InGaAs Diode Research Articles

Spectral current density and responsivity scaling for Fourier transform photocurrent spectroscopy.

We propose and experimentally verify a methodology to scale arbitrary units to photocurrent spectral density (A/eV) in Fourier transform Photocurrent (FTPC) spectroscopy. We also propose the FTPC scaling to responsivity (A/W), provided a narrow-band optical power measurement is available. The methodology is based on an interferogram waveform consisting of a constant background and interference contribution. We also formulate conditions that have to be met for correct scaling. We experimentally demonstrate the technique on a calibrated InGaAs diode and weak responsivity, long response time SiC interdigital detector. We identify a series of impurity-band and interband transitions in the SiC detector and slow mid-gap to conduction band transitions.

Effect of photobiomodulation on external root resorption during orthodontic tooth movement – a randomized controlled trial

The objective of the study was to compare external root resorption during orthodontic tooth movement between patients who were subjected to photobiomodulation and those who were not. The study was designed as a split-mouth, single-blind randomized controlled trial conducted on twenty-two orthodontic patients requiring extraction of maxillary first premolars (age group 13-30years). A buccal force was applied to all the premolars using a 0.019″×0.025″ beta-titanium cantilever spring for 28days. The test group premolars were irradiated by indium-gallium-arsenide (InGaAs) diode laser (980nm, 100mW) 0, 3, 7, 11, 15 and 28days after force application. Each premolar was irradiated at ten locations on the buccal and palatal gingiva resulting in a total energy of 10J delivered per tooth. After 28days, the root surface of all the premolars were studied for the number and volume of resorption craters using three-dimensional optical profilometry by a blinded assessor. One-sample Kolmogorov-Smirnov test was used to ascertain normality and Mann-Whitney U test was applied for data analysis. All twenty-two patients enrolled completed the study. The root surface analysis showed formation of 32.78% less number of resorption craters (P<0.05) and 39.49% less volume of resorption craters (P<0.05) in the test group premolars relative to the control group premolars. The results of the present study, therefore, suggest that photobiomodulation reduces external root resorption during orthodontic tooth movement. CTRI/2018/04/013520.

The branching ratio of intercombination [formula omitted]transitions in the RbCs molecule: Measurements and calculations

We observed the A1Σ+∼b3Π→a3Σ+/X1Σ+laser-induced fluorescence (LIF) of the RbCs molecule excited from the ground X1Σ+state by the Ti:Sapphire laser. The LIF spectra from the common perturbed levels of the singlet-triplet A ∼ b complex was recorded by the Fourier-transform (FT) spectrometer with the instrumental resolution of 0.03 cm−1. The relative intensity distribution in the rotationally resolved A∼b→a3Σ+(va)/X1Σ+(vX)progressions was measured, and their branching ratio was found to be about of 1÷5×10−4in the bound region of the a3Σ+and X1Σ+states. The experiment was complemented with the scalar- and full-relativistic calculations of the A/b−X/atransition dipole moments (TDMs) as functions of internuclear distance. The relative systematic error in the resulting ab initio TDM functions evaluated for the strong A−Xtransition was estimated as few percent in the energy region, where the experimental LIF intensities are relevant. The relative spectral sensitivity of the FT registration system, operated with the InGaAs diode detector and CaF beam-splitter, was calibrated in the range [6 500, 12 000] cm−1by a comparison of experimental intensities in the long A ∼ b → X(vX) LIF progressions of the K2 and KCs molecules with their theoretical counterparts evaluated using the ab initioA−XTDMs. Both experimental and theoretical transition probabilities can be employed to improve the stimulated Raman adiabatic passage process, a → A ∼ b → X, which is exploited for a laser assembling of ultracold RbCs molecules.

Miniature Broadband NIR Spectrometer Based on FR4 Electromagnetic Scanning Micro-Grating.

