Calibration of Automatic Sun Photometer with Temperature Correction in Field Environment

Aerosol optical depth (AOD) is an important atmospheric correction parameter in remote sensing. In order to obtain AOD accurately, the surface-based automatic sun photometer needs to carry out calibration regularly. The normally used Langley method can be effective only when the AOD and the calibration coefficients of the instrument remain unchanged throughout the day. However, when observing the AOD with CE318 sun photometer in field environment, it was found that the AOD of silicon (Si) detector at 1020 nm and indium gallium arsenide (InGaAs) detector at 1639 nm was strongly influenced by temperature due to the large temperature difference at the Dunhuang site. Based on the corresponding relationship between AOD and wavelength, the model of the calibration coefficients varying with temperature was established by nonlinear regression method in field environment. By comparing the AOD before and after temperature correction with the theoretical one, the ratio of data with relative error (RE) less than 5% increased from 0.195 and 0.14 to 0.894 and 0.355, respectively. By this method, calibration can be carried out without the limit of constant AOD. In addition, it is simpler, more convenient, and less costly to perform temperature correction in a field environment than in a laboratory.

Simulation and analysis of a Single Mode Indium Gallium Arsenide Phosphide Vertical Cavity Surface Emitting Laser for Optical Communication

This present work is about simulating and analysing a Vertical Cavity Surface Emitting Laser (VCSEL) structure used in optical fibre communication systems. In this paper a VCSEL structure made of seven Quantum Wells of Indium Gallium Arsenide Phosphide (InGaAsP) emitting at 1550 nm is simulated. The device is analysed looking at the following characteristics: Direct current current and voltage (IV) characteristics, light power against electrical bias, optical gain against electrical bias, light distribution over the structure, output power and threshold current. Specification of material characteristics, ordinary physical models settings, initial VCSEL biasing, mesh declarations, declaration of laser physical models, their optical and electrical parameters were defined using Atlas syntax. Mirror ratings and quantum wells are the two main parameters that were studied and analysed to come up with structure trends. By determining important device parameters such as proper selection of the emission wavelength and choice of material; a VCSEL with an output power of 9.5 mW was simulated and compared with other structures.

Towards single-chip radiofrequency signal processing via acoustoelectric electron–phonon interactions

The addition of active, nonlinear, and nonreciprocal functionalities to passive piezoelectric acoustic wave technologies could enable all-acoustic and therefore ultra-compact radiofrequency signal processors. Toward this goal, we present a heterogeneously integrated acoustoelectric material platform consisting of a 50 nm indium gallium arsenide epitaxial semiconductor film in direct contact with a 41° YX lithium niobate piezoelectric substrate. We then demonstrate three of the main components of an all-acoustic radiofrequency signal processor: passive delay line filters, amplifiers, and circulators. Heterogeneous integration allows for simultaneous, independent optimization of the piezoelectric-acoustic and electronic properties, leading to the highest performing surface acoustic wave amplifiers ever developed in terms of gain per unit length and DC power dissipation, as well as the first-ever demonstrated acoustoelectric circulator with an isolation of 46 dB with a pulsed DC bias. Finally, we describe how the remaining components of an all-acoustic radiofrequency signal processor are an extension of this work.

Effect of Surface Oxidation on the Material Loss of InGaAs in Acidic Solutions

Indium gallium arsenide (InGaAs) is one of the candidate materials to overcome the physical limitation of Si due to its excellent electrical properties. The effect of surface oxidation on the etching characteristics of InGaAs surface in acidic solutions were investigated. InGaAs surfaces was etched in HCl/H2O2/H2O (CPM) and HNO3/H2O2/H2O (NPM), while there was no thickness change in diluted HCl or HNO3. The CPM-treated InGaAs surface had a lower etching rate than the NPM-treated one, while etching rate of oxidized layer was higher in diluted HCl than in HNO3. NaCl added in the NPM acts as an etching inhibitor for InGaAs and the etching rate was significantly suppressed. It is thought that Cl− anion inhibits the formation of hydroxyl radical (OH∙) or consumes OH∙ in acidic solution, inhibiting surface oxidation of InGaAs and suppressing its material loss.

