Photodiode Detector Research Articles

Resonant Tunneling Diodes: Mid-Infrared Sensing at Room Temperature.

Resonant tunneling diode photodetectors appear to be promising architectures with a simple design for mid-infrared sensing operations at room temperature. We fabricated resonant tunneling devices with GaInAsSb absorbers that allow operation in the μm range with significant electrical responsivity of 0.97 A/W at 2004 nm to optical readout. This paper characterizes the photosensor response contrasting different operational regimes and offering a comprehensive theoretical analysis of the main physical ingredients that rule the sensor functionalities and affect its performance. We demonstrate how the drift, accumulation, and escape efficiencies of photogenerated carriers influence the electrostatic modulation of the sensor’s electrical response and how they allow controlling the device’s sensing abilities.

Direct detection transmission of a PAM signal with power fading mitigation based on Alamouti coding and dual-drive MZM.

Power-fading impairment induced by fiber dispersion and photodiode detection imposes a fundamental limitation on the intensity-modulation direct-detection (IM-DD) transmission systems. In this work, we propose a cost-effective pulse-amplitude modulation (PAM) signal transmission scheme with power-fading mitigation enabled by Alamouti coding and dual-drive Mach-Zehnder modulator (DDMZM). By interleaving the symbol blocks in the time domain for upper- and lower-arm of the DDMZM, flat end-to-end frequency response can be obtained without spectral nulls after combining the photocurrents at odd and even time slots. For single channel demonstration, we experimentally transmit up to 160Gb/s PAM-4, 140Gb/s PAM-6, and 108Gb/s PAM-8 signals over 80 km standard single-mode fiber (SSMF) with bit-error rates (BERs) below the 20% soft-decision forward error correction (SD-FEC) threshold of 2.0×10-2. For wavelength division multiplexing (WDM) transmission, 8λ×150Gb/s PAM-4 signals spacing at 100 GHz can also achieve 80 km reach. Moreover, we compare the optical signal-to-noise ratio (OSNR) sensitivity with single sideband (SSB) scheme and evaluate the tolerance of bias deviation in numerical simulation. The proposed Alamouti coding-based scheme provides a hardware-efficient and dispersion-tolerant candidate for high-speed inter-data center interconnect (DCI) applications.

Validation of multispectral singlet oxygen luminescence dosimetry (MSOLD) for photofrin-mediated photodynamic therapy.

Accurate dosimetry is crucial for the ongoing development and clinical study of photodynamic therapy (PDT). Current dosimetry standards range from less accurate methods involving measurement of only light fluence and photosensitizer concentration during treatment, to significantly improved methods such as singlet oxygen explicit dosimetry (SOED), a macroscopic model that includes an additional important parameter in its dosimetric calculations: ground-state oxygen concentration ([3O2]). However, neither of these models is a method of direct dosimetry. Multispectral singlet oxygen luminescence dosimetry (MSOLD) shows promise in this regard but requires significant improvement in signal quality and remains to be validated in a clinical setting. In this study, we validate a linearly increasing MSOLD signal with an InGaAs photodiode detector for increasing concentration (0 mg/kg to 200 mg/kg) in tissue-simulating phantoms containing photofrin, calculating a calibration curve based on 1270 nm peak-intensity signal and area under the curve for background-subtracted singlet oxygen emission. Additionally, we validate MSOLD against the current clinical dosimetry standard, SOED, through simultaneous measurement of SOED parameters and MSOLD signal for varying concentrations (50 μM - 300 μM). Finally, we investigate the effects of using very high gain amplification on InGaAs photodiode detectors to amplify the MSOLD signal for use in clinical models. We show that a calibration curve relating photosensitizer concentration (PS) and MSOLD signal can be established. Additionally, we demonstrate good correlation between MSOLD signal and SOED-calculated [1O2]rx. However, we show that when using high amplification on InGaAs photodiodes for long illumination times, the inherent instability in these detectors becomes apparent.

