IR Light Source Research Articles

Broadband tunable infrared emission of Ni2+-doped ZnGa/AlO4 integrated transparent glass ceramics

ZnGa/AlO4 provides an octahedral coordination field in which Ni2+ serves as the luminescent center and combines with highly attractive transparent glass ceramics, playing a crucial role in achieving broadband near-infrared (NIR) emission. Transparent glass-ceramics embedded with ZnGa/AlO4:Ni2+ mixed crystals prepared by secondary high-temperature melting methods retain the structural characteristics of the dual-phase crystal, which was confirmed by a series of structural and morphological characterization. Through fine tailoring, the surrounding Ni2+ ligand field environment was transformed, realizing special composite NIR emission characteristics with a half-maximum width (FWHM) exceeding 280 nm, which achieved the best results for now in kinds of similar materials. The results show that the NIR emission of ZnGa/AlO4:Ni2+-doped transparent glass-ceramics is significantly broadened while maintaining a high level and a long lifetime, which makes it an excellent candidate material for IR light sources and broadband fiber amplifiers.

Core–Clad High-Purity Rare-Earth-Doped Chalcogenide Glass Fibers as IR Light Sources

Core–Clad High-Purity Rare-Earth-Doped Chalcogenide Glass Fibers as IR Light Sources

Characterization of infrared free electron laser output profile through sum frequency generation spectroscopy

Infrared free electron laser is a unique broadband tuning IR light source and useful tool to trace the reaction and vibrational energy transfer dynamics. It is essential for the infrared free electron laser debug and optimization to accurately characterize the wavelength and micropulse profile of the infrared free electron laser output. By synchronizing the infrared free electron laser and tabletop femtosecond laser with high precision, infrared free electron laser-sum frequency generation setup, a sum frequency generation spectroscopy setup using infrared free electron laser pulses, is developed. Through sum frequency generation cross-correlation, the infrared free electron laser output wavelength and micropulse duration are measured from the delaytime-dependent infrared free electron laser-sum frequency generation spectra of a ZnS window. The infrared free electron laser-sum frequency generation measured infrared free electron laser wavelength is linearly correlated with the theoretically calculation with the fixed electron beam energy and variable undulator magnetic gaps. And the measured micropulse duration is 2.0 ps@5.25 µm and 2.9 ps@8.35 µm. These results demonstrate the excellent ability of sum frequency generation in the diagnostic and characterization of infrared free electron laser output profile, and the quality of the infrared free electron laser pulse structure.

Oxygen Defects in Single-Wall Carbon Nanotubes for Near-Infrared Light Emitters

A new peak with an increased intensity was observed in the photoluminescence (PL) spectra of single-walled carbon nanotubes (SWCNTs), exposed to UV irradiation in the presence of sodium hypochlorite. It was concluded on the basis of the spectroscopic data that the new PL peak is associated with oxygen defects in the SWCNT structure. The impact of environmental acidity on the optical properties of oxygen-doped SWCNTs (O-SWNTs) was investigated. An increased sensitivity of the new PL peak to the pH of the medium was observed. It was concluded that the usage of a pH-neutral medium is of crucial importance for the creation of IR light sources based on O-SWNTs. Keywords: single-walled carbon nanotubes, photoluminescence, localized exciton, acidity, infrared light emitters.

Кислородные дефекты в одностенных углеродных нанотрубках для источников излучения в ближнем инфракрасном диапазоне

A new peak with an increased intensity was observed in the photoluminescence (PL) spectra of single-walled carbon nanotubes (SWCNTs), exposed to UV irradiation in the presence of sodium hypochlorite. It was concluded on the basis of the spectroscopic data that the new PL peak is associated with oxygen defects in the SWCNT structure. The impact of environmental acidity on the optical properties of oxygen-doped SWCNTs (O-SWNTs) was investigated. An increased sensitivity of the new PL peak to the pH of the medium was observed. It was concluded that the usage of a pH-neutral medium is of crucial importance for the creation of IR light sources based on O-SWNTs.

Microemitter-Based IR Spectroscopy and Imaging with Multilayer Graphene Thermal Emission.