This paper presents a miniaturized, broadband near-infrared (NIR) spectrometer with a flame-retardant 4 (FR4)-based scanning micrograte. A 90° off-axis parabolic mirror and a crossed Czerny–Turner structure were used for creating an astigmatism-free optical system design. The optical system of the spectrometer consists of a 90° off-axis parabolic mirror, an FR4-based scanning micrograte, and a two-color indium gallium arsenide (InGaAs) diode with a crossed Czerny–Turner structure optical design. We used a wide exit slit and an off-axis parabolic mirror with a short focal length to improve the signal-to-noise ratio (SNR) of the full spectrum. We enabled a miniaturized design for the spectrometer by utilizing a novel FR4 micrograte for spectral dispersion and spatial scanning. The spectrometer can detect the full near-infrared spectrum while only using a two-color InGaAs diode, and thus, the grating scanning angle of this spectrometer is small when compared to a dual-detector-based spectrometer. In addition, the angle signal can be obtained through an angle sensor, which is integrated into the scanning micrograte. The real-time angle signal is used to form a closed-loop control over the scanning micrograte and calibrate the spectral signal. Finally, a series of tests was performed. The experimental results showed that the spectrometer has a working wavelength range of 800–2500 nm. The resolution is 10 nm at a wavelength range of 800–1650 nm and 15 nm at a wavelength range of 1650–2500 nm. Similarly, the stability of these two wavelength ranges is better than ±1 nm and ±2 nm, respectively. The spectrometer’s volume is 80 × 75 × 65 mm3 and its weight is 0.5 kg. The maximum spectral fluctuation does not exceed 1.5% and the signal-to-noise ratio is 284 after only one instance of averaging.

Miniaturized NIR Spectrometer Based on Novel MOEMS Scanning Tilted Grating.

This paper presents a dispersive near-infrared spectrometer with features of miniaturization, portability and low cost. The application of a resonantly-driven scanning grating mirror (SGM) as a dispersive element in a crossed Czerny–Turner configuration enables the design of a miniaturized spectrometer that can detect the full spectra using only one single InGaAs diode. In addition, a high accuracy recalculation is realized, which can convert time-dependent measurements to spectrum information by utilizing the deflection position detector integrated on SGM and its associated closed-loop control circuit. Finally, the spectrometer prototype is subjected to a series of tests to characterize the instrument’s performance fully. The results of the experiment show that the spectrometer works in a spectral range of 800 nm–1800 nm with a resolution of less than 10 nm, a size of 9 × 7 × 7 cm3, a wavelength stability better than ±1 nm and a measuring time of less than 1 ms. Furthermore, the power consumption of the instrument is 3 W at 5 V DC, and the signal-to-noise ratio is 3267 at full scale. Therefore, this spectrometer could be a potential alternative to classical spectrometers in process control applications or could be used as a portable or airborne spectroscopic sensor.

Transparent glass–ceramics with (Eu3+,Yb3+):YNbO4 nanocrystals: Crystallization, structure, optical spectroscopy and cooperative upconversion

In the present work, we report on a comprehensive study of crystallization, structure and optical spectroscopy of transparent glass–ceramics with (Eu3+,Yb3+):YNbO4 nanocrystals synthesized by secondary heat-treatments of glass of the Li2O–Al2O3–SiO2 system, for the first time, to the best of our knowledge. Heat treatments result in volume crystallization of RENbO4 with the sizes of 4–15nm. Crystals of rare-earth niobates with disordered fluorite structure (T′) appear during heat-treatment at 720–740°C for 6h, crystals with tetragonal structure (T) appear at higher temperatures or longer durations of heat-treatment, and in samples heat-treated at 1000°C, the monoclinic form (M) is detected additionally. Rare-earth niobates act as nucleating agents for bulk crystallization of β-quartz solid solutions, the main crystalline phase of the glass–ceramics, which ensures their good thermo-mechanical properties. Optical spectroscopy confirms entering of both Eu3+ and Yb3+ ions into the RENbO4 nanophase and their specroscopic properties variation according to the T′→T→M phase transformations. Under UV excitation, glass–ceramics heat-treated at 900°C provide intense red emission with the color coordinates x=0.665, y=0.335 (CIE 1931). In the sample, heat-treated at 1000°C, a partial reduction of Eu3+ to Eu2+ is observed which allows for tuning the color properties of emission. When excited in the near-IR by an InGaAs diode, the initial glass and glass–ceramics show red cooperative upconversion due to the 2Yb3+→Eu3+ energy transfer. The efficiency of the latter is ~10%. The developed materials due to the good emission and thermo-mechanical properties are promising for the development of color-tunable red phosphors.