Optical absorption spectroscopy of reactive oxygen and nitrogen species in a surface dielectric barrier discharge

A twin surface dielectric barrier discharge (SDBD) ignited in a dry synthetic air gas stream is studied regarding the formation of reactive oxygen and nitrogen species (RONS) and their impact on the conversion of admixed n-butane. The discharge is driven by a damped sinusoidal voltage waveform at peak-to-peak amplitudes of 8 kVpp–13 kVpp and pulse repetition frequencies of 250 Hz–4000 Hz. Absolute densities of O3, NO2, NO3, as well as estimates of the sum of the densities of N2O4 and N2O5 are determined temporally resolved by means of optical absorption spectroscopy using a laser driven broadband light source, suitable interference filters, and a photodiode detector. The measured densities are acquired across the center of the reactor chamber as well as at the outlet of the chamber. The temporal and spatial evolution of the species’ densities is correlated to the conversion of n-butane at concentrations of 50 ppm and 400 ppm, measured by means of flame ionization detectors. The n-butane is admixed either before or after the reactor chamber, in order to separate the impact of short- and long-lived reactive species on the conversion process. It is found that, despite the stationary conversion at the selected operating points, at higher voltages and repetition frequencies the densities of the measured species are not in steady state. Based on the produced results it is presumed that the presence of n-butane modifies the formation and consumption pathways of O3. At the same time, there is no significant impact on the formation of dinitrogen oxides (N2O4 and N2O5). Furthermore, a comparatively high conversion of n-butane, when admixed at the outlet of the reactor chamber is observed. These findings are discussed together with known rate coefficients for the reactions of n-butane with selected RONS.

In-depth characterization of phenolic profiling of Moraiolo extra-virgin olive oil extract and initial investigation of the inhibitory effect on Indoleamine-2,3-Dioxygenase (IDO1) enzyme

In this research, the phenolic extract from Moraiolo extra-virgin olive oil (EVOO) was thoroughly characterized. A reversed-phase HPLC method with a photodiode detector allowed to measure a total phenol content higher than 500 mg/kg EVOO, with elevated amounts of oleocanthal, oleacein, and oleouropein aglycone (131.2, 213.5, and 158.4 mg/kg EVOO, respectively). Appreciable amounts of (+)-pinoresinol and (+)− 1-acetoxy-pinoresinol, 3.2 and 12.5 mg/kg EVOO respectively, were measured. High-resolution mass spectrometry with Orbitrap mass analyzer technology was used to confirm the identity of the analytes. Afterwards, the extract was tested, for the first time, for its activity on Indoleamine-2,3-Dioxygenase (IDO1). This enzyme appears as a promising target for the modulation of the neuroinflammatory-oxidative processes relying on the pathogenesis of several neurodegenerative diseases. The extract showed an inhibitory effect on the catalytic activity of both human and murine IDO1, with a good safety at the concentrations of 15 and 30 µg/mL.

Optimization of ultrasonic-assisted extraction for bioactive compounds in Rubus ellipticus fruits: An important source for nutraceutical and functional foods

Bioactive compounds of Rubus ellipticus fruits are known for their potential in nutraceutical and functional food; however, systematic investigation on optimization of extraction conditions for improving yield is lacking. In the present study, extraction of bioactive compounds was performed using Plackett-Burman (PBD) and Central Composite Design (CCD). Parameters such as solvent to sample ratio, methanol concentration, and extraction temperature significantly (p < 0.05 and p < 0.001) influenced bioactive compounds extraction under linear, quadratic and interactive effects. The model predicted values of bioactive compounds and antioxidant activity were found close to the experimental value signifying the least coefficient of variation. Further, regression analysis showed a high coefficient of determination (R2) and a non-significant lack of fit. High-performance liquid chromatography equipped with a photodiode detector (HPLC- PDA) analysis detected the presence of seven bioactive compounds under optimal extraction conditions, among which catechin was maximum (27.67 mg/g DW). Results showed 35–99 percent improvement in yield to conventional studies and earlier reports on the species. The optimized process can further be upscaled for harnessing maximum benefits of the species in nutraceutical and energy supplement development program at an industrial scale.

