Effect Of Shot Noise Research Articles

Photon flux requirements for extreme ultraviolet reticle imaging in the 22- and 16-nm nodes

Extreme UV (EUV)-wavelength actinic microscopy yields detailed information about EUV mask patterns, architectures, defects, and the performance of defect repair strategies without the complications of photoresist imaging.To understand the pattern measurement limits of EUV mask microscopy, we investigate the effects of shot noise on aerial image linewidth measurements in the 22- and 16-nm lithography generations. Using a simple model we probe the influence of photon shot noise on measured, apparent line roughness, and find general flux density requirements independent of the specific EUV microscope configurations. Analysis reveals the trade-offs between photon energy density, effective pixel dimension on the CCD, and image log slope (ILS). We find that shot-noise-induced linewidth roughness (LWR) varies inversely with the square root of the photon energy density and is proportional to the magnification ratio. While high magnification is necessary for adequate spatial resolution, for a given flux density, higher magnification ratios have diminishing benefits. We find that to achieve an LWR (3) value of 5% of linewidth for dense, 88-nm mask features with a 2.52 normalized ILS value (image log-slope, ILS, equal to 28.6/µm) and 13.5-nm effective pixel width (1000 × magnification ratio), a peak photon flux of approximately 1400 photons/pixel per exposure is required.

TIRF-Based FRET with One Base-Pair Resolution

Single-molecule FRET (smFRET) is commonly used as a “nanoscale ruler” for the measurement of biomolecular distances and distance changes. However, the limits of FRET resolution for measurements on surface-immobilized molecules have not been rigorously explored. Using total-internal reflection fluorescence (TIRF) microscopy on a set of DNA standards and advanced image analysis software, we have quantified and extended the limits of FRET resolution associated with the use of electron-multiplying CCD (EMCCD) cameras. For such measurements, we derived a novel theoretical description of the major sources of noise ( photon shot noise, background, CCD noise and pixelation effects); we find excellent agreement between our experimental results and predictions from theory and Monte Carlo simulations. For FRET measurements on a truly single-molecule basis (as opposed to measurements on an ensemble of single molecules), analysis of the experimental noise allows us to predict a resolution of 4% FRET within the linear FRET range (20-80%), sufficient to directly observe a distance difference equivalent to one DNA base-pair separation (3.4 A). For FRET distributions obtained from an ensemble of single molecules (which exhibits broadening due to presence of static heterogeneity), we demonstrate the ability to distinguish between distances differing by as little as 2 base pairs (∼7A). Current work focuses on real-time observation of single-base-pair translocation steps of Escherichia coli RNA polymerase within single early transcription-elongation complexes; such observations are crucial for understanding the mechanisms of DNA and RNA polymerases.Our work paves the way for ultra-high resolution studies of processes involving conformational changes and protein translocation on nucleic acids.

Effect of the Coulomb interaction for shot noise in a quantum dot

The correlation effect of shot noise through a quantum dot is investigated for the symmetric case at zero temperature. Employing the renormalized perturbation theory, we calculate the shot noise S h and the Fano factor F b = S h / 2 eI b for a backscattering current I b . The Fano factor is shown to have the universal form of F b = 1 + 4 ( R − 1 ) 2 / ( 1 + 5 ( R − 1 ) 2 ) with the Wilson ratio R in any strength of the Coulomb interaction.

Simulation of shot noise effect on CD and LER of electron-beam lithography in 32 nm designs

Mask fabrication or even maskless lithography operations are performed with electron-beam lithography (EBL). The detailed understanding of the electron scattering mechanisms in resist films and multilayer substrates, as well as on substrates with topography is mandatory. Along the same track the problem of line edge roughness (LER) of created structures is emerging, because it strongly affects the device electrical behavior. Process simulation could be used for the quantification of the effects of electron-beam exposure and resist material on the produced layout. In the current work coupling between a detailed Monte-Carlo e-beam–matter interaction simulator and a stochastic resist film modeling simulator for the materials, postexposure bake, and development allows for simulation of the shot noise, resist material, and process effects on the critical dimension (CD) and LER in the 32 technology patterned by direct EBL. An example of quantification of shot noise and resist contribution to LER is provided.

