Generating ultrafast pulses with better spectrotemporal control is crucial for optimizing and characterizing nonlinear light–matter responses, yet it is limited by the gain bandwidth of laser media ...or the phase‐matching geometry of nonlinear processes. This work proposes a simple approach to independently manage a femtosecond source's spectral location and bandwidth. Self‐phase‐modulation‐enabled spectral broadening is first analyzed, which is potentially energy‐scalable using hollow‐core capillaries or multipass cells. It is demonstrated that the outmost lobes in the broadened spectrum show different dependencies on the initial pulse energy and duration. A simple yet effective toy model is introduced that successfully predicts broadband spectral tuning, and the impact of other nonlinear effects, dispersion, and input pulse asymmetry on the experimental scenario is also discussed. Thus a fiber‐based versatile source is demonstrated, which is compressible down to its transform‐limit duration, as short as 12.2 fs centered at 920 nm. In addition, bandwidth‐dependent third‐harmonic generation spectroscopy is performed from a dielectric metasurface with an optimized nonlinear response, and the dependency of laser bandwidth and pulse duration is investigated on the signal‐to‐background ratio of two‐photon images. It is believed that this demonstration will advance the investigation of bandwidth‐dependent nonlinear spectroscopy and microscopy.
Independent control of femtosecond sources’ spectral location and bandwidth is realized with a simple approach enabled by self‐phase modulation. This work thus demonstrates a fiber‐based versatile source, delivering pulses compressible down to few‐optical‐cycle regimes. These demonstrations pave the way for deeper insights into the spectral response of nonlinear resonances, further advancing the field of bandwidth‐dependent nonlinear spectroscopy and microscopy.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The temperature coefficient (TC) of n-type polycrystalline silicon thin-film transistors (poly-Si TFTs) is investigated in this paper. The relationship between the TC and the activation energy is ...observed and explained. From the experimental results, it is also found that TC is not sensitive to the deviation of the laser crystallization energy. On the contrary, channel width can effectively modulate the TC of TFTs. By using the diode-connected poly-Si TFTs with different channel widths, the first voltage reference circuit with temperature compensation for precise analog circuit design on glass substrate is proposed and realized. From the experimental results in a low-temperature poly-Si process, the output voltage of voltage reference circuit with temperature compensation exhibits a very low TC of 195 ppm/degC , between 25degC and 125degC. The proposed voltage reference circuit with temperature compensation can be applied to design precise analog circuits for system-on-panel or system-on-glass applications, which enables the analog circuits to be integrated in the active-matrix liquid crystal display panels.
A 8 Phases 192MHz Crystal-Less Clock Generator with PVT Calibration LU, Ting-Chou; KER, Ming-Dou; ZAN, Hsiao-Wen ...
IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences,
2017/01/01, 2017-00-00, 20170101, Volume:
E100.A, Issue:
1
Journal Article
Peer reviewed
A multi-phase crystal-less clock generator (MPCLCG) with a process-voltage-temperature (PVT) calibration circuit is proposed. It operates at 192 MHz with 8 phases outputs, and is implemented as a ...0.18µm CMOS process for digital power management systems. A temperature calibrated circuit is proposed to align operational frequency under process and supply voltage variations. It occupies an area of 65µm × 75µm and consumes 1.1mW with the power supply of 1.8V. Temperature coefficient (TC) is 69.5ppm/°C from 0 to 100°C, and 2-point calibration is applied to calibrate PVT variation. The measured period jitter is a 4.58-ps RMS jitter and a 34.55-ps peak-to-peak jitter (P2P jitter) at 192MHz within 12.67k-hits. At 192MHz, it shows a 1-MHz-offset phase noise of -102dBc/Hz. Phase to phase errors and duty cycle errors are less than 5.5% and 4.3%, respectively.
By precisely managing fiber-optic nonlinearity with anomalous dispersion, we have demonstrated the control of generating plural few-optical-cycle pulses based on a 24-MHz Chromium:forsterite laser, ...allowing multicolor two-photon tissue imaging by wavelength mixing. The formation of high-order soliton and its efficient coupling to dispersive wave generation leads to phase-matched spectral broadening, and we have obtained a broadband continuum ranging from 830 nm to 1200 nm, delivering 5-nJ pulses with a pulse width of 10.5 fs using a piece of large-mode-area fiber. We locate the spectral enhancement at around 920 nm for the two-photon excitation of green fluorophores, and we can easily compress the resulting pulse close to its limited duration without the need for active pulse shaping. To optimize the wavelength mixing for sum-frequency excitation, we have realized the management of the power ratio and group delay between the soliton and dispersive wave by varying the initial pulse energy without additional delay control. We have thus demonstrated simultaneous three-color two-photon tissue imaging with contrast management between different signals. Our source optimization leads to efficient two-photon excitation reaching a 500-µm imaging depth under a low 14-mW illumination power. We believe our source development leads to an efficient and compact approach for driving multicolor two-photon fluorescence microscopy and other ultrafast investigations, such as strong-field-driven applications.