Silicon-Germanium Dioxide and Aluminum Indium Gallium Arsenide-Based Acoustic Optic Modulators

The purpose of this study was to clarify the silicon-germanium dioxide (SiGeO2) and Aluminum Indium Gallium Arsenide (AlInGaAs) based acoustic optic modulators for upgrading transmission performance characteristics. The transient time response of these modulators is analyzed and discussed in detail. The 3-dB modulation signal bandwidth, diffraction signal efficiency, signal rise time, and signal quality factor with minimum data error rates are also considered. The proposed models with silicon-germanium dioxide and Aluminum Indium Gallium Arsenide acoustic optic modulators were compared to the previous model with silicon acoustic optic modulators. The results confirmed the high-performance efficiency of the proposed models when compared to the previous model, in both the lowest transient time response and the highest acoustic optic modulators speed response.

Ground-based FTIR O₃ retrievals from the 3040 cm⁻¹ spectral range at Xianghe, China

In this study, we present O3 retrievals from ground-based Fourier-transform infrared (FTIR) solar absorption measurements between June 2018 and December 2019 at Xianghe, China (39.75° N, 116.96° E). The FTIR spectrometer at Xianghe is operated with indium gallium arsenide (InGaAs) and indium antimonide (InSb) detectors, recording the spectra between 1800 and 11000 cm−1. As the harmonized FTIR O3 retrieval strategy (Vigouroux et al., 2015) within the Network for the Detection of Atmospheric Composition Change (NDACC) uses the 1000 cm−1 spectral range, we designed an alternative O3 retrieval strategy in the 3040 cm−1 spectral range at Xianghe. The retrieved O3 profile is mainly sensitive to the vertical range between 5 and 40 km, and the degree of freedom for signal is 2.4 ± 0.3 (1σ), indicating that there are two individual pieces of information in partial columns between the surface and 20 km and between 20 and 40 km. According to the optimal estimation method, the systematic and random uncertainties of the FTIR O3 total columns are about 13.6 % and 1.4 %, respectively. The random uncertainty is consistent with the observed daily standard deviation of the FTIR retrievals. To validate the FTIR O3 total and partial columns, we apply the same O3 retrieval strategy at Maïdo, Reunion Island (21.08° N, 55.38° E). The FTIR O3 (3040 cm−1) measurements at Xianghe and Maïdo are then compared with the nearby ozonesondes at Beijing (39.81° N, 116.47° E) and at Gillot (20.89° S, 55.53° E), respectively, as well as with co-located TROPOspheric Monitoring Instrument (TROPOMI) satellite measurements at both sites. In addition, at Maïdo, we compare the FTIR O3 (3040 cm−1) retrievals with the standard NDACC FTIR O3 measurements using the 1000 cm−1 spectral range. It is found that the total columns retrieved from the FTIR O3 3040 cm−1 measurements are underestimated by 5.5–9.0 %, which is mainly due to the systematic uncertainty in the partial column between 20 and 40 km (about −10.4 %). The systematic uncertainty in the partial column between surface and 20 km is relatively small (within 2.4 %). By comparison with other measurements, it is found that the FTIR O3 (3040 cm−1) retrievals capture very well the seasonal and synoptic variations of the O3 total and two partial columns. Therefore, the ongoing FTIR measurements at Xianghe can provide useful information on the O3 variations and (in the future) long-term trends.

Plasmonic electro-optic modulator based on degenerate semiconductor interfaces

We present a semiconductor-based optoelectronic switch based on active modulation of surface plasmon polaritons (SPPs) at lattice-matched indium gallium arsenide (In0.53Ga0.47As) degenerately doped pn++ junctions. The experimental device, which we refer to as a surface plasmon polariton diode (SPPD), is characterized electrically and optically, showing far-field reflectivity modulation for mid-IR wavelengths. Self-consistent electro-optic multiphysics simulations of the device’s electrical and electromagnetic response have been performed to estimate bias-dependent modulation and switching times. The numerical model shows a strong agreement with the experimental results, validating the claim of excitation and modulation of SPPs at the junction, thus potentially providing a new pathway toward fast optoelectronic devices.

Эпитаксиальные квантовые точки InGaAs в матрице Al-=SUB=-0.29-=/SUB=-Ga-=SUB=-0.71-=/SUB=-As: интенсивность и кинетика люминесценции в ближнем поле серебряных наночастиц

Quantum dots of indium gallium arsenide buried in a thin layer of aluminum gallium arsenide were grown by means of molecular-beam epitaxy. The influence of silver nanoparticles grown on the surface of the semiconductor structure by vacuum thermal evaporation on photoluminescence of quantum dots was investigated. Photoluminescence spectra of quantum dots were obtained under stationary and pulsed excitation. The influence of silver nanoparticles exhibiting plasmon resonances on spectral distribution and kinetics of luminescence of the epitaxial quantum dots was studied.