A two-dimensional optical fibre microphone array with matrix-style data readout

Nakamura, Kentaro; Toda, Shuntaro; Yamanouchi, Makoto

doi:10.1088/0957-0233/12/7/319

Cited by 26 publications

(5 citation statements)

References 9 publications

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“…Group-III nitrides, which have tunable band gaps spanning the entire visible spectrum, are very interesting semiconductors for their numerous potential applications in electronics and optoelectronics, [1][2][3] and also for more fundamental applications such as polariton lasing. 4 More recently, Al x In 1−x N attracted some special attention due to the possibility of growing nearly lattice matched Al x In 1−x N/GaN heterostructures allowing the fabrication of crack-free and low threading dislocation (TD) density Bragg mirrors, 5,6 tunable interface strain high electron mobility transistors (HEMTs), 7 and infrared emitters based on intersubband transitions.…”

Section: Introductionmentioning

confidence: 99%

Stress-modulated composition in the vicinity of dislocations in nearly lattice matched AlxIn1−xN/GaN heterostructures: A po

et al. 2011

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Evidence of composition fluctuations around threading dislocations at scales ranging from atomic distances to tens of nanometers is provided by z-contrast imaging, strain measurement, and energy dispersive x-ray spectroscopy in Al x In 1−x N/GaN heterostructures. The atomic core rings of edge-type dislocations are shown to lie across highly antisymmetric elemental environments, and the indium-rich pit centers of mixed dislocation are found to lie on the tensile side of their atomic core ring. The observed composition fluctuations around pure-edge dislocations are compared with an elastostatic free energy model calculation and a good qualitative and quantitative agreement is obtained. Hydrostatic stress is shown to be their principal cause: Tensile stress regions are indium rich and compressive stress regions are aluminum rich. We show that the stress field of a mixed dislocation can impact the composition of the alloy more than a hundred nanometers away from its core. Indium core segregation on pure-screw threading dislocation is also evidenced and explained by the model, as shear stress is also expected to affect composition. Furthermore, threading dislocations are shown to bend less in the Al x In 1−x N alloy than in GaN, suggesting that they are "pinned" by stress-induced fluctuations. Such concentration modulations can have an important impact on optical and electrical properties of Group-III nitride devices that generally contain a high dislocation density (in the 10 8 to 10 10 cm −2 range). We propose that stress-induced composition modulation could be the origin of defect insensitivity in indium-containing nitride ternary alloys.

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Section: Introductionmentioning

confidence: 99%

Stress-modulated composition in the vicinity of dislocations in nearly lattice matched AlxIn1−xN/GaN heterostructures: A po

et al. 2011

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“…To characterize the electric properties of this photodetector for visible light, a white light emitting diode with adjustable illumination density is used to radiate gold electrode of the device. Due to the dark current denisity of photodetectors should be as low as possible in order to recognize weak signal current from noise (Nakamura et al, 2001 ; Li et al, 2020 ). The current density-voltage curves of our device under the sweep voltage from −100 V to 100 V at different illumination denisty are shown in Figure 3A .…”

Section: Resultsmentioning

confidence: 99%

Perovskite Photodetectors Based on p-i-n Junction With Epitaxial Electron-Blocking Layers

Wang

Pan

et al. 2020

Front. Chem.

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Organic-inorganic hybrid perovskite single crystals (PSCs) have been emerged as remarkable materials for some optoelectronic applications such as solid-state photodetectors, solar cells and light emitting diodes due to their excellent optoelectronic properties. To decrease the dark current, function layers based on spin-coating method are frequently requested for intrinsic PSCs to block the injected current by forming energy barrier. However, the amorphous function layers suffer from small carrier mobility and high traps density, which limit the speed of the photoelectric response of perovskite devices. This work supposes to grow thick MAPbBr 3 and MAPbI 3 mono-crystalline thin films on the surface of intrinsic MAPbBr 2.5 Cl 0.5 PSCs substrate by a heteroepitaxial growth technique to act as electron-blocking layers. Meanwhile, C60 and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) layers are deposited on the opposite surface of substrate PSCs by spin-coating method to block injected holes. This Au-MAPbI 3-MAPbBr 3-MAPbBr 2.5 Cl 0.5 PSCs-C60-PCBM-Ag heterostructure can be used as excellent X-ray photodetector (XPD) due to its low dark current density of 6.97 × 10 −11 A cm −2 at −0.5 V bias, high responsivity of 870 mA/W at −100 V bias and X-ray sensitivity as high as 59.7 µC mGy −1 cm −2 at −50 V bias.

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“…2,3) Over the past two decades, use of light to form a microphone has been reported in numerous works. [4][5][6][7][8][9][10][11] Most previous studies on optical microphones have focused on fiber optic-type measurement systems. [5][6][7][8] Among the various types of optical measurement technique that were proposed, light interference was useful for detection of aeroacoustic signals.…”

Section: Introductionmentioning

confidence: 99%

“…[4][5][6][7][8][9][10][11] Most previous studies on optical microphones have focused on fiber optic-type measurement systems. [5][6][7][8] Among the various types of optical measurement technique that were proposed, light interference was useful for detection of aeroacoustic signals. [9][10][11][12][13] One of the techniques developed in this period achieved detection of sounds propagating in the air, far away from the optical sensor, without use of optical fibers by applying Fraunhofer diffraction.…”

Section: Introductionmentioning

confidence: 99%

Modulation of optical speaker using biogenic guanine platelets floating in water

Iwasaka

2021

Preprint

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Microphones are miniature devices for sound detection. Various technologies have been developed to transfer sound properties onto other physical quantities, e.g., electricity. Over the past three decades, many studies have reported on optical sensing of sound. Most of these studies were performed via application of light interference at the edges of optical fibers. Several studies have reported on detection of sounds in the air or objects causing mechanical vibrations based on light interference. This work proposes an optical speaker which is a method to reconstruct and modulate sound from the power spectrum of light that has been reflected by guanine platelets floating in water droplet. The water droplet containing fish guanine platelets was placed on a piezoelectric membrane and acoustic vibration from the membrane propagated inside the droplet. A photomultiplier tube (PMT) then collected the light reflected from the water droplet. Without post-analysis of the measured light intensity, the analog output voltage from the PMT clearly sounded an audio speaker. In addition, it was found that the guanine platelets reflecting light operated as an audio equalizer.

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A two-dimensional optical fibre microphone array with matrix-style data readout

Cited by 26 publications

References 9 publications

Stress-modulated composition in the vicinity of dislocations in nearly lattice matched AlxIn1−xN/GaN heterostructures: A po

Stress-modulated composition in the vicinity of dislocations in nearly lattice matched AlxIn1−xN/GaN heterostructures: A po

Perovskite Photodetectors Based on p-i-n Junction With Epitaxial Electron-Blocking Layers

Modulation of optical speaker using biogenic guanine platelets floating in water

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