It is, by now, well known that McIntyre's localized carrier-multiplication theory cannot explain the suppression of excess noise factor observed in avalanche photodiodes (APDs) make use thin multiplication regions. We demonstrate a carrier model incorporates effects dead space, as developed earlier Hayat et al. provides excellent agreement with impact-ionization and characteristics InP, In/sub 0.52/Al/sub 0.48/As, GaAs, Al/sub 0.2/Ga/sub 0.8/As APDs, regions different widths. outline general...

The effect of dead space on the mean gain, excess noise factor, and avalanche breakdown voltage for Si GaAs photodiodes (APDs) with nonuniform carrier ionization coefficients are examined. space, which is a function electric field position within multiplication region APD, minimum distance that newly generated must travel in order to acquire sufficient energy become capable causing impact ionization. Recurrence relations form coupled linear integral equations derived characterize underlying...

Abstract Sublominal and superluminal propagation of light normal anomalous rotary photon drag are investigated in this manuscript using control fields milnor polynomial. Crater type absorption spectrum is having a central peak at origin with variation positions. The normal
and dispersion arc associated low high region. group index varying the range -1 x 107 ≤ ng 1 107. This correspond to velocity vg = c/ng varies -30m/s 30m/s. maximum positive negative delay time measured ±0.002s. It...

The conventional McIntyre carrier multiplication theory for avalanche photodiodes (APDs) does not adequately describe the experimental results obtained from APDs with thin multiplication-regions. Using published data GaAs and Al/sub 0.2/Ga/sub 0.8/As APDs, collected multiplication-regions of different widths, we show that incorporating dead-space in model resolves discrepancy. ionization coefficients enabled carriers have traveled dead space are determined as functions electric field, within...

The history-dependent recurrence theory for multiplication noise in avalanche photodiodes (APDs), developed by Hayat et al., is generalized to include inter-layer boundary effects heterostructure APDs with multilayer regions. These the initial energy of injected carriers as well bandgap-transition within a region. It shown that excess factor can be significantly reduced if process initiated an energetic carrier, which case serves reduce dead space associated carrier. An reduction up 40%...

Quantum-dot infrared photodetectors (QDIPs) exhibit a bias-dependent shift in their spectral response. In this paper, novel signal-processing technique is developed that exploits diversity to synthesize measurements are tuned wide range of user-specified spectra. The based on two steps: desired response first optimally approximated by weighted superposition family bias-controlled spectra the QDIP, corresponding preselected set biases. Second, multiple taken object be probed, one for each...

It has been recently found that the initial-energy effect, which is associated with finite initial energy of carriers entering multiplication region an avalanche photodiode (APD), can be tailored to reduce excess noise well beyond previously known limits for thin APDs. However, control injected difficult in practice APD a single layer. In this paper, dead-space recurrence theory used show low characteristics effect achieved by utilizing two-layer region. As example, high bandgap Al <sub...

The recurrence theory for the breakdown probability in avalanche photodiodes (APDs) is generalized to heterostructure APDs that may have multiple multiplication layers. generalization addresses layer-boundary effects such as initial energy of injected carriers well layer-dependent profile dead space region. Reducing width layer serves both downshift and sharpen curve a function applied reverse-bias voltage. In structures where an comparable ionization threshold energy, transition from linear...

The dead-space multiplication theory of Hayat and Saleh [J. Lightwave Technol. 10, 1415 (1992)], in conjunction with the multiplication-width-independent ionization-coefficient model developed by et al. [IEEE Trans. Electron Devices 47, 625 (2000)], are shown to accurately predict breakdown voltages for thin avalanche photodiodes GaAs, InP, In0.52Al0.48As, Al0.2Ga0.8As, over a broad range device widths. voltage is determined from analytical expression impulse-response-function decay rate.

Mean-gain and excess-noise measurements are presented for a 350 × μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> P+/N-well/P-sub 270 N-well/P-sub avalanche photodetectors fabricated using 0.13-μm CMOS technology. The active area of the device was divided into multiple subsections to decrease transit time increase speed. For P+/N-well structure, remarkably low factors 4.1 4 were measured at mean gain 16 corresponding k value...

It has recently been reported that by using a spectral-tuning algorithm, the photocurrents of multiple detectors with spectrally overlapping responsivities can be optimally combined to synthesize, within certain limits, response detector an arbitrary responsivity. However, it is known presence noise in photocurrent degrade performance this algorithm significantly, depending on choice responsivity spectrum synthesized. We generalize accommodate noise. The results are applied quantum-dot...