IR analyses such as Fourier transform infrared spectroscopy (FTIR) are widely used in many fields; however, the performance of FTIR is limited by the slow speed (∼10 Hz), large footprint (∼ millimeter), and glass bulb structure of IR light sources. Herein, we present IR spectroscopy and imaging based on multilayer-graphene microemitters, which have distinct features: a planar structure, bright intensity, a small footprint (sub-μm2), and high modulation speed of >50 kHz. We developed an IR analysis system based on the multilayer-graphene microemitter and performed IR absorption spectroscopy. We show two-dimensional IR chemical imaging that visualizes the distribution of the chemical information. In addition, we present high-spatial-resolution IR imaging with a spatial resolution of ∼1 μm, far higher than the diffraction limit. The graphene-based IR spectroscopy and imaging can open new routes for IR applications in chemistry, material science, medicine, biology, electronics, and physics.

Photomechanical actuation of polydimethylsiloxane/carbon black nanocomposite

Materials such as carbon black (CB), carbon nanotube, graphene, etc. have been found to deform on exposure to the light source. Introducing these materials into polymers could convert them to photo-responsive composites. This is demonstrated by the experiment in which polydimethylsiloxane (PDMS) polymer containing CB nanofiller composites is prepared, and its photomechanical actuation from exposure to IR light source is recorded using a laser displacement sensor. The particle size analysis reveals the size of the CB, which is verified by the dynamic light scattering method. The UV-vis-IR spectrophotometer study shows that an increase in the light absorbance capacity of nanocomposites compared to the plain polymer. The PDMS/CB nanocomposite beam exhibited a significant deformation compared to plain PDMS. Deformation of the order of 10-11 mm is observed for a given IR source. The deformation found to have good repeatability but with some thermal hysteresis in cyclic actuation and de-actuation.

Design of a six-gas NDIR gas sensor using an integrated optical gas chamber.

A non-dispersive infrared (NDIR) gas sensor with an integrated optical gas chamber was designed to accurately detect multiple gas concentrations in a complex polluted environment. This chamber consists of a hexagonal prism shell and a reflection plate. In particular, six dual-channel infrared detectors for sensing different gases and one collimated infrared light source are integrated in the gas chamber. The IR light emitted by the collimated IR light source arrives at these detectors after four reflections. The result of simulation and data collection for optical path length and luminous flux shows that the average optical path length in the chamber is 63 mm, and the effective utilization rate of the luminous flux can reach 78.8%. The highly compact NDIR sensor can detect the concentrations of a mixture of gases (CO, CO2, CH4, H2CO, NH3, and NO with a volume fraction ranging from 0 to 4%).

Structure of Proton-Bound Methionine and Tryptophan Dimers in the Gas Phase Investigated with IRMPD Spectroscopy and Quantum Chemical Calculations.

The structures of three proton-bound dimers (Met2H+, MetTrpH+, and Trp2H+) are investigated in the gas phase with infrared multiple photon disassociation (IRMPD) spectroscopy in combination with quantum chemical calculations. Their IRMPD spectra in the range of 600–1850 cm–1 are obtained experimentally using an FT-ICR mass spectrometer and the CLIO free electron laser as an IR light source. The most abundant conformers are elucidated by comparing the IRMPD spectra with harmonic frequencies obtained at the B3LYP-GD3BJ/6-311++G** level of theory. Discrepancies between the experimental and theoretical data in the region of 1500–1700 cm–1 are attributed to the anharmonicity of the amino bending modes. We confirm the result of a previous IRMPD study that the structure of gas-phase Trp2H+ is charge-solvated but find that there are more stable structures than originally reported (Feng, R.; Yin, H.; Kong, X. Rapid Commun. Mass Spectrom.2016, 30, 24–28). In addition, gas-phase Met2H+ and MetTrpH+ have been revealed to have charge-solvated structures. For all three dimers, the most stable conformer is found to be of type A. The spectrum of Met2H+, however, cannot be explained without some abundance of type B charge-solvated conformers as well as salt-bridged structures.