An Energy-Efficient Wearable Functional Near-infrared Spectroscopy System Employing Dual-level Adaptive Sampling Technique.

Functional near-infrared spectroscopy (fNIRS) is a powerful medical imaging tool in brain science and psychology, it can also be employed in brain-computer interface (BCI) due to its noninvasive and artifact-less-sensitive characteristics. Conventional ways to detect large-area brain activity using near-infrared (NIR) technology are based on Time-division or Frequency-division modulation technique, which traverses all physical sensory channels in a specific period. To achieve higher imaging resolution or brain-tasks classification accuracy, the NIRS system require higher density and more channels, which conflict with the limited battery capacity. Inspired by the functional atlas of the human brain, this paper proposes a spatial adaptive sampling (SAS) method. It can change the active channel pattern of the fNIRS system to match with the real-time brain activity, to increase the energy efficiency without significant reduction on the brain imaging quality or the accuracy of brain activity classification. Therefore, the number of the averaging enabled channels will be dramatically reduced in practice. To verify the proposed SAS technique, a wearable and flexible NIRS system has been implemented, in which each channel of light-emitting diode (LED) drive circuits and photodiode (PD) detection circuits can be power gated independently. Brain task experiments have been conducted to validate the proposed method, the power consumption of the LED drive module is reduced by 46.58% compared to that without SAS technology while maintaining an average brain imaging PSNR (Peak Signal to Noise Ratio) of 35 dB. The brain-task classification accuracy is 80.47%, which has a 2.67% reduction compared to that without the SAS technique.

An InGaN/SiNx/Si Uniband Diode Photodetector

A novel self‐powered InGaN/SiNx/Si uniband diode photodetector (PD) is introduced. The full band structure is first constructed from the transition of direct tunneling to Fowler‐Nordheim tunneling of holes through the ultrathin SiNx interlayer at forward bias in the dark. Basis is the alignment of the n‐InGaN conduction band with the p‐Si valence band at zero bias. Under illumination, the photocurrent, responsivity, and bandwidth for the self‐powered PD at zero bias indicate two distinct operation modes (i) for longer and (ii) for shorter wavelengths of incident light. The two modes involve (i) absorption in Si and electron tunneling through the SiNx interlayer and (ii) absorption in InGaN and hole transport across the SiNx interlayer. The noise is considerably larger in operation mode (i) than in operation mode (ii). This is attributed to the presence or absence of energy barriers for electron and hole transport in PD operation. Hence, noise is introduced as an independent parameter to discriminate between longer and shorter wavelength regions in dual‐wavelength photodetection.

Performance of CsI (Tl) photodiode with optic fiber wire for Gamma-rays and X-rays detection

In this paper, we explored the feasibility study of using the optic fiber wire to be a light transmitter for crystal scintillation material in the radiation measurement. The high-density material; thallium doped cesium iodide CsI (Tl) are widely used as converters for Gamma-rays and X-rays into visible light. Optic fibers are applied in the various applications such nuclear facilities, future fusion installations, medical treatment and diagnostic premises etc. The major advantages to be considered in optic fibers for radiation detection because their characteristics such as: capacities to work under electromagnetic fields; possibility to carry the wavelength signals; small size and low mass including possibility to monitor parameters from the sites far away from the controller. In this work, the cylindrical crystal CsI (Tl) material was connected with the single-clad optic scintillating fiber which transmitted the light signal to photodiode. Gamma-rays and X-rays sources had been investigated the measurement. The optic scintillating fibers have a good response with Cs-137 gamma radiation source at 662 keV. X-ray radiation that was generated from the X-ray tube was determined with the different operating voltages. The obtained results show this device can measure the X-ray radiation with energy range from 39 to 309 keV. CsI (TI) photodiode detector with optic fiber wire can be applied to measure gamma radiation and X-ray radiation as well as being able to the further work in the nuclear and radiation fields.