While quantum dots-in-a-well (DWELL) infrared photodetectors have the feature that their spectral responses can be shifted continuously by varying applied bias, width of response at any bias is not sufficiently narrow for use in multispectral sensing without aid filters. To achieve higher resolutions using physical filters, algorithms been developed post-processing DWELL's bias-dependent photocurrents resulting from probing an object interest repeatedly over a wide range biases. At heart...

Mid-wave and long-wave infrared (IR) quantum-dots-in-a-well (DWELL) focal plane arrays (FPAs) are promising technology for multispectral (MS) imaging sensing. The DWELL structure design provides the detector with a unique property that allows spectral response of to be continuously, albeit coarsely, tuned applied bias. In this paper, MS classification capability FPA is demonstrated. approach based upon: 1) an object repeatedly using sequence bias voltages in tuning range then 2) applying...

Recent reports on the effects of vibrating targets synthetic-aperture radar (SAR) imagery and potential SAR to extract non-stationary signatures have drawn significant interest from remote-sensing community. returned signals are superposition transmitted pulses modulated by both static non-static in amplitude phase. More precisely, vibration a target causes small sinusoid-like frequency modulation along synthetic aperture (slow time), whereby phase deviation is proportional displacement...

The well-known analytical formula for the excess noise factor associated with avalanche photodiodes (APDs), developed by R. J. McIntyre in 1966, assumes injection of either an electron or a hole at edge APD's region. This is based on statistics probabilities carriers gaining and losing energy subject to high electric fields. However, this formula, not applicable cases when photons are absorbed inside region (even though physics field transport remains same), its use may severely...

We report development of array compatible individual high-performance quantum dot pixel structures that allow for spectral tuning by the application an external bias. Custom-made post-processing algorithms have been used to further enhance and optimize their spectral-separation capability far beyond device limit. The dots-in-a-well (DWELL) detector consists 10 layers InAs dots placed in a thin InGaAs well, which turn is GaAs matrix. DWELL structure provides good confinement carriers trapped dots.

Quantum-dot infrared photodetectors (QDIPs), based on intersubband transitions in nanoscale self-assembled dots, are perceived as a promising technology for mid-infrared-regime sensing since they mature GaAs technology, sensitive to normal incidence radiation, exhibit large quantum confined stark effect that can be exploited hyperspectral imaging, and have lower dark currents than their well counterparts. High detectivity (D* = 1.0E11 cmHz^1/2/W at 9 microns) QDIPs been recently...

A method that does not use numerical integration is presented for approximating the cumulative distribution of integer-valued random variables from their characteristic functions. Bounds on approximation error are also given. The then used to compute photomultiplier counting distributions.

A theory is presented addressing the fundamental limits of image estimation in a setup that uses two photon-correlated beams. These beams have property their photon arrivals, as point process, are ideally synchronized time and space. The true represents spatial distribution optical transmittance (or reflectance) an object. In this setup, one beam used to probe while other reference providing additional information on actual number photons impinging This exploited reduce effect quantum noise...

This study is motivated by the emergence of a new class tunable infrared spectral-imaging sensors that offer ability to dynamically vary sensor's intrinsic spectral response from frame in an electronically controlled fashion. A manifestation this when sequence dissimilar responses periodically realized, whereby every period acquired imagery, each associated with distinct band. Traditional scene-based global shift estimation algorithms are not applicable such spectrally heterogeneous video...

In this paper, recent developments in post-processing techniques for quantum-dot infrared detectors (QDIPs) and provide spectral tuning classification examples that show potential capability of QDIPs as hyperspectral multispectral sensors

The dead-space carrier multiplication theory properly predicts the reduction in excess noise factor a number of APDs. is applied to measurements, obtained from J. C. Campbell and collaborators at University Texas, for InP, InAlAs, GaAs, AlGaAs APDs with multiplication-region widths ranging 80 nm 1600 nm. A refined model ionization coefficients reported that independent width device region each device. In addition, comparison predictions conventional theory, mean bandwidth as well power...

In recent years, our group has developed and reported two multispectral sensing algorithms that aim to exploit the continuous bias-dependent spectral tunability of quantum dots-in-a-well (DWELL) infrared photodetector enable higher resolutions without using filters. The key idea is probe an unknown target interest sequentially with DWELL detector at multiple biases, producing a set photocurrents. Then, post-processing algorithm performs linear superposition these photocurrents pre-determined...