Surface-Enhanced Thermal Emission Spectroscopy with Perfect Absorber Metasurfaces

Surface-enhanced spectroscopy techniques using plasmonic nanoantennas or metasurfaces help to reduce the detection limit for biochemical sensing. While infrared spectroscopy is an excellent tool to identify a molecular species, a typically expensive IR light source is needed. We report a surface enhanced spectroscopy technique based on the thermal emission of III–V semiconductor metasurfaces. The presence of a molecular species grafted on the surface modulates the emission spectrum analogously to the modulation achieved in surface-enhanced infrared absorption (SEIRA) spectroscopy. The vibrational fingerprint of the molecular species is detected due to the electromagnetic field enhancement obtained with a plasmonic metasurface. Because the metasurface acts simultaneously as radiation source and sensor chip, the experimental setup is simplified and therefore more compact and potentially more cost-efficient. This novel approach of surface-enhanced thermal emission spectroscopy (SETES) is appealing for miniat...

Focus on photonics, spectrometry, and spectroscopy

Focus on photonics, spectrometry, and spectroscopy

Infrared microscopy in the study of cellular biochemistry

This is a personal overview of the background, motivation and objectives in the application of infrared spectromicroscopy techniques to the study of cellular biochemistry, as detailed in a presentation given at WIRMS2017. It was not the aim of the presentation, nor is it the aim of the present article, to be a systematic review of the field of biological IR microscopy. Rather, it highlights the motivation for the author to use IR microscopy in biological research, with an emphasis on experiments that address specific questions in biochemical and cellular research. It also comments on the role of conventional light sources and synchrotron radiation in these experiments and justifies the use of synchrotron light in their implementation. The synchrotron advantage for experiments on live cells is reassessed in view of recent developments in the technology of IR light sources, in particular the introduction of novel designs of mid-infrared lasers. Finally, future applications of synchrotron IR light to the field are discussed with respect to the introduction of near-field techniques for IR imaging and spectroscopy of cellular samples, such as sSNOM and AFM-IR.

Dispersion properties of a single-mode windmill single crystal Sapphire optical fiber and its broadband infrared supercontinuum generation

The effective refractive indices of each mode of a windmill single crystal sapphire fiber as function of wavelength can be obtained by finite element method. Recently, it is shown that this fiber operates in single-mode condition for a wide wavelength range. The dispersion and the slope of dispersion for the fundamental mode of a windmill single crystal sapphire fiber are properly obtained making use of the measured values of the refractive index as a function of the wavelength. Subsequently, the pulse evolution along this windmill fiber is investigated for low peak power pulses. Due to high applicability of broadband light sources, here, supercontinuum generation process is also studied when high peak power pulses are launched into the single-mode windmill single crystal sapphire fiber. Due to its unique optical properties, the single-mode windmill single crystal sapphire fiber can be used to generate broadband IR supercontinuum light compared with the conventional single crystal sapphire fiber. Our simulation results indicate that generated output spectrum contains dense frequency combs in a wide range. This broadband IR light source facilitates IR spectroscopy while its frequency combs are important in the development and improvement of the optical metrology.

Intensity modulated silver coated glass optical fiber refractive index sensor

Miniature optical fiber sensors with thin films as sensitive elements could open new fields for optical fiber sensor applications. Thin films work as sensitive elements and a transducer to get response and feedback from environments, in which optical fibers act as a signal carrier. A novel Ag coated intensity modulated optical fiber sensor based on refractive index changes using IR and UV-Vis (UV-visible) light sources is proposed. The sensor with an IR light source has higher sensitivity compared to a UV-Vis source. When the refractive index is enhanced to 1.38, the normalized intensity of IR and UV-Vis light diminishes to 0.2 and 0.8, respectively.