BER Performance of UWOC With APD Receiver in Wide Range Oceanic Turbulence

In this paper, the bit error rate (BER) performance of underwater wireless optical communication (UWOC) systems with on-off keying (OOK) modulation and an avalanche photodiode (APD) detector are analyzed in a wide range of oceanic turbulence environment, such as lognormal, Gamma, K, Weibull, and Exponentiated Weibull distributions. To achieving this goal, a new mathematical system model is established, which has not only considered the aggregated degrading phenomena, namely the absorption, scattering, and turbulence, but also been suitable for describing UWOC with APD receiver. Then the closed-form expressions of the BER performances of UWOC with APD for different turbulence distributions are derived in detail by subdividing the working situation into high and lower inter-symbol interference (ISI) scenarios. Theoretical analysis and computer simulations show that no matter what the ISI levels are, the derived closed-form expressions for system BER under various turbulences can approximate the accurate integral ones well. This is obviously helpful to the design and performance evaluation of UWOC systems.

Direct injection green chromatographic method for simultaneous quantification of amoxicillin and amikacin in maternity hospital wastewater (Sagar, India)

Amoxicillin (AMO) and amikacin (AMK) are broad-spectrum antibiotics that are most preferably given post-delivery (normal and cesarian) in the maternity hospitals located in Sagar city (Madhya Pradesh), India. Both the antibiotics make their way through sewage/drainage systems into the environment in the form of metabolized and unmetabolized compounds. Growing concern about the contamination of wastewater by antibiotics requires fast, sensitive and eco-friendly techniques. Therefore a simple, rapid and environmental friendly chromatographic method has been developed for simultaneous determination of AMO and AMK in maternity hospital wastewater samples. A micellar liquid chromatographic (MLC) method was developed with a C18 column (250 mm × 4.6 mm), sodium dodecyl sulphate (SDS; 0.15 M), 1-butanol (7%) as a modifier, pH 5 and photo diode detector (PDA) at 270 nm and 256 nm for AMO and AMK respectively. The method was fast with analysis time below 9 min. In the present MLC method, linearities (r > 0.998), limits of quantification in the range of 0.02–0.04 μg/mL, repeatabilities, and intermediate precision below 4.9% were adequate for the quantification of AMO and AMK. The proposed method can be utilized to detect and quantify both the antibiotics in various samples by hospitals, pharmaceutical companies, pollution control board, municipal corporations, etc.

LIFGO: A modular laser-induced fluorescence detection system based on plug-in blocks

In this work, a laser-induced fluorescence (LIF) detection system built in a modular assembling mode was developed based on commercial LEGO blocks and 3D printed blocks. We designed and fabricated a variety of 3D printed building blocks fixed with optical components, including laser light source, filters, lens, dichroic mirror, photodiode detector, and control circuits. Utilizing the relatively high positioning precision of the plug-in blocks, a modular construction strategy was adopted using the flexible plug-in combination of the blocks to build a highly sensitive laser-induced fluorescence detection system, LIFGO. The LIFGO system has a simple structure which could be constructed by inexperienced users within 3 h. We optimized the structure and tested the performance of the LIFGO system, and its detection limits for sodium fluorescein solution in 100 μm i.d. and 250 μm i.d. capillaries were 7 nM and 0.9 nM, respectively. Based on the LIFGO system, we also built a simple capillary electrophoresis (CE) system and applied it to the analysis of DNA fragments to demonstrate its application possibility in biochemical analysis. The separation of 7 fragments in DL500 DNA markers were completed in 600 s. Because of the features of low cost (less than $100) and easy-to-build construction, we introduced the LIFGO system to the experimental teaching of instrumental analysis for undergraduate students. The modular construction form of the LIF detection system greatly reduces the threshold of instrument construction, which is conducive to the popularization of the LIF detection technique in routine laboratories as well as the reform of experimental teaching mode.

High accuracy indoor visible light positioning using a long short term memory-fully connected network based algorithm

In this work, a novel positioning algorithm based on a long short term memory-fully connected network (LSTM-FCN) is proposed to improve the performance of an indoor visible light positioning (VLP) system. Using the proposed LSTM-FCN based positioning algorithm, the VLP system with a single light emitting diode (LED) and multiple photodetectors (PDs) was implemented. On this basis, the positioning performance of the established VLP system using proposed LSTM-FCN, traditional FCN and support vector regression (SVR) based algorithm is investigated and compared. It is demonstrated that the VLP system using the proposed LSTM-FCN based algorithm has better performance than that using other machine learning algorithms. As a result, an average positioning error of 0.92 cm and a maximum positioning error of less than 5 cm can be obtained for the established VLP system.