Photodiode-based cutting interruption sensor for near-infrared lasers.

We report on a photodiode-based sensor system to detect cutting interruptions during laser cutting with a fiber laser. An InGaAs diode records the thermal radiation from the process zone with a ring mirror and optical filter arrangement mounted between a collimation unit and a cutting head. The photodiode current is digitalized with a sample rate of 20 kHz and filtered with a Chebyshev Type I filter. From the measured signal during the piercing, a threshold value is calculated. When the diode signal exceeds this threshold during cutting, a cutting interruption is indicated. This method is applied to sensor signals from cutting mild steel, stainless steel, and aluminum, as well as different material thicknesses and also laser flame cutting, showing the possibility to detect cutting interruptions in a broad variety of applications. In a series of 83 incomplete cuts, every cutting interruption is successfully detected (alpha error of 0%), while no cutting interruption is reported in 266 complete cuts (beta error of 0%). With this remarkable high detection rate and low error rate, the possibility to work with different materials and thicknesses in combination with the easy mounting of the sensor unit also to existing cutting machines highlight the enormous potential for this sensor system in industrial applications.

Optical Cutting Interruption Sensor for Fiber Lasers

We report on an optical sensor system attached to a 4 kW fiber laser cutting machine to detect cutting interruptions. The sensor records the thermal radiation from the process zone with a modified ring mirror and optical filter arrangement, which is placed between the cutting head and the collimator. The process radiation is sensed by a Si and InGaAs diode combination with the detected signals being digitalized with 20 kHz. To demonstrate the function of the sensor, signals arising during fusion cutting of 1 mm stainless steel and mild steel with and without cutting interruptions are evaluated and typical signatures derived. In the recorded signals the piercing process, the laser switch on and switch off point and waiting period are clearly resolved. To identify the cutting interruption, the signals of both Si and InGaAs diodes are high pass filtered and the signal fluctuation ranges being subsequently calculated. Introducing a correction factor, we identify that only in case of a cutting interruption the fluctuation range of the Si diode exceeds the InGaAs diode. This characteristic signature was successfully used to detect 80 cutting interruptions of 83 incomplete cuts (alpha error 3.6%) and system recorded no cutting interruption from 110 faultless cuts (beta error of 0). This particularly high detection rate in combination with the easy integration of the sensor, highlight its potential for cutting interruption detection in industrial applications.

In Vitro Effect of 808-nm Diode Laser on Proliferation and Glycosaminoglycan Synthesis of Rabbit Articular Chondrocytes

The aim of the study was to assess the in vitro effect of 808-nm InGaAs diode laser on rabbit articular chondrocyte proliferation and sulphated glycosaminoglycan (sGAG) synthesis in alginate bead. Previous studies revealed either positive or negative stimulatory effects of laser on different types of cells. A 808-nm InGaAs diode laser at 1.0W power output was used to irradiate the rabbit chondrocytes in alginate beads with energy densities of 31 J/㎠ (G 1) and 62 J/㎠ (G 2) corresponding to the experimental groups for 10 seconds and 20 seconds, respectively at 24, 48, 72 and 96 hours after seeding. Control group was left untreated. MTT assay was performed at 1 week and 2 weeks after the 1 st laser irradiation in alginate beads. sGAG synthesis in alginate beads at 1 week and 2 weeks were determined by DMMB assay. Histological evaluation for cellular distribution and sGAG deposition around the cells were performed by alcian blue stain. MTT assay revealed no positive stimulatory effect in cell proliferation in alginate bead. DMMB assay results showed significantly increased sGAG production in G 2 chondrocytes at 2 weeks. Image analysis of alcian blue stained slides also showed significantly higher percentage of positive alcian blue stain in G 2 chondrocytes. This result suggests that 808-nm InGaAs diode laser with 1.0 W power output although cannot stimulate cell proliferation it can increase the cell secretion activity and sGAG deposition in alginate beads.