Single-Photon Resolution CMOS Integrating Image Sensors

A CMOS image sensor – realized in a commercially available 0.18μm CIS technology – for near “single-photon detection” applications is presented. The pixel array features 1.2e- readout noise and 2.5e- overall noise comprising dark current shot noise effects at 60 frames per second (16μs row-time). The 11μm x 11μm pixel (fill factor of 63%) provides a pixel conversion gain of 50μV/e-. High-dynamic range of over 150dB is achieved.Further research on noise in charge detector circuits has resulted in the invention of a novel ultra-low-noise pixel featuring in-pixel amplification enabling single-electron resolution imaging. A typical sense node referred readout noise of 0.9e- and an overall sense node referred noise floor of 1.5e- are measured at a pixel conversion gain of 300μV/e-.

Design and Demonstration of a Novel Spectral Amplitude Coding OCDMA Code for Suppression Phase Intensity Induced Noise

A new code for spectral-amplitude coding optical code-division multiple-access system is proposed called Random diagonal (RD) code. This code is constructed using code segment and data segment. One of the important properties of this code is that the cross correlation at data segment is always zero, which means that Phase Intensity Induced Noise (PIIN) is reduced. For the performance analysis, the effects of phase-induced intensity noise, shot noise, and thermal noise are considered simultaneously. Bit-error rate (BER) performance is compared with Hadamard and Modified Frequency Hopping (MFH) codes. It is shown that the system using this new code matrices not only suppress PIIN, but also allows larger number of active users compare with other codes. Simulation results shown that using point to point transmission with three encoded channels, RD code has better BER performance than other codes, also its found that at 0 dbm PIIN noise are 10 -10 and 10 -11 for RD and MFH codes respectively.

Statistical Analysis of Phase-Inversion Neutron Specular Reflectivity

The phase-inversion approach to neutron specular reflection is elucidated in a formal setting, in order to emphasize its conceptual coherence and to facilitate study of some of its statistical properties in the context of real data. An operational notion of data degradation is introduced and illustrated with the randomizing effects of shot noise ("counting" noise) and the systematic "bias" induced by data truncation. Some basic statistical effects of phase-inversion are worked out in the new formalism and illustrated by simulated examples. A principal is advanced that phase-inversion sets the limit of available information from specular reflection.

Improvement of Speech Quality in Distance-Based Howling Canceller

In this paper, we propose a distance-based howling canceller with high speech quality. We have developed a distance-based howling canceller that uses only distance information by noticing the property that howling occurs according to the distance between a loudspeaker and a microphone. This method estimates the distance by transmitting a pilot signal from the loudspeaker to the microphone. Multiple frequency candidates for each howling are computed from the estimated distance and eliminated by cascading notch filters that have nulls at them. However degradation of speech quality occurs at the howling canceller output. The first cause is a shot noise occurrence at the beginning and end of the pilot signal transmission due to the discontinuous change of the amplitude. We thus develop a new pilot signal that is robust against ambient noises. We can then reduce the shot noise effect by taking the amplitude small. The second one is a speech degradation caused from overlapped stopbands of the notch filters. We thus derive a condition on the bandwidths so that stopbands do not overlap, and propose an adaptive bandwidth scheme which changes the bandwidth according to the distance.

The effect of shot noise on the start up of the fundamental and harmonics in free-electron lasers

The problem of radiation start up in free-electron lasers (FELs) is important in the simulation of virtually all FEL configurations including oscillators and amplifiers in both seeded master oscillator power amplifier (MOPA) and self-amplified spontaneous emission (SASE) modes. Both oscillators and SASE FELs start up from spontaneous emission due to shot noise on the electron beam, which arises from the random fluctuations in the phase distribution of the electrons. The injected power in a MOPA is usually large enough to overwhelm the shot noise. However, this noise must be treated correctly in order to model the initial start up of the harmonics. In this paper, we discuss and compare two different shot noise models that are implemented in both one-dimensional wiggler-averaged (PERSEO) and non-wiggler-averaged (MEDUSA1D) simulation codes, and a three-dimensional non-wiggler-averaged (MEDUSA) formulation. These models are compared for examples describing both SASE and MOPA configurations in one dimension, in steady-state, and time-dependent simulations. Remarkable agreement is found between PERSEO and MEDUSA1D for the evolution of the fundamental and harmonics. In addition, three-dimensional correction factors have been included in the MEDUSA1D and PERSEO, which show reasonable agreement with MEDUSA for a sample MOPA in steady-state and time-dependent simulations.