Adaptive turbulence compensation and fast auto-alignment link for free-space optical communications.

Free-space point-to-point optical communication often suffers from atmospheric turbulence and device vibration where the environment is harsh. In this paper, by introducing an adaptive system composed of turbulence compensation and fast auto-alignment installation, we propose and experimentally demonstrate an optical communication system that is effective against turbulence and vibration. Turbulence compensation can increase the coupling efficiency by at least 3dB, while fast auto-alignment can reduce the spatial range of beam vibration caused by device vibration by 72.22%. Since the photodiode detector (PD) is sensitive to optical power, reducing the loss of the link improves the communication quality of the system. Bit-error rate (BER) of 10-Gbaud 16-ary quadrature amplitude modulation (16-QAM) signal transmission in the link is also measured under different transmitted power, having ∼8dB power penalty improvement with the adaptive system. In addition, turbulence compensation for higher-order modes such as optical vortex (OV) beams is also implemented, showing a promising prospect in space-division multiplexing (SDM) applications.

Laser blow-off with photodiode detection system at the helically symmetric experiment

A laser blow-off (LBO) system has been installed in the HSX stellarator to investigate impurity transport. A Nd:YAG laser is used to ablate a target area on a glass slide that has been coated with a thin film of aluminum and rapidly deposits a small, controlled quantity of aluminum atoms into HSX plasma. To study the radial propagation and confinement of the injected aluminum impurities, time-resolved emission measurements are made using a 20 channel AXUV photodiode detection system. The LBO system has achieved its design purpose, most notably the ability to make controlled impurity injection without significant perturbation to the background plasma. A detailed description of the setup as well as initial results of operation are presented.

Photodetector based on silicon-graphene heterojunction fabricated through rubbing-in technology

This article provides an insight into the fundamental physics of a rubbed-in graphene over silicon (Si) Schottky photodiode for its affordable applications in visible light and infrared (IR) irradiation. The graphene powder was deposited over the surface of boron-doped Si (p-Si) through rubbing-in (rolling-pressing) technology. The maximum reversed biased current observed was −75 microampere at −5 V and the rectifying ratio of 240 was obtained experimentally at 1 V. The current density-voltage characteristics of the p-Si-graphene junction were investigated, then samples were measured for its rectifying ratio and results showed the tendency of a photodiode detector to operate under IR and visible light regions. The device was saturated at the open-circuit voltage values of 15 mV for infrared and 1.8 mV for visible light, respectively. The surface morphology of the device was performed through scanning electron and atomic force microscopy. The reason behind the device performance has been studied considering its junction quality, low shunt resistance, bulk, and surface recombination mechanism which drastically may affect device performance. Hence, further layers and device optimization techniques were proposed to enhance photodiode performance. The study allows us to follow footsteps toward the fabrication of fast responsive, large-scale, and budget-friendly photodiode by using transfer-less and budget-free fabrication technology for proposing efficient photo-detectors on large scale as well as for educational purposes.

Effect of the APD Receiver’s Tilted Angle on Channel Capacity for Underwater Wireless Optical Communications

This paper focuses on investigating the effect of the receiver’s tilted angle on the channel capacity of an underwater wireless optical communication (UWOC) system, in which an avalanche photodiode (APD) detector is adopted as the receiver. Under the non-negativity, peak power, and average power constraints, the lower bounds on the capacity of UWOC are derived in detail according to different average-to-peak power ratios. With modeling achieving the maximum of the lower bounds of the capacity as an optimization object, we prove that the proposed optimization issue is in fact a simple convex optimization about the tilted angle of the APD receiver, and then present related theoretical solution for it. Both theoretical analysis and simulation results show that by appropriately tilting the receiver, we can significantly enhance the final capacity performance of the UWOC with APD receiver.

