Variation Of Light Power Research Articles

Detection of preexisting quantum entanglements between dipole–photon discrete observables

We performed measurements of laser beam power polarized in different angles as 0^circ , 45^circ and 90^circ passing close to a symmetric shielded capacitor with parallel plates and through a polaroid filter configured with angles as 0^circ , 45^circ and 90^circ . An unusual light power variation was detected during the charging and discharging of the high voltage capacitor even considering the suppression of known electromagnetic interaction between laser beam and capacitor. The light power variation curves also indicated a typical pattern of charge and discharge of capacitors. The combination of the angles of the laser beam polarization and polaroid filter surprisingly indicated the measurement of correlations between the polarizations of photons and electric dipoles of the capacitor dielectric. These novel results can only be explained supposing the preexisting condition of quantum entanglements between discrete observables of electric dipoles and photons.

Modeling of photo-thermo-sensitive hydrogels by applying the temperature expansion analogy

Hydrogels are an outstanding material for sensor and actuator applications, for example, chemosensors and microfluidics, and have been extensively studied in both, experiments as well as in modeling within the last years. The theoretical investigations of hydrogels are key factors for the development of new hydrogel-based concepts in research and engineering. The recent approaches in modeling of the light-sensitive behavior of hydrogels are often complicated and very detailed. Commonly, they are based on the Helmholtz free energy function within a continuum-mechanical framework. In contrast, the Stimulus Expansion Model (SEM) is a simple and very effective approach to embed the swelling properties of a hydrogel into a continuum mechanical framework. Originally, the SEM was applied to chemical stimulation processes based on available experimental swelling curves. The current work provides an extension of the SEM for photo-thermo-sensitive hydrogels. The present approach considers (i) the attenuation of light by applying Lambert-Beer’s law as well as (ii) the energy transfer of light into heat. In this study, PNIPAm hydrogels with incorporated light-absorbing particles of copper-chlorophyllin are investigated. To demonstrate the capabilities of the presented approach, the effect of the variation of (i) light power, (ii) particle volume fraction, and (iii) ambient temperatures on the swelling behavior is analyzed. The obtained results show an excellent correlation with experimental results from literature. Concluding, the extended Stimulus Expansion Model provides further opportunities to design and simulate photo-thermo-sensitive hydrogels for engineering applications.

Optical duobinary transmitter based OQPSK line coding phase offset for the prediction of OWC channel systems performance efficiency

Abstract This work demonstrates the optical duobinary transmitter based optical quadature phase shift keying line coding phase offset for the prediction of optical fiber wireless channel systems performance efficiency. The max signal light power variations with the spectral wavelength variations for different degree phase offsets based optical quadrature phase shift keying (OQPSK) transmitter are clarified. The max signal light power variations with the time variations for various degrees phase offset based OQPSK transmitter are demonstrated. The total power lighted after OWC channel for various degree phase offset based OQPSK transmitter are indicated. The max electrical power signal amplitude variations with the time variations for various degree phase offset based OQPSK transmitter are observed. Total electrical power signal after optical receiver for various degree phase offset based OQPSK transmitter is clarified. Total optical power variations after OWC channel for various degrees phase offset based OQPSK transmitter is studied.

Extension of the stimulus expansion model for photo‐thermo‐sensitive hydrogels

AbstractThe stimulus expansion model uses the analogy of thermal expansion in order to model the mechanical swelling behavior of a polymer gel. In the current work, we present an approach to extend the stimulus expansion model for photo‐thermo‐sensitive hydrogels. We describe the swelling behavior by using the stimulus properties, in our case light, as input values and the volume change of the hydrogel as the result by physical coherences. Further, we consider the energy conversion from light into heat within the polymer gel, due to absorption by particles. This phenomenon is considered by an energy balance which depicts the energy input by applying Lambert‐Beer's law. for the absorption of light. By evaluating the energy balance, we can calculate the light dependent temperature increase of the thermo‐sensitive hydrogel. Afterwards, the hydrogel's swelling is modeled by using the thermal expansion analogy. This detailed description of the stimulus behavior allows to study a hydrogel composite without having specific experimental data for this certain combination, but for all the involved components. Furthermore, the time‐dependent stimulus behavior of the considered sample is shown. Based on this approach, the effect of light power variation, particle volume fraction variation and different ambient temperature is studied.

