Quantum filtering theory and the reduction of dark count, dark current and optical crosstalk in optical detectors

AbstractApplication specific Lab-on-Microchips (ALMs) making use of the combination of complex microfluidic networks with microelectronic circuits and micro optical components allow the realization of miniaturized application specific biological and chemical processing and analysis devices. Fluorescence sensing is one of the most widely used detection technologies, e.g. for DNA fluorescence labelling in Micro Capillary Electrophoresis (µCE) due to its superior sensitivity and specificity. Unfortunately, commercially available fluorescence sensing systems are physically very large, non portable, expensive and constrain the analysis in portable diagnostic and medical care. Integrated semiconductor optoelectronic devices can provide a portable, parallel and inexpensive solution for on chip fluorescence sensing.Most µCE applications working in the spectral range of visible light. For the integration of optical detection components a photon energy range of 1.6 eV - 3.1 eV is of interest. The a-Si:H technology accomplished due to the low dark current and high absorption coefficient against to crystalline silicon the requirements in that spectral range. In this paper we combine a:Si-H photo sensors with a fluidic micro system to detect the fluorescence of a rhodamine analyte mixture. The analyte mixture was excited by light with a wavelength in the range of λEx = 450 - 490 nm. The a-Si:H detector reveals a low dark current density on the order of 10-10 A/cm2 and a sufficient dynamic range of ∼100 dB under illumination of ∼1000 lx as a function of bias voltage. The measurement shows that the movement of the rhodamine plug in the microchannel causes a significant rise in the pin-diode photo current, which correlates to the evaluated signal of a microscope image detector. The photo current difference for excitation and additional fluorescence amounts to 2.4 µA.

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PMT background

10.1093/oso/9780199565092.003.0006 ◽

2017 ◽

Author(s):

A. G. Wright

Keyword(s):

Gamma Rays ◽

Dark Current ◽

Pulse Height ◽

Thermionic Emission ◽

Dark Count ◽

Leakage Currents ◽

Dark Counts ◽

Residual Gas ◽

Radioactive Background ◽

Emission Light

Photomultiplier (PMT) background derives from sources of photons, and from photoelectrons generation within a PMT. These may also act as a source of optical and radioactive background for neighbouring detectors. Dark count and dark current are reconciled by allowing for leakage currents flowing into the anode. The optimal gain setting follows from these considerations. Sources of background generated by the photocathode include thermionic emission; light generated within the PMT; gamma rays; muons and minimum ionizing particles (MIPs); insulator glow in the region of the anode; and residual gas. Pulse height distributions for dark counts, in terms of photoelectrons equivalent, reveal the size and magnitude distributions of the various contributions. Temperature and gain dependence are also covered. PMTs constructed from low radioactive glass provide ultra-low background.

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High performance InGaAs/InP avalanche photodiode integrated with metal-insulator-metal microcavity

10.21203/rs.3.rs-298600/v1 ◽

2021 ◽

Author(s):

Hao Han ◽

Yicheng Zhu ◽

Zilu Guo ◽

Zhifeng Li ◽

Huidan Qu ◽

...

Keyword(s):

Dark Current ◽

High Performance ◽

Detection Efficiency ◽

Coupling Effect ◽

Signal To Noise Ratio ◽

Avalanche Photodiode ◽

Metal Insulator ◽

Joint Simulation ◽

Optical Crosstalk ◽

Metal Insulator Metal

Abstract Reducing the dark current of InGaAs/InP avalanche photodiodes (APDs) is an important way to improve its performance. Decreasing the active size can reduce the dark current but sacrifice the quantum efficiency. In this paper, the Metal-Insulator-Metal (MIM) microcavity is integrated with an APD, which can converge light from tens of microns to several microns, to compensate for the loss of detection efficiency caused by the reduction of the size of the APD. Through photoelectric joint simulation, the optical response of the device can be obtained, and the coupling effect between the MIM structure and the APD can be analyzed directly. The simulation results show that the signal to noise ratio of the APD integrated with the MIM microcavity is twice of the MIM free traditional APD, and the 3dB bandwidth reaches 5.8 GHz. When the MIM microcavity is applied to an APD array, the optical crosstalk between pixels is found to be negligible.

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