned through a DC biasing circuit. The programmable metasurface exhibits two orthogonal channels through which the time-domain input signals are elaborately processed by separate mathematical functions.
View Article and Find Full Text PDFAn all-photonic approach of microwave waveforms generation and transformation is proposed and experimentally demonstrated. From the perspective of envelope function operation in time domain, an initial triangular waveform is transformed into square waveform and sawtooth (or reversed-sawtooth) waveform via two types of differentiators, respectively. In addition, by using a SOA as a multiplier, both bright and dark parabolic pulses are achieved, which are further transformed into sawtooth (or reversed-sawtooth) waveform by taking the first derivative operation.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!