IoT-Based Automatic Home Light Monitoring System Using Wemos D1 Mini

This research aims to design an IoT-based home light monitoring system using Wemos D1 Mini. This tool is designed to control the current and voltage contained in house lights automatically. The sensor used to measure the current in the house lights is the ACS712 sensor, and the sensor used to measure the voltage in the house lights is the ZMPT101B sensor. The simulation of the house lights on this tool uses three LED lights, where each lamp is located on the terrace of the house, living room, and kitchen with different light power variations. In addition, the Blynk application on smartphones can be used to turn lights off and on and monitor currents and voltages. The test results show that this tool can control three regulated room lights and monitor the current and voltage in the three lights online using the Blynk application.

A genetic algorithm and backpropagation neural network based temperature compensation method of spin-exchange relaxation-free co-magnetometer.

This paper presents a temperature compensation method based on the genetic algorithm (GA) and backpropagation (BP) neural network to reduce the temperature induced error of the spin-exchange relaxation-free (SERF) co-magnetometer. The fluctuation of the cell temperature results in the variation of the optical rotation angle and the probe light absorption. The temperature fluctuation of the magnetic field shielding layer induces the variation of the magnetic field. In addition, one of the causes of light power variation is temperature fluctuation of the optical element. In summary, temperature fluctuations cause a variety of SERF co-magnetometer errors, and the relationship between these errors and temperature fluctuations has the characteristics of time-variance and non-linearity. There are two kinds of methods to suppress these errors. One way is to reduce temperature fluctuations of the SERF co-magnetometer. However, this method requires additional hardware and high cost, which are not suitable for miniaturization and low cost applications. Another effective method to suppress nonlinear and time-varying errors is to utilize intelligent algorithms for temperature compensation. In this paper, the BP neural network is applied for temperature compensation, and the GA is utilized to overcome the disadvantages of the BP neural network. The training data were obtained by changing the ambient temperature of the SERF co-magnetometer. The experimental results show that the method proposed in this work can significantly improve the accuracy of the co-magnetometer at complex ambient temperatures, and the stability of the SERF co-magnetometer at room temperature can be improved by at least 45%.

Multipoint dispersion spectroscopic gas sensing by optical FMCW interferometry.

We present a novel, to the best of our knowledge, multipoint gas-sensing method based on dispersion spectroscopy using optical frequency-modulated continuous-wave (FMCW) techniques. By taking advantage of the optical FMCW's excellent multiplexing capability with high spatial resolution, the phase noise in the retrieved dispersion signal is efficiently suppressed. As a proof of concept, this method is experimentally demonstrated with three acetylene gas-sensing nodes, achieving a sensitivity of 30 ppm, a sensing spatial resolution of 30 cm, and a linear dynamic range of more than 3 orders of magnitude. Having advantages of high sensitivity, high spatial resolution, large dynamic range, and immunity to light power variation, the proposed method promotes a novel way for the development of long-distance multipoint spectroscopic gas sensors.

Integrated role between VCSEL diodes and Gaussian pulse generators with ideal EDFA for self phase modulation instability management

Abstract This work outlined the integrated role between vertical cavity surface emitting laser diodes with Gaussian pulse generators and Ideal erbium doped fiber amplifier (EDFA) for the self-phase modulation instability management, as well as the signal/NP level (Power level [PL]) with the spectral frequency is simulated after wavelength division multiplexing (WDM) fiber at length of 10 km based third order Gaussian pulse generators. The light power variations against temperature after WDM fiber is also studied at length of 10 km based various order Gaussian pulse generators. Electrical received power (ERP) variations against temperature is clarified after avalanche photo diode (APD) photodetectors based various order Gaussian pulse generators. The study emphasis the bad effects of the increase of the temperature, and higher Gaussian pulse generators order on the signal power levels.