Reproducible quantification of ethanol in gasoline via a customized mobile near-infrared spectrometer

This work describes the modification of an InGaAs diode array detector equipped miniaturized near-infrared (NIR) spectrometer enabling the reliable quantification of ethanol blended gasoline. A transflectance measurement cell is presented, utilizing a thermoelectric cooling (TEC) appliance ensuring thermostatic measurement conditions and a gold-coated spherical mirror as a reflector superior to conventional Spectralon®. In total, four measurement modes (Spectralon® reflector, gold reflector and either reflectors with employed TEC) are discussed, enabling a straightforward comparison of the results. The test-set validated multivariate partial least squares regression (PLSR) model of the measurement mode involving both gold mirror and TEC yielded an Rval2 value of 0.997, a limit of detection (LOD) of 0.68% w/w, a limit of quantification (LOQ) of 2.04% w/w, a standard error of prediction (SEP) of 0.21% w/w and a ratio performance deviation (RPD) of 15.2 while utilizing a single latent variable (LV). The NIR band assignment in this work has been established by employing the vibrational self-consistent field second order perturbative treatment (PT2-VSCF) and the computationally derived absorption maxima are compared to the experimentally observed data.

An InGaAlAs–InGaAs Two-Color Photodetector for Ratio Thermometry

We report the evaluation of a molecular-beam epitaxy grown two-color photodetector for radiation thermometry. This two-color photodetector consists of two p+in+ diodes, an In0.53Ga0.25Al0.22As (hereafter InGaAlAs) p+in+ diode, which has a cutoff wavelength of 1180 nm, and an In0.53Ga0.47As (hereafter InGaAs) p+in+ diode with a cutoff wavelength of 1700 nm. Our simple monolithic integrated two-color photodetector achieved comparable output signal and signal-to-noise (SNR) ratio to that of a commercial two-color Si-InGaAs photodetector. The InGaAlAs and InGaAs diodes detect blackbody temperature as low as 275°C and 125°C, respectively, with an SNR above 10. The temperature errors extracted from our data are 4°C at 275°C for the InGaAlAs diode and 2.3°C at 125°C for the InGaAs diode. As a ratio thermometer, our two-color photodetector achieves a temperature error of 12.8°C at 275°C, but this improves with temperature to 0.1°C at 450°C. These results demonstrated the potential of InGaAlAs-InGaAs two-color photodetector for the development of high performance two-color array detectors for radiation thermometry and thermal imaging of hot objects.

Planar InGaAs p-i-n Photodiodes With Transparent-Conducting-Based Antireflection and Double-Path Reflector

In this letter, we report on the design of large-area planar InP/InGaAs/InP heterostructure p-i-n photodiodes (PIN-PDs) with gallium-doped zinc oxide (GZO)/SiOx antireflective bilayer and AuGe/Au double-path reflectors for the enhancement in the position sensitivity and device response. The heavily GZO layer was grown on top of the InGaAs PIN-PDs by plasma-mode atomic layer deposition to improve the lateral resistance effect. The GZO/SiOx antireflection (AR) exhibits an average optical reflectance of below 5% in the infrared (IR) spectrum. Then, the combination of two features of AR coating and double-path reflector is employed to decrease incident light loss and increase double-path absorption. The dark current is less than several nanoamperes and the breakdown voltage is higher than 40 V reverse bias for the large-area InGaAs diode with 750- μm-diameter region. The device responsivity is 1.0 and 1.2 A/W at 1310-and 1550-nm wavelengths, respectively. Under the light illumination of 1550-nm wavelength, the photosensitivity shows good uniformity in the light-received area. The quantum efficiency is higher than 90% in the whole IR region, and the cutoff wavelength is 1650 nm.