This paper presents a self-sustainable landslide surveillance system that detects hazardous water content level in soils and provides real-time landslide warnings to residents, without requiring ...wired electricity transmission. A self-powered soil water content sensor was applied as the trigger of alert event. It solves the energy supply problem by an environmental interrupt mechanism, which wakes up the sensor and communication circuits in a sensing node only when the water content in monitored soils exceeds a certain threshold, and thus completely eliminates the need for an ALS node to periodically wake up, sense and communicate. By tightly integrating energy harvesting, environment sensing and circuit wake-up, it may well be the most energy-efficient landslide surveillance system designed to monitor water content in soils in the world.
The electron distribution in an amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistor (TFT) with a floating metal-semiconductor (MS) back interface is analyzed using a technology ...computer-aided design (TCAD) model. The channel geometry (i.e., length and thickness) effect is carefully investigated. At a high work function (i.e., 5 eV) of the capping metal, electrons inside a-IGZO are mostly removed by the capping metal (electron depletion effect). The depletion of the IGZO film leads to an increase in threshold voltage in a-IGZO TFT. TCAD simulation reveals that increasing channel length and decreasing IGZO thickness significantly enhance such an electron depletion effect. Finally, the electron depletion effect is applied to a-IGZO TFT with a high-conductivity IGZO film to greatly suppress the leakage current by over 5 orders.
We have demonstrated widely tunable Yb:fiber-based laser sources, aiming to replace Ti:sapphire lasers for the nJ-level ultrafast applications, especially for the uses of nonlinear light microscopy. ...We investigated the influence of different input parameters to obtain an expansive spectral broadening, enabled by self-phase modulation and further reshaped by self-steepening, in the normal dispersion regime before the fiber damage. We also discussed the compressibility and intensity fluctuations of the demonstrated pulses, to reach the transform-limited duration with a very low intensity noise. Most importantly, we have demonstrated clear two-photon fluorescence images from UV-absorbing fluorophores to deep red dye stains.
A multi-phase crystal-less clock generator (MPCLCG) with a process-voltage-temperature (PVT) calibration circuit is proposed. It operates at 192 MHz with 8 phases outputs, and is implemented as a ...0.18 mu m CMOS process for digital power management systems. A temperature calibrated circuit is proposed to align operational frequency under process and supply voltage variations. It occupies an area of 65 mu m 75 mu m and consumes 1.1mW with the power supply of 1.8V. Temperature coefficient (TC) is 69.5ppm/ degree C from 0 to 100 degree C, and 2-point calibration is applied to calibrate PVT variation. The measured period jitter is a 4.58-ps RMS jitter and a 34.55-ps peak-to-peak jitter (P2P jitter) at 192MHz within 12.67k-hits. At 192MHz, it shows a 1-MHz-offset phase noise of -102dBc/Hz. Phase to phase errors and duty cycle errors are less than 5.5% and 4.3%, respectively.
Electronic frequency mixers are fundamental building blocks of electronic systems. Harmonic frequency mixing in particular enables broadband electromagnetic signal analysis across octaves of spectrum ...using a single local oscillator. However, conventional harmonic frequency mixers do not operate beyond hundreds of GHz to a few THz. If extended to the petahertz scale in a compact and scalable form, harmonic mixers would enable field-resolved optical signal analysis spanning octaves of spectra in a monolithic device without the need for frequency conversion using nonlinear crystals. Here we demonstrate lightwave-electronic harmonic frequency mixing beyond 0.350 PHz using plasmonic nanoantennas. We demonstrate that the mixing process enables complete, field-resolved detection of spectral content far outside that of the local oscillator, greatly extending the range of detectable frequencies compared to conventional heterodyning techniques. Our work has important implications for applications where optical signals of interest exhibit coherent femtosecond-scale dynamics spanning multiple harmonics.
Detection of tetracycline using isothermal amplification Chia-Cheng Wu; Li-An Wu; Yih-Fan Chen ...
2017 IEEE 12th International Conference on Nano/Micro Engineered and Molecular Systems (NEMS),
2017-April
Conference Proceeding
PCR is an important biosensing method since it can amplify DNA by many orders of magnitude. However, for food safety and environmental monitoring, the target molecule is usually not DNA. Here we ...demonstrate a detection method that integrates competitive assay format, magnetic bead separation, and isothermal DNA amplification for sensitive detection of tetracycline (TET) and other molecules. While TET is an antibiotic rather than oligonucleotide, our method allows the signal of TET detection to be amplified like conventional PCR. In addition, since we use isothermal amplification instead of conventional PCR, the temperature of the sample solution only needs to be maintained at a fixed temperature during the amplification process. We have successfully used the method to detect 10 pM TET. In addition, to improve the sensitivity of detection further, besides using EvaGreen dyes to quantify the amplified DNA, we have also tested another DNA quantification method that uses graphene oxide and a fluorescent DNA probe to increase the signal to background ratio of fluorescence detection.
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