User:Marshallsumter/Radiation astronomy2/Transductions

"Transduction refers to the process of converting one form of energy to another."

Theoretical transduction
Def. the "conversion of energy (especially light energy) into another form" is called transduction.

Def. the process of achieving transduction using individual quantum excitations" is called quantum transduction.

Motion transduction
"There is a recent surge of interest in amplification and detection of tiny motion in the growing field of opto and electro mechanics. [Widely] tunable, broad bandwidth and high gain all-mechanical motion amplifiers based on graphene/Silicon Nitride (SiNx) hybrids [have been demonstrated]. In these devices, a tiny motion of a large-area SiNx membrane is transduced to a much larger motion in a graphene drum resonator coupled to SiNx. Furthermore, the thermal noise of graphene is reduced (squeezed) through parametric tension modulation. The parameters of the amplifier are measured by photothermally actuating SiNx and interferometrically detecting graphene displacement. [Displacement] power gain of 38 dB and [...] 4.7 dB of squeezing resulting in a detection sensitivity of 3.8 fm/√Hz, close to the thermal noise limit of SiNx [have been demonstrated]."

Ultrasonic transduction
"Electrostatic and piezoelectric electromechanical coupling are employed in miniature devices to produce ultrasonic waves or generate power."

In "principle electrostatic devices can be designed to have an electromechanical coupling factor of nearly 100%".

A "model is general enough to allow a comparison of the two technologies, electrostatics and piezoelectrics, at a lower level of detail."

The "model is used to compare the components of the electromechanical coupling factor; capacitance, stiffness, and actuation force, for the two energy conversion technologies. The comparison shows that the capacitance and actuation force coefficient are drastically different for the two technologies, and are controlled by fundamental material properties and device geometries. Consequences of the differences for the design of ultrasonic transducers and power generation devices [exist]."

"The acoustical transduction in an array of ferroelectric domains with alternating piezoelectric coefficients is characterized by multi-frequency resonances, which occur at the boundary of the acoustic Brillouin zone (ABZ). The resonances correspond to two successive domain excitations in the first and second ABZ correspondingly, where the speed of ultrasound is somewhat different. An important parameter for acoustical transduction is the electric impedance Z. The results of the theoretical and experimental investigations of Z in a periodically poled LiNbO3 are presented. The magnitude and phase of Z depend on the array parameters including domain resonance frequency and domain number; Z of arrays consisting of up to 88 0.45-mm-long domains in the zx-cut crystal are investigated. The strong changes in Z-magnitude and phase are observed in the range of 3–4 MHz. The two resonance zones are within 3.33 ± 0.05 MHz and 3.67± 0.05 MHz. The change in domain number influences Z and its phase. By varying the number of inversely poled domains and resonance frequencies, one can significantly control/change the electrical impedance of the multidomain array."

Photonic transduction
"Modern Quantum Information Systems (QIS) employ optical photons for long distance communication, operating at ambient temperature, between microwave cavities, which house microwave photons used in quantum computing and microwave detection. These optical photons, carried by fiber-optic or free-space links, offer a low-cost, uncooled alternative to bulky, expensive microwave coaxial cables, which are lossy, susceptible to EMI, and a significant thermal conductor to the outside ambient environment. To convert between these two types of photons and implement these optical interconnects, it is necessary to develop a high-performance photodetector for optical to microwave transduction."

"In this Phase I effort, we collaborated in designing, fabricating, and testing an advanced, high-speed, high quantum efficiency prototype photodiode for transduction from optical to microwave frequencies."

"These devices have applications not only in quantum computing and axion detection, but also in other optical-cryogenic interconnect applications, in fields such as radio astronomy and quantum cryptography, as well as in quantum metrology and plasmonics."

"We designed an epitaxial stack, optimized in theory for ≥95% quantum efficiency at 795 nm, ≥5 GHz, per the target objectives of the program. Additionally, we designed a fabrication process and associated mask plates for top-illuminated, AR-coated devices with device diameters ranging from 50 µm to 800 µm. Using these, we fabricated two 3” wafer quarters of devices, and characterized the devices’ dark current, quantum efficiency, and bandwidth for various device diameters. The prototype devices achieved a quantum efficiency of 89% at the target 795 nm detection wavelength. The bandwidth of the devices proved tricky to characterize, but a 50 µm diameter device shows a 3-dB bandwidth of at least 1.6 GHz, possibly a full 5 GHz, depending on the measurement setup."

Strain and pressure sensors
"Piezo- and ferroelectric nanofibers of the polymer poly(vinylidenefluoride) (PVDF) have been widely employed in strain and pressure sensors as well as nanogenerators for energy harvesting. Despite this interest, the mechanism of electromechanical transduction is under debate and a deeper knowledge about relevant piezoelectric or electrostatic properties of nanofibers is crucial to optimize transduction efficiency. Here poly(vinylidenefluoride-trifluoroethylene) nanofibers at different electrospinning conditions are prepared. Macroscopic electromechanical response of fiber mats with microscopic analysis of single nanofibers performed by piezoelectric and electrostatic force microscopy are compared. The results show that electrospinning favors the formation of the piezoelectric β-phase in the polymer and leads directly to piezoelectric properties that are comparable to annealed thin films. However, during electrospinning the electric field is not strong enough to induce direct ferroelectric domain polarization. Instead accumulation of triboelectric surface charges and trapped space charge is observed in the polymer that explain the electret like macroscopic electromechanical response."

Hypotheses

 * 1) High-altitude gliders or balloons can provide a stable platform for observations that is as good as any satellite at much lower cost.