Concentration Dependent Studies on the Laser-Induced Mid-Infrared Emission from KCl-NaCl Tablets

Laser Induced Breakdown Spectroscopy (LIBS) is a technique for determining the elemental composition of a chemical substance. Pumping with a 1064nm Nd:YAG pulse laser, mid-infrared emissions from LIBS plasma produced from KCl were examined between 2.0&micro;m and 4.5&micro;m, with atomic emission lines observed at 2.72&micro;m, 3.15&micro;m, 3.77&micro;m and 4.05&micro;m for potassium, consistent with NIST atomic spectra database. With further focus on the 2.72&micro;m emission, detection limit studies were carried on different concentration samples of KCl_NaCl mix, to determine the detection limit of potassium (K). A limit of detection of ~0.19wt%/wt was obtained for potassium in the mid-IR region. Full Text: PDF References D.A. Cremers, L.J. Radziemski, "123456", Handbook of Laser-Induced Breakdown Spectroscopy (John Wiley, 2006) [CrossRef] C. Pasquini, J. Cortez, L.M. C. Silva, F.B. Gonzaga, "Laser Induced Breakdown Spectroscopy", J. Braz. Chem. Soc. 18, 463 (2007) [CrossRef] L.J. Radziemski, D.A. Cremers, M. Bostian, R.C. Chinni, C. Navarro-Northrup, "Laser-Induced Breakdown Spectra in the Infrared Region from 750 to 2000 nm Using a Cooled InGaAs Diode Array Detector", App. Spectroscopy 61, 1141 (2007) [CrossRef] C.S.-C. Yang, E.E. Brown, U.H. Hommerich, S.B. Trivedi, A.C. Samuels, A.P. Snyder, "Mid-Infrared Emission from Laser-Induced Breakdown Spectroscopy", App. Spectroscopy 61, 321 (2007) [CrossRef] C.S.-C. Yang, E.E. Brown, U.H. Hommerich, S.B. Trivedi, A.C. Samuels, A.P. Snyder, "Mid-Infrared Laser-Induced Breakdown Spectroscopy Emissions from Alkali Metal Halides", App. Spectroscopy 62, 714 (2008) [CrossRef] W. Tawfik Y. Mohamed, "Improved LIBS limit of detection of Be, Mg, Si, Mn, Fe and Cu in aluminum alloy samples using a portable Echelle spectrometer with ICCD camera", Optics and Laser Techn. 40, 30 (2008) [CrossRef] Potassium Gluconate?Dietary supplement produced by Pharmavite? LLC, purchased as a non-prescription drug at Walgreens. M.A. Ismail, H. Imam, A. Elhassan, W.T. Youniss, M.A. Harith, "LIBS limit of detection and plasma parameters of some elements in two different metallic matrices", J. Anal. At. Spectrom. 19, 489 (2004) [CrossRef]

Femtosecond diode laser MOPA system at 920 nm based on asymmetric colliding pulse mode-locking

We report on the generation of 267 fs long pulses with a peak power of 661 W emitted by an InGaAs diode laser master-oscillator power-amplifier (MOPA) system with an external grating compressor. The oscillator emits strongly chirped picosecond pulses with several nanometer of bandwidth, which can be amplified without significant phase modulation and are compressed to femtosecond pulses after leaving the amplifier. We used a diode laser module for asymmetric colliding pulse mode-locking and optimized the collision point and the relative intensity of the counter-propagation pulses.

周期极化掺镁铌酸锂光学参量振荡器时域特性的实验研究

An optical parametric oscillator based on periodically poled MgO doped lithium niobate(PPMgLN-OPO) is reported.The output temporal characteristics of PPMgLN-OPO are discussed by varying its domain period and temperature tuning as well as pump power.In this experiment,the pulse width of pumping light and signal light is measured respectively by adopting MOTORULA's Si-diode and JUDSON's InGaAs diode as detectors.LD end-pumped Q-switched Nd∶YVO4 laser operating at a repetition rate of 19 kHz is used as pump source,when the pump power is 1 008 mW,PPMgLN-OPO produces the signal output power of 238 mW with the smallest pulse width of 9.3 ns,its optical-optical conversion efficiency is 23.6%,and the pulse width of signal wave is narrowed significantly.