A New Design Protoype of Safety System on Traffic Light using Hydraulic Limiters Zebra Cross Automatic

Medan city is the third largest metropolitan city in Indonesia. Problems that occur in big cities, especially in the city of Medan itself, include the level of congestion and the level of violations of traffic signs which are quite high and the constraints of emergency vehicles on duty such as ambulances, fire engines and other emergency vehicles, especially on traffic lights. This paper described Emergency vehicles that will build a Security System Using Barriers on Zebra Crosses, especially in Microcontroller-Based Traffic Light. This system uses the RFID component RC522 as an emergency vehicle detector photodiode and laser diode as vehicle detection components above the zebra cross so that the barrier does not damage the vehicle. Servo motor as a barrier gate drive and Arduino Uno R3 as a component where each input command is received to be processed. Where if the emergency vehicle is passing through a traffic light with a red light, then the light will turn green. With this system, the emergency vehicle on duty is not late to its destination and the driver cannot break through the road divider when the red light is on and does not disturb pedestrians. feet to cross The application of the system is designed to be connected directly to Arduino so that the input signal can be processed and can produce the expected output on the performance of the system, namely the servo motor, and 6 LEDs on the traffic light 2 intersections.

Large Adaptive Optics Survey for Substellar Objects around Young, Nearby, Low-mass Stars with Robo-AO

Abstract We present results from the Large Adaptive optics Survey for Substellar Objects, where the goal is to directly image new substellar companions (&lt;70 M Jup) at wide orbital separations (≳50 au) around young (≲300 Myr), nearby (&lt;100 pc), low-mass (≈0.1–0.8 M ⊙ ) stars. We report on 427 young stars imaged in the visible (i′) and near-infrared (J or H ) simultaneously with Robo-AO on the Kitt Peak 2.1 m telescope and later the Maunakea University of Hawaii 2.2 m telescope. To undertake the observations, we commissioned a new infrared camera for Robo-AO that uses a low-noise high-speed SAPHIRA avalanche photodiode detector. We detected 121 companion candidates around 111 stars, of which 62 companions are physically associated based on Gaia DR2 parallaxes and proper motions, another 45 require follow-up observations to confirm physical association, and 14 are background objects. The companion separations range from 2 to 1101 au and reach contrast ratios of 7.7 mag in the near-infrared compared to the primary. The majority of confirmed and pending candidates are stellar companions, with ∼5 being potentially substellar and requiring follow-up observations for confirmation. We also detected a 43 ± 9 M Jup and an 81 ± 5 M Jup companion that were previously reported. We found 34 of our targets have acceleration measurements detected using Hipparcos–Gaia proper motions. Of those, 58 − 14 + 12 % of the 12 stars with imaged companion candidates have significant accelerations ( χ 2 &gt; 11.8 ), while only 23 − 6 + 11 % of the remaining 22 stars with no detected companion have significant accelerations. The significance of the acceleration decreases with increasing companion separation. These young accelerating low-mass stars with companions will eventually yield dynamical masses with future orbit monitoring.

A Custom Low-Noise Silicon Photodiode Detector Designed for Use With X-Ray Capillary Optics

We present the first results of a custom low-noise silicon photodiode detector designed for use with X-ray capillary optics. This system is intended to perform as a smaller, lighter, and low-powered alternative to currently existing X-ray telescope technologies. The detector has an active area with a diameter of 100 μm, and its small size leads to a low capacitance of well under 1 pF and a leakage current of 1 pA or less at the depletion voltage. We tested the detector with both a discrete preamp and an ultralow-noise front-end application-specific integrated circuit (ASIC). The front-end ASIC, developed at Brookhaven National Laboratory, was designed for low-capacitance detectors but had not been previously tested with a detector. Here, we discuss the detector design, the experimental setup, and the resulting detector performance. Using radioactive laboratory sources, we measure a full-width at half-maximum (FWHM) of 211 ± 8 eV at 5.9 keV with the ASIC and are able to set the threshold as low as 0.6 keV.