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High-energy dissipative soliton resonance and rectangular noise-like pulse in a figure-9 Tm fiber laser
摘要： We experimentally demonstrate a direct generation of high-energy dissipative soliton resonance (DSR) and rectangular noise-like pulse (NLP) in a figure-9 thulium-holmium-doped mode-locked fiber laser. The pulse duration and average output power of the DSR can be tuned from 33.5 ns to 144.6 ns, and from 100.25 mW to 677.5 mW, respectively. The maximum of pulse energy is 713.2 nJ without wave breaking at pump power of 6.7 W, which is the highest energy of DSR in the region of 2 μm, to the best of our knowledge. In addition, the rectangular NLP with 452 nJ pulse bunch energy is also obtained.
关键词： dissipative soliton resonance,noise-like pulse,high-energy pulses,thulium-holmium-doped fiber laser
更新于2025-11-28 14:24:03
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Demonstration of linewidth measurement based on phase noise analysis for a single frequency fiber laser in the 2 <i>μ</i> m band
摘要： Linewidth measurement based on phase noise analysis using a 3 × 3 coupler has been applied in the 1550 nm band. One of the obvious advantages of this method compared with the common delayed self-heterodyne method is the low loss caused by the short delay line used. Taking full advantage of this particular characteristic, the linewidth of the single frequency (SF) fiber laser in the 2 μm band can also be measured. However, a specifically experimental demonstration of this method in the 2 μm band is absent to date. In this paper, a high-performance SF thulium-doped fiber laser (TDFL) was proposed and employed for the demonstration. The TDFL operates at the center wavelength of 1942.03 nm with high stability. By means of the phase noise analysis-based linewidth measurement system with a fiber delay line of only 50 m, the linewidth of the proposed TDFL is successfully measured. When the measuring time is 0.001 s, the linewidth is ~47 kHz. Furthermore, the noise characteristics of the SF laser were simultaneously studied by this method.
关键词： 2 μm band,phase noise,single frequency fiber laser,linewidth measurement
更新于2025-11-28 14:23:57
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Optimized signal-to-noise ratio with shot noise limited detection in Stimulated Raman Scattering microscopy
摘要： We describe our set-up for Stimulated Raman Scattering (SRS) microscopy with shot noise limited detection for a broad window of biologically relevant laser powers. This set-up is used to demonstrate that the highest signal-to-noise ratio (SNR) in SRS with shot noise limited detection is achieved with a time-averaged laser power ratio of 1:2 of the unmodulated and modulated beam. In SRS, two different coloured laser beams are incident on a sample. If the energy difference between them matches a molecular vibration of a molecule, energy can be transferred from one beam to the other. By applying amplitude modulation to one of the beams, the modulation transfer to the other beam can be measured. The efficiency of this process is a direct measure for the number of molecules of interest in the focal volume. Combined with laser scanning microscopy, this technique allows for fast and sensitive imaging with sub-micrometre resolution. Recent technological advances have resulted in an improvement of the sensitivity of SRS applications, but few show shot noise limited detection. The dominant noise source in this SRS microscope is the shot noise of the unmodulated, detected beam. Under the assumption that photodamage is linear with the total laser power, the optimal SNR shifts away from equal beam powers, where the most signal is generated, to a 1:2 power ratio. Under these conditions the SNR is maximized and the total laser power that could induce photodamage is minimized. Compared to using a 1:1 laser power ratio, we show improved image quality and a signal-to-noise ratio improvement of 8 % in polystyrene beads and C. Elegans worms. Including a non-linear damage mechanism in the analysis, we find that the optimal power ratio converges to a 1:1 ratio with increasing order of the non-linear damage mechanism.
关键词： shot noise limited detection,signal-to-noise ratio,Nonlinear Raman microscopy
更新于2025-11-21 11:08:12
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Low-Voltage, Full-Swing InGaZnO-Based Inverters Enabled by Solution-Processed, Ultra-Thin AlxOy
摘要： High-performance, full-swing inverters implemented with InGaZnO thin-film transistors (TFTs) have been demonstrated capable of operating at a very low voltage. The threshold voltage of the load and drive TFTs were modified through careful change of the gate dielectric anodization voltage. Both the load and drive TFTs show excellent electrical properties including a current on/off ratio > 106 and a subthreshold swing close to the theoretical limit. As a result, the inverters show high voltage gains up to 34 at a supply voltage of only 1 V as well as high noise margins > 92% of the theoretical maximum. The devices and the fabrication process might have potential applications in future wearable and disposable electronics where low cost and low power are vital.
关键词： InGaZnO,one-volt operation,high voltage gain and noise margins,full-swing inverters
更新于2025-11-14 17:28:48
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A novel natural image noise level estimation based on flat patches and local statistics
摘要： This paper proposes a high-precision algorithm for noise level estimation. Different from existing algorithms, we present a new noise level estimation algorithm by linearly combining the overestimated and underestimated results using combinatorial coefficients that can be tailored to the problem at hand. The algorithm has two distinct features: it avoids the underestimation of noise level estimation algorithms that employ the minimum eigenvalue and demonstrates higher accuracy and robustness for a large range of visual content and noise conditions. The experimental results that are obtained in this study demonstrate that the proposed algorithm is effective for various scenes with various noise levels. The software release of the proposed algorithm is available online at https://ww2.mathworks.cn/matlabcentral/fileexchange/64519-natural-image-noise-level-estimation-based-on-flat-patches-and-local-statistics.
