Quantum detectors

IR detectors convert (thermal) radiation energy into electrical signals. Two classes of such detectors exist thermal detectors and quantum detectors. 

Quantum detectors are based on semiconductors. The absorption of a photon excites an electron from the valence band into the conduction band. This can be measured either through a change in resistance (photoconductive... 

G. R. Fleming With regard to the question of Prof. Quack, let me add that Jeff Cina has incorporated a quantum detector into his model of fluorescence up-conversion experiments [1],... 

The name quantum detector is given to a radiometric detector having equal or near equal response over the entire range to be measured, UV or VIS and calibrated in quantum units. As is the case for all meters, they may be calibrated for any... 

The ideal quantum detector response curve is a square wave, i.e., equally sensitive over the entire wavelength range of measurement. These types of detectors should be used for all measurements of incident intensity, UV and VIS, if a spec-troradiometer is not available. While spectrally blind they will at least give a truer reading of the total amount of radiation actually being received by the samples. Figure 7 shows the response curves of two of these detectors. 

These units when coupled with near linear (quantum) detector sensors are useful for monitoring processes for total incident intensity on a sample. One should remember, however, that because they are spectrally blind, if change is noted it will be difficult to know just where in the spectrum band this is being measured, if it occurred. 

Currently there are two main methods of mapping in use in the industry, the use of Quinine Actinometry and the use of radiometer/photometer combinations as presented by the ICH (1). Neither of these methods covers the entire range of wavelengths of interest and if modified to do so by employing "quantum detectors" would still not give any wavelength information. 

The detector converts infrared radiation into an electrical signal. The two main classes of detectors are thermal and quantum detectors. The heating caused by impinging infrared radiation changes some physical properties of the thermal detector itself. In quantum detectors, the quantum nature of infrared radiation changes the detector s electrical properties. 

Quantum detectors are usually made of semiconductor materials or mixtures. Some commonly used quantum detectors are made of lead sulfide (PbS), lead selenide (PbSe), indium antimony (InSb), or mercury cadmium telluride (MCT, HgTe-CdTe). The absorption of infrared radiation in quantum detectors excites electrons... 

QUANTUM DETECTOR OF NOISE BASED ON SUPERCONDUCTOR NANOSTRUCTURES... 

According to theoretical and experimental results obtained recently a dc voltage can be induced by a switching of superconductor ring between states with different connectivity of wave function. This effect can be used for development of a quantum detector of noise with the ultimate sensitivity. Our experimental investigations confirm such possiUlity. 

Fig. 10. The proposed structure of the SET-hased readout circuit for THz detector. The quantum detector cell (QDC), which is the triple Q-dot system, is capacitively coupled through the sense electrode to a carbon based nanotubes RF-SET. A bias-electrode is used to control the bias potential on the sense electrode.

A particular kind of quantum detector (or photodetector) used in laboratories and industry is known as the thermopile detector. In an experiment, it is desired to measure the radiation from a black flat plate extending to infinity, A detector has been placed parallel to the plate. The catalog of the detector indicates that the maximum allowable incident radiation is 200 mW/oii5. Determine the highest tolerable plate temperature which will not damage the thermopile detector. Neglect the radiation emitted by the detector itself. 

As indicated in Figure 7-, b, there arc two general types of radiation transducers. One type responds to photons, the other to heat. All photon transducers (also called phoforli ciric or quantum detectors) have an active surface (hat absorbs radiation. In some types. 

The results presented above can be expanded to modulated, noncoherent, and nonparallel beam mixing. As an example, we consider two ideal amplitude-stabilized nonparallel [9>X/d) plane traveling waves impinging on a two-quantum detector, so that washboarding can occur. In contrast to the one-quantum case, the detector responds to the square of this spatiotemporal... 

As a final example, we consider mixing due to radiation which is non-sinusoidal (i.e., not coherent to all orders). We consider two parallel, plane-polarized normally incident superimposed beams of radiation from the same chaotic source, one of which is a time-delayed version of the other (delay tg) entering one double-quantum detector. This was previously shown to be equivalent to a self-integrating Hanbury-Brown-Twiss device [7.34]. For a thermal source in the absence of a beat signal, we find... 

Although the emphasis in this section has been on linearly polarized incident radiation, considerable enhancement of the k-quantum photocurrent may occur for circularly (or elliptically) polarized radiation, as recently discussed by a number of authors [7.46]. We note that information relating to the intermediate-state lifetime of the detector (t,) can be obtained by measuring the two-quantum detector output for various values of t. ... 

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