Compact omnidirectional multicore fiber-based vector bending sensor

We propose and demonstrate a compact and simple vector bending sensor capable of distinguishing any direction and amplitude with high accuracy. The sensor consists of a short segment of asymmetric multicore fiber (MCF) fusion spliced to a standard single mode fiber. The reflection spectrum of such a structure shifts and shrinks in specific manners depending on the direction in which the MCF is bent. By monitoring simultaneously wavelength shift and light power variations, the amplitude and bend direction of the MCF can be unmistakably measured in any orientation, from 0° to 360°. The bending sensor proposed here is highly sensitive even for small bending angles (below 1°).

Highly sensitive multicore fiber accelerometer for low frequency vibration sensing

We report on a compact, highly sensitive all-fiber accelerometer suitable for low frequency and low amplitude vibration sensing. The sensing elements in the device are two short segments of strongly coupled asymmetric multicore fiber (MCF) fusion spliced at 180° with respect to each other. Such segments of MCF are sandwiched between standard single mode fibers. The reflection spectrum of the device exhibits a narrow spectrum whose height and position in wavelength changes when it is subjected to vibrations. The interrogation of the accelerometer was carried out by a spectrometer and a photodetector to measure simultaneously wavelength shift and light power variations. The device was subjected to a wide range of vibration frequencies, from 1 mHz to 30 Hz, and accelerations from 0.76 mg to 29.64 mg, and performed linearly, with a sensitivity of 2.213 nW/mg. Therefore, we believe the accelerometer reported here may represent an alternative to existing electronic and optical accelerometers, especially for low frequency and amplitude vibrations, thanks to its compactness, simplicity, cost-effectiveness, implementation easiness and high sensitivity.

An auto-correction laser photoacoustic spectrometer based on 2f/1f wavelength modulation spectroscopy.

An auto-correction laser photoacoustic (PA) spectrometer based on 2f/1f wavelength modulation spectroscopy (WMS) has been proposed and demonstrated for trace gas detection to eliminate concentration measurement errors due to light power variations. A 1.53 μm distributed feedback (DFB) laser is used as a light source to excite the 2f PA signal that is generated by gas absorption. Meanwhile, a multilayer graphene sheet is employed as a highly efficient photothermal conversion unit for adding a 1f PA background signal, whose amplitude at the absorption center of the traditional PAS system is almost zero. The experimental results show that the gas concentration measured from the 2f/1f WMS signal is almost independent of the laser power. A detection limit of 416 ppb has been achieved for the 1 s measurement interval and could be further improved to 65 ppb with 100 s averaging, according to the Allan deviation analysis.

Overlap Spectrum Fiber Bragg Grating Sensor Based on Light Power Demodulation.

Demodulation is a bottleneck for applications involving fiber Bragg gratings (FBGs). An overlap spectrum FBG sensor based on a light power demodulation method is presented in this paper. The demodulation method uses two chirp FBGs (cFBGs) of which the reflection spectra partially overlap each other. The light power variation of the overlap spectrum can be linked to changes in the measurand, and the sensor function can be realized via this relationship. A temperature experiment showed that the relationship between the overlap power spectrum of the FBG sensor and temperature had good linearity and agreed with the theoretical analysis.

Self-Referenced Broad-Range Optical Rotation Sensor for Flight Control Applications

In this paper, we present a self-referenced broad range optical rotary sensor (ORS) for avionics applications. To achieve the high reliability required for aerospace use, the rotary encoder operates ratiometrically to make it insensitive to source light power variation. This sensor has a higher operating range than rotary variable differential transformers (RVDTs) currently used in fly-by-wire aircraft. The ORS encoder is fabricated on an antireflection coated glass substrate with a reflective aluminum coating. Experimental results prove that the sensor accuracy is 0.8% over the full rotation range from 0° to 356.5°. The proposed ORS has better accuracy and an operating range of at least twice that of RVDTs, which have an accuracy of 1% over a full range of only 80°. We also test the insensitivity of the sensor to source fluctuations, which confirms that the sensor is self-referencing.