Effect of signal quantum shot noise on the jitter of leading edge detected and high-pass discriminated laser pulse signals

Effects of signal quantum shot noise on the jitter properties of laser pulses detected by a typical time-of-flight laser radar receiver channel configuration have been studied. Simulation and measurement results show that the optimal leading edge detection level in a typical industrial measurement situation with a PIN-diode detector is at the maximum point of the timing pulse slew rate. For avalanche photodiodes (APD) at the same signal to noise ratio, defined at the input of the preamplifier, the optimum detection level is lower due to the effect of signal quantum shot noise. In high-pass discrimination the optimum timing discrimination time constant is higher with an APD receiver than with a PIN-diode receiver due to signal quantum shot noise. In addition, it was noted that the optimum APD gain from the jitter point of view is less than the maximum gain in certain measurement situations.

Term Structure Models with Shot-Noise Effects

This work proposes term structure models consisting of two parts: a part which can be represented in exponential quadratic form and a shot noise part. These term structure models allow for explicit expressions of various derivatives. In particular, they are very well suited for credit risk models. The goal of the paper is twofold. First, a number of key building blocks useful in term structure modelling are derived in closed-form. Second, these building blocks are applied to single and portfolio credit risk. This approach generalizes Duffie & Gýrleanu (2001) and is able to produce realistic default correlation and default clustering. We conclude with a specific model where all key building blocks are computed explicitly.

HGHG schemes for short wavelengths

In this paper, we discuss a method to design a single-stage high Gain Harmonic Generation (HGHG) scheme with the aid of GENESIS 1.3 numerical code. To properly design an HGHG scheme, shot-noise effects in both undulators as well as the effect of the energy spread induced by the FEL process in the modulator have to be taken into account. We design the device evaluating these undesired effects separately in each stage and simulating the joint effects on the final configuration. The method will be illustrated following the example of an HGHG scheme for the SPARX project.

Models of longitudinal space-charge impedance for microbunching instability

A 1D model of space-charge impedance, assuming a transversely uniform beam with circular cross section, has been proposed and is being extensively used in the modeling of the microbunching instability of relevance for the beam delivery systems of x-ray free-electron lasers. In this paper we investigate the limitation of the model when applied to studying the effect of shot noise---one of the sources of the microbunching instability. We make comparison with a fully 3D calculation and identify the upper end of the frequency spectrum for applicability of the 1D model. Relaxation of the assumptions regarding axis symmetry and uniformity of the transverse density is also reviewed.

Visual Reliability and Information Rate in the Retina of a Nocturnal Bee

Nocturnal animals relying on vision typically have eyes that are optically and morphologically adapted for both increased sensitivity and greater information capacity in dim light. Here, we investigate whether adaptations for increased sensitivity also are found in their photoreceptors by using closely related and fast-flying nocturnal and diurnal bees as model animals. The nocturnal bee Megalopta genalis is capable of foraging and homing by using visually discriminated landmarks at starlight intensities. Megalopta's near relative, Lasioglossum leucozonium, performs these tasks only in bright sunshine. By recording intracellular responses to Gaussian white-noise stimuli, we show that photoreceptors in Megalopta actually code less information at most light levels than those in Lasioglossum. However, as in several other nocturnal arthropods, Megalopta's photoreceptors possess a much greater gain of transduction, indicating that nocturnal photoreceptors trade information capacity for sensitivity. By sacrificing photoreceptor signal-to-noise ratio and information capacity in dim light for an increased gain and, thus, an increased sensitivity, this strategy can benefit nocturnal insects that use neural summation to improve visual reliability at night.

A SHOT NOISE MODEL FOR FINANCIAL ASSETS

In this article we propose and study a model for stock prices which allows for shot-noise effects. This means that abrupt changes caused by jumps may fade away as time goes by. This model is incomplete. We derive the minimal martingale measure in discrete and continuous time and discuss the associated hedging strategy. Finally, a simulation study is included to show that our model is able to produce smile effects.