Intracavity frequency doubling of an InGaAs diode laser passivelyQ-switched with GaAs saturable absorber

A mathematical model describing the dynamic emission of the intracavity frequency doubling (IFD) of a Q-switched InGaAs/KTP diode laser with a GaAs saturable absorber has been developed. The suggested model describes the temporal behavior of the diode laser system, GaAs saturable absorber and the KTP crystal. This model allows studying the impact of the variations of the input pumping diode laser parameters on the characteristics of the IFD of a passive Q-switched InGaAs/KTP output pulse. The simulation shows that the effect of the two-photon absorption plays an important role in the formation of the output laser pulse. Moreover, the nonlinear losses in the GaAs wafer can limit the obtainable pulse power. The numerical calculations show that the Q-switching process eliminates the tail of the original diode laser pulse and gives single peak picosecond output pulses. A method for deduction of the rate equation parameters is presented. The rate equations can be resolved analytically using small-signal measurements. Moreover, a reduction of the unknown parameters has been described based on the treatment of the threshold of the steady-state and small-signal response methodology.

Laser-Induced Breakdown Spectra in the Infrared Region from 750 to 2000 nm Using a Cooled InGaAs Diode Array Detector

Emissions from a laser-induced breakdown spectroscopy (LIBS) plasma were examined in the region from 750 nm to 2000 nm. A Nd:YAG laser at 532 nm and 75 mJ per pulse were used to initiate the plasma. The detector was an InGaAs 1024 element diode array cooled to -100 degrees C. An f/4 spectrometer with gratings blazed for this region was used as the dispersive element. Survey spectra of soils, uranium, and other selected samples were taken in air and in a flow cell purged with argon at a local pressure of 0.84 x 10(5) Pa. Strong infrared lines of neutral aluminum, carbon, potassium, silicon, sulfur, and uranium, as well as once ionized lines of calcium, were observed out to 1670 nm. For potassium, the detection limits of the infrared (IR) system were compared with those obtained from a standard intensified charge-coupled device (ICCD) spectrometer arrangement, using the 766-770 nm doublet. Detection limits with the IR system were twice as high as those obtained from the ICCD detector.

Stable dual-wavelength operation of InGaAs diode lasers with volume Bragg gratings

Stable dual-wavelength operation of InGaAs diode lasers coupled with volume Bragg gratings has been demonstrated for the continuous wave and gain-switching regimes. Spectral narrowing down to 0.33nm has been realized with maximum output power of up to 1.85W from a broad area stripe laser diode in a single-grating external cavity configuration. Spectral separation from 0.5 (0.16THz)to6.5nm (2.05THz) has been obtained and an output power of up to 1.75W was achieved in dual-wavelength operation.

Growth, thermal and optical properties of Yb:GdYAl3(BO3)4 crystal

Single crystal of Yb:GdYAl3(BO3)4(Yb:GdYAB) has been grown by the flux method. The structure of Yb:GdYAB crystal has been determined by X-ray diffraction analysis. The experiment show that the crystal has the same structure as that of YAl3(BO3)4 crystal and its unit cell constants have been measured to be a=9.30146Å, c=7.24164Å, Vol=542.59Å3. The absorption and fluorescence spectrum of Yb:GdYAl3(BO3)4 crystal have also been measured at room temperature. In the absorption spectra, there are two absorption bands at 938nm and 974nm, respectively, which is suitable for InGaAs diode laser pumping. In the fluorescence spectra, there are two fluorescence peaks at 992 and 1040nm. The thermal properties of Yb:GdYAl3(BO3)4 crystal have been studied for the first time. The thermal expansion coefficient along c-axis is almost 5.4 times larger than that along a-axis. The specific heat of the crystal has been measured to be 0.77J/g°C at room temperature. The calculated thermal conductivity is 5.26Wm−1K−1 along a-direction.

Growth and spectral properties of Yb:FAP single crystal

In this paper, single crystal of ytterbium (Yb) doped Ca5(PO4)3F (FAP) has been grown along the c-axis by using the Czochralski method. The segregation coefficients of Yb3+ in the Yb:FAP crystal has been determined by ICP-AES method. The absorption spectrum, fluorescence spectrum and fluorescence lifetime of the Yb:FAP crystal has been also measured at room temperature. In the absorption spectra, there are two absorption bands at 904 and 982 nm, respectively, which are suitable for InGaAs diode laser pumping. The absorption cross-section (σabs) is 5.117 × 10−20 cm2 with an FWHM of 4 nm at 982 nm. The emission cross-section (σem) is 3.678 × 10−20 cm2 at 1042 nm. Favorable values of the absorption cross-section at about 982 nm are promising candidates for laser diode (LD) pumping.