Compensation technique for environmental and light source power variations applied in a polymer optical fiber curvature sensor for wearable devices

Abstract Introduction Polymer optical fibers (POF) are lightweight, present high elastic strain limits, fracture toughness, flexibility in bend, and are not influenced by electromagnetic fields. These characteristics enable the application of POF as curvature sensor and can overcome the limitations of the conventional technologies, especially for wearable and soft robotics devices. Nevertheless, POF based curvature sensors can suffer from environmental and light source power deviations. This paper presents a compensation technique for the environmental and light source power deviations in a POF curvature sensor. Methods The curvature sensor was submitted to variations of temperature, humidity and light source power to characterize the sensor response and evaluate the proposed compensation technique. In addition, tests with the simultaneous variation of the angle and light source power variation were performed. Results Results show that temperature and humidity effects do not lead to significative errors on the sensor measurement for wearable devices application, where a hardware-based compact and portable compensation technique of the light source deviation is applied. Moreover, the sensor with the compensation technique developed is compared with a potentiometer for dynamic measurements and the root-mean-square error of about 1° is obtained, which is lower than sensors based on similar operation principle presented in the literature and some commercially available devices. Conclusions The compensation technique proposed was able to compensate power deviations applied and resulted in a sensor with low errors with the additional advantages of compactness and low-cost, which enable its application as wearable sensors and on the instrumentation of wearable robots.

MoS2-based all-fiber humidity sensor for monitoring human breath with fast response and recovery

A humidity sensor is demonstrated using a MoS2-coated etched single-mode fiber (ESMF) and applied in human breath monitoring. Because of the interaction between MoS2 nanosheets and the evanescent field of an ESMF, the light confined within fiber core could be tuned by ambient conditions. The optical frequency conductivity of MoS2 changes with relative humidity variation, so does the transmission light power of the ESMF. A 14 fold enhancement of light power variation in response to human breaths is achieved compared with a bare ESMF. Fast response and recovery speed (0.066s response and 2.395s recovery time) enable this sensor to detect human breath in real time. The results also show the feasibility in monitoring different breath patterns related to the breath frequency and depth.

Differential measurements of light power variations through Si photodiodes in a bridge configuration for high-sensitivity chemical/biological optical sensing

This paper reports on a new optoelectronic technique based on the differential measurement of currents for the detection of small variations of the molar concentrations of chemical and biological substances by measuring changes of light power through two Si-photodiodes used in a bridge configuration. The solution exhibits high sensitivity, linear response and allows for the compensation of the initial bridge unbalance without changing its elements so optimising the output signal amplification and detection resolution. The proposed optoelectronic approach allows obtaining unique performances with respect to those ones achievable by using the standard synchronous demodulation technique for amplitude and phase measurements implemented by lock-in amplifiers. Moreover, the overall optoelectronic apparatus is simple and suitable for portable integrated sensor systems. Its main performances have been experimentally evaluated through a prototype PCB employing off-the-shelf components demonstrating the capability to detect light power variations with a settable maximum sensitivity of 300mV/nW with a resolution of about 3pW. Furthermore, a comparison with amplitude measurements based on the standard synchronous demodulation technique performed by lock-in amplifiers has demonstrated that the proposed optoelectronic system allows for a sensitivity enhancement of 2.9×104. As a case example, the optoelectronic system has been employed to determine variations of the molar concentration of a Rhodamine B solution diluted in ethanol with a resolution of about 5pM by performing optical absorption measurements.

Current-Based High-Sensitivity Differential Detection of Light Power Using Si Photodiodes in Bridge Configuration for Chemical/Biological Optical Sensing

We present a new optoelectronic technique based on the differential measurement of currents for the detection of the variations of low concentrations of chemical and biological substances by measuring light power absorption through two Si-photodiodes (SiPD) in a bridge configuration. The solution exhibits high sensitivity, linear response and allows the compensation of the initial bridge unbalance without changing its elements so optimising signal amplification gain and detection resolution. The technique shows unique performances with respect to voltage amplitude measurements performed by lock-in amplifiers. Moreover, the experimental apparatus is simple and suitable for portable integrated sensor systems. Its main performances have been evaluated through a prototype PCB demonstrating the capability to detect light power variations with a settable maximum sensitivity of 30mV/nW and a resolution of 33pW.