Effects of Electron Shot Noise and Quantum Field Fluctuations on the Photon Statistics of the Coherent Spontaneous Harmonic Radiation

We present a theoretical analysis of the statistical fluctuations in the coherent spontaneous harmonic radiation (CSHR) generated by a free electron laser (FEL) under the conditions applicable in a previously published experiment [1] where sub-Poisson optical fluctuations were observed. The numerical analyses presented here document the conclusion that the emission of CSHR can serve as a useful test bed for analyses of the nonclassical aspects of electron beam formation and radiation. Two possible explanations for the observed fluctuations in the CSHR are investigated as limiting physical mechanisms: the fluctuations in the number density of the radiating electrons, the so-called and the quantum fluctuations in the radiation field. When the uncertainties in the radiation field are considered as the only noise source as in the analysis, the statistical fluctuations in the CSHR would result in Poisson statistics. On the other hand, when the electron shot noise is regarded as the only noise contribution as assumed by the shot-noise model, we find numerically and analytically that the fluctuations, as characterized by the Fano factor, would be much smaller than those due to the quantum uncertainties in the radiation field in the analysis. The experimentally observed fluctuations are larger than those due to shot noise, but smaller than those due to quantum fluctuations in the field. Hence, neither the classical shot-noise model nor the quasi-classical analysis can explain the experimental results. Given the results presented in this report, it is clear that attention must be given to the other phenomena-including the quantum fluctuations in the electromagnetic field and the nonclassical electron correlation, which contributed to the observed laser fluctuations.

Multiple access interference cancellation in Manchester-coded synchronous optical PPM-CDMA network

A new interference cancellation technique for direct-detection optical code- division multiple-access (OCDMA) network employing pulse-position modulation (PPM) is proposed in this paper. The multiple access interference (MAI) estimation is achieved by pre-reserving one of optical spreading code sequences at the receiver based on the correlation property of padded modified prime codes (PMPC). The estimated interference is then cancelled out after photo-detection process. Additionally, the transmitted signal is Manchester-coded to further improve the system performance. Based on this proposed interference canceller in a shot-noise limited regime, we have obtained an expression for the upper bound of the bit-error probability (BEP) taking into account effects of both MAI and shot-noise. This BEP is compared with that of a PPM-OCDMA without cancellation. Finally, the receiver structure of the proposed optical network unit (ONU) is fairly simple to compare with the conventional cancellation schemes.

Performance analysis of coherence multiplexed turbo-coded optical pulse position modulated code division multiple access systems

The significant features of coherence multiplexing technique are applied to a turbo-coded optical pulse position modulated (PPM) code division multiple access (CDMA) system with differential detection, and its performance is evaluated in terms of bit-error rate (BER) by including the effects of thermal noise, beat noise, and shot noise. It is shown that around 98 users can be accommodated at a signal-to-noise ratio (SNR) of 2.0 dB for a fixed BER of 9.6688×10−6. A significant reduction in BER of around 3.2355×10−16 is achieved for an increased SNR of 7.2916 dB supporting 53 users for a source linewidth of 20 nm. On increasing the linewidth to 40 nm, the number of users is found to increase from 53 to 75 for the same BER and SNR. The reduction of BER of 3.2355×10−16, 6.6473×10−18, and 2.1089×10−19 is obtained at an SNR of 7.29 dB for increasing interleaver lengths of 10, 32, and 100, respectively. The BER reduction by decreasing the user data rates is also presented. On comparison with the direct detection, the number of simultaneous users that can be accommodated at a BER of 10−16 is found to increase from 31 to 54 users.

Turbo-coding of Coherence Multiplexed Optical PPM CDMA System With Balanced Detection

The effects of turbo-coding on the coherence multiplexed optical PPM CDMA systems are shown by evaluating bit error rate (BER) with respect to system parameters such as interleaver length (K), number of simultaneous users (N), code length (f), initial pulsewidth (t0) and normalized threshold (I¸) by including the effects of thermal noise and shot noise. Turbo-codes increase the number of simultaneous users besides reducing the BER for a decreasing normalized threshold. As the initial pulsewidth reduces from 7ps to 5ps the BER reduces from 1.6392x10-17 to 7.0167x10-18. For a fixed number of simultaneous users (N=20), an initial pulsewidth, (t0 = 5ps) and a normalized threshold (I¸ = 0.84), it is seen that the turbo-codes of interleaver length 10 reduces BER in the order 10-10, 10-18 and 10-32 for the code length varying as 63, 127 and 255 respectively. On comparison with the direct detection it is found that the balanced detection could accommodate an additional number of 8 users at a reduced BER of 10-16.

Shot-noise processes and the minimal martingale measure

This article proposes a model for stock prices which incorporates shot-noise effects. This means, that sudden jumps in the stock price are allowed, but their effect may decline as time passes by. Our model is general enough to capture arbitrary effects of this type. Generalizing previous approaches to shot noise we in particular allow the decay to be stochastic. This model describes an incomplete market, so that the martingale measure is not unique. We derive the minimal martingale measure via continuous time methods.