关键词： Covariance matrix,Eigenvalue,Flat patches,Gaussian noise,Noise level estimation
更新于2025-09-23 15:23:52
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Pre-treatment for preventing degradation of measurement accuracy from speckle noise in speckle interferometry
摘要： Speckle interferometers, which can measure three-dimensional deformations with the same sensitivity in each direction of a three-dimensional axis, have been employed in the industry. However, the measurement results of a complex shape deformation using this method do not always produce a smooth phase map due to the influence of speckle noise. In this paper, this problem that occurs with speckle noise, which is included in the speckle pattern, is discussed. In addition, the solution to the problem concerning speckle noise is discussed. An idea for noise reduction is proposed by using a simple speckle pattern intensity distribution model based on the interferometry. It is confirmed that the proposed method can reduce the influence of speckle noise to 1/1000 of the light source wavelength.
关键词： Noise reduction,Influence of speckle noise,High resolution deformation measurement,ESPI (electronic speckle pattern interferometry)
更新于2025-09-23 15:23:52
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Oil Slick Detection in the Offshore Domain: Evaluation of Polarization-Dependent Sar Parameters
摘要： Remote sensing technology is an essential link in the global monitoring of the ocean surface and radars are efficient sensors for detecting marine pollution. When used operationally, a tradeoff must usually be made between the covered area and the quantity of information collected by the radar. To identify the most appropriate imaging mode, a methodology based on Receiver Operating Characteristic (ROC) curve analysis has been applied to an original dataset collected by an airborne system, SETHI, characterized by a very low instrument noise floor. The dataset was acquired during an oil spill clean-up exercise carried out in 2015 in the North Sea. Various polarization-dependent quantities are investigated and a relative ordering of the main polarimetric parameters is reported. VV offers the best tradeoff between the benefit of detection performance and the instrument and data requirements. When the sensor has a sufficiently low noise floor, HV is also recommended because it provides strong slick-sea contrast. Among all the investigated quad-polarimetric settings, no significant added value compared to single-polarized data was found.
关键词： NESZ,noise floor,sea,spill,detection,SAR,noise,slick,radar,marine pollution,probability of detection,oil,ROC curves,probability of false alarm,ocean,polarization
更新于2025-09-23 15:23:52
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[ACM Press the 2018 International Conference - Tianjin, China (2018.09.19-2018.09.21)] Proceedings of the 2018 International Conference on Electronics and Electrical Engineering Technology - EEET '18 - An Exploratory Analysis of Speckle Noise Removal Methods for Satellite Images
摘要： image processing procedure, Satellite images captured in a variety of modalities serve as the primary source for many applications. Satellite image processing extracts the image /spectral information represented in the form of pixels, classifies those pixels based on the similarity measures and further analyzes the inherent data, as per the requirements. The foremost objective of satellite processing is to automatically categorize the pixels in an image into the respective land cover class labels or themes. These pixels are classified by its spectral information and it is determined by the relative reflectance in various bands of wavelength. The accuracy and outcomes of any satellite the application domain, directly depends on its quality. Satellite images are invariably degraded by speckle noise. Hence, preprocessing the images for speckle noise suppression and/or cloud removal is deemed an inevitable component in satellite image processing. Researchers have proposed a spectrum of methods for speckle noise/cloud removal. A detailed review on the significant research publications on speckle noise removal are summarized in this article. The consolidation of methodology merits and demerits of the select research articles are presented in this paper. This review article on speckle noise removal is designed as a ready-reference for those researchers working in satellite image processing. irrespective of
关键词： RADAR,SAR,Review,Speckle Noise,Satellite images,Noise filters,Literature Survey
更新于2025-09-23 15:23:52
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Device noise reduction for silicon nanowire field-effect-transistor based sensors by using a Schottky junction gate
摘要： The sensitivity of metal-oxide-semiconductor field-effect transistor (MOSFET) based nanoscale sensors is ultimately limited by noise induced by carrier trapping/detrapping processes at the gate oxide/semiconductor interfaces. We have designed a Schottky junction gated silicon nanowire field-effect transistor (SiNW-SJGFET) sensor, where the Schottky junction replaces the noisy oxide/semiconductor interface. Our sensor exhibits significantly reduced device noise, 2.1×10-9 V2μm2/Hz at 1 Hz, compared to reference devices with the oxide/semiconductor interface operated at both inversion and depletion modes. Further improvement can be anticipated by wrapping the nanowire by such a Schottky junction thereby eliminating all oxide/semiconductor interfaces. Hence, a combination of the low-noise SiNW-SJGFET device with a sensing surface of the Nernstian response limit holds promises for future high signal-to-noise ratio sensor applications.
关键词： Noise reduction,field-effect transistor,ion sensor,low frequency noise,schottky junction gate,silicon nanowire
更新于2025-09-23 15:23:52
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Low-phase noise 8.22 GHz GaN HEMT oscillator using a feedback multi-path transformer
摘要： This article designs a low-phase noise 8.22 GHz GaN high electron-mobility transistor (HEMT) oscillator in the WIN 0.25 μm GaN HEMT process. The oscillator uses a HEMT amplifier with a transformer as the feedback network. The transformer uses a 3-path secondary inductor and a single-path primary inductor. The GaN oscillator consumes the power 4.328 mW and generates a signal at 8.22 GHz with an output power ?11.35 dBm. At 1 MHz frequency offset from the carrier at 8.22 GHz the phase noise is ?120.82 dBc/Hz, the figure of merit of the proposed oscillator is ?192.76 dBc/Hz. The oscillator chip occupies an area of 2 × 1 mm2.
关键词： phase noise,3-path transformer,figure of merit,Q-factor,8.22 GHz GaN HEMT oscillator
更新于2025-09-23 15:23:52