High-Sensitivity High-Resolution Optical Phase Shift Detection Technique Using a Si Photodiode Operating in Photovoltaic Mode

In this paper, we report the optimization of the operating conditions and the maximization of the performances of the phase shift detection technique allowing to approach the best sensitivity and resolution in terms of light power variations. The system is based on the synchronous demodulation technique and uses a Si photodiode operating in photovoltaic mode biased through a small amplitude sinusoidal modulating signal. Employing a commercial lock-in amplifier for phase measurements and varying the signal modulating frequency, we prove that it is possible to obtain the maximum theoretical phase shift variation range equal to 90° with a resulting sensitivity and resolution equal to 3100°/ $\mu \text{W}$ and 3 pW, respectively. We demonstrate that these results are more than two orders of magnitude greater than those ones achievable by employing a Si photodiode in photoconductive mode. As a case-example for chemical applications, we apply the proposed technique to detect the variations of the molar concentration of a methylene blue solution by measuring the variations of the transmittance of a laser beam passing through the substance. The experimental findings are compared with those ones achieved by using a commercial spectrophotometer and the conventional amplitude detection technique employing the lock-in amplifier. Despite the achieved results are limited by the fixed phase resolution of the employed lock-in amplifier, here, the proposed approach allows to measure molar concentration variations with a resolution of 79 pM resulting 1354 times higher than that one obtained using the spectrophotometer and 33 times better than the value achieved with the amplitude detection technique.

Very high‐sensitivity tunable phase detection of light power variations using electrical modulation of Si‐photodiode in photovoltaic regime

The use of a silicon (Si)-photodiode (Si-PD) operating in photovoltaic mode as a tunable very high-sensitivity phase detector of light power variations is demonstrated. This result is reached by applying to the Si-PD an electrical modulation through an AC excitation signal without a DC reverse bias. This allows employing the synchronous demodulation technique for phase detection that shows much better performances with respect to the conventional amplitude measurements, mainly overcoming the issues related to the electrical noise and the resolution limitation due to the selected full scale. The phase variations to be detected occur between the modulating signal and the one provided by the Si-PD as a function of the light power variations on its sensitive area. The proposed approach notably simplifies both the electronic circuitry and the optical setup, minimising the detection system complexity and size. Experimental results demonstrate that it is possible to achieve phase detection sensitivity, with respect to light power variations, of up to 410°/μW as a function of the Si-PD settable operating conditions. Using a standard commercial lock-in amplifier with a 0.01° phase resolution is possible to obtain a light power resolution of up to 25 pW.

Optical Measurements by Phase Shift Based Technique for High Sensitivity and High Resolution Detection of Chemical/Biological Substances

In this work we demonstrate that the phase shift detection technique can be applied to reveal, with very high sensitivity and resolution, concentrations of chemical/biological substances optically detectable by measuring power variations of a light source. The system is based on the synchronous demodulation technique and employs a Si photodiode (PD) operating in photovoltaic regime biased through a small modulating sinusoidal waveform. The phase shift variations are measured between this biasing voltage and that one generated by the Si PD illuminated by the light, that interacts with the chemical/biological sample under analysis, providing the phase shift change. Experimental results demonstrate that is possible to achieve phase detection sensitivity, with respect to light power variations, up to 3100°/μW as a function of the Si PD settable operating conditions. By using a commercial lock-in amplifier with a 0.01° phase resolution, a light power variation resolution of about 3pW has been achieved. As a case-example, variations of the molar concentration of a methylene blue solution are detected by performing optical absorption standard measurements. Despite the phase resolution limitation of the used lock-in amplifier, the comparison between the data obtained through the proposed technique and those ones achieved by conventional amplitude measurements demonstrates a high improvement of the detection sensitivity. As a consequence, the measurement of molar concentration variations with a resolution of 80pM is achieved resulting 33 times higher than that one obtained with the amplitude detection.