Ultralarge All‐Inorganic Perovskite Bulk Single Crystal for High‐Performance Visible–Infrared Dual‐Modal Photodetectors

Visible‐infrared dual‐modal light harvesting is crucial for various optoelectronic devices, particularly for solar cells and photodetectors. For the first time, this study reports on large 25 cm3‐volume all‐inorganic perovskite CsPbBr3 single crystal (SC) with an emphasis on the observed visible‐infrared dual‐modal light harvesting and sensing as demonstrated by the high‐performance visible‐infrared dual‐modal photodetectors. First, ultralarge 25 cm3‐volume CsPbBr3 SC ingots with trapping state density as low as of 1 × 109 cm−3 have been achieved by a modified Bridgman growth method. The volume reported here is the largest CsPbX3 (X = Cl, Br, I) all‐inorganic perovskite system up to now, and the SC can be facilely cut into SC wafers with a diameter of 25 mm for various optoelectronic devices. Furthermore, these CsPbBr3 SCs exhibit a visible absorbance coefficient, a near‐infrared (IR) two‐phonon absorption coefficient, a carrier diffusion length, and a mobility as high as of 105 cm−1, 3.7 cm per Goeppert‐Mayer (GM), 10 µm and 2000 cm2 V−1 s−1, respectively. These merits match well to the requirements of high‐performance Vis‐IR dual‐modal light harvesting optoelectronic devices, which has been demonstrated by the CsPbBr3 SC photodetectors operated under the irradiation of both visible and IR light sources with light on/off ratio higher than 103. These results demonstrate the CsPbBr3 SCs with high visible‐infrared dual‐modal light harvesting capability and excellent electrical transporting properties have a huge potential in various optoelectronic devices, such as solar cells, photodetectors, and lasers.

Bonding and electronic states of boron in silicon nanowires characterized by an infrared synchrotron radiation beam.

The infrared synchrotron radiation (IR-SR) beamline of SPring-8 as an IR light source was applied to characterize boron (B) atoms in silicon nanowires (SiNWs). The use of an IR-SR beam with much higher brilliance than conventional IR light sources and a wide range of wavenumbers from visible to far IR regions made it possible to detect a local vibrational mode of B in SiNWs. The use of this technique has also made it possible to detect other IR peaks related to transitions of a bound hole from the ground state of a B acceptor atom to excited states, clarifying the electronic state of B acceptors in SiNWs.

The Observations of the IR Sensitivity Enhancement, Negative Differential Resistance and Hysteresis in a Microelectronic Gas Discharge Device with GaP

In this paper, some interesting features of a microelectronic gas discharge device with GaP semiconductor are reported. The device is a complicated plasma system with a metal anode and a GaP cathode. A discharge occurs in the micro-scaled gap, when a voltage larger than the breakdown value is applied between these electrodes. Since large region of applied voltages are scanned in the microelectronic gas discharge device, both Townsend and glow regimes are clearly observed and a complete electrical and optical responses of the device has been clarified. Following the increase of U gradually, different light emission intensities occur as a result of discharge current I. An IR light source is also used in order to test the IR excitation of the microstructure. Although it has been believed that the GaP is sensitive to UV and visible regions, it has been proven for the first time that the IR sensitivity of GaP can be enhanced by using microelectronic gas discharge device, when an appropriate parameter set is applied. Moreover, a negative differential resistance regime, which is important for the high frequency microwave applications, has been observed at moderate voltages. In addition to the negative differential resistance regime, certain hysteresis behaviour is also observed in the sweep up/down cases of U. DOI: http://dx.doi.org/10.5755/j01.eee.20.1.6173

Research of Weak Signal Processing Circuit Based on Non-Dispersive Infrared Automobile Exhaust Sensor

Based on the analysis of infrared detection technology and Lambert-Beer law a new kind of quad-channel non-dispersive infrared (NDIR) gas concentration analyzer is designed by applying the modulated IR light source and a quad thermopile sensor into automobile exhaust gases concentration detection. The emphasis is paid on the analysis of modulated light source, gas chamber, sensor and the acquisition and processing circuit of the signal. The result of simulation and analysis of the designed circuit proved the feasibility of the design.

Infrared Multiple Photon Dissociation Spectroscopy and Computational Studies of O-Glycosylated Peptides

The infrared multiple photon dissociation (IRMPD) spectra of O-glycosylated peptides in the gas phase were studied in the IR scanning range of 5.7-9.5 μm. Fragmentation of protonated and sodiated O-glycopeptides was investigated using electrospray ionization (ESI) Fourier-transform ion cyclotron resonance (FTICR) mass spectrometry (MS) with a free electron laser (FEL). FEL is used in the IRMPD technique as a tunable IR light source. In the IRMPD spectroscopic analysis of the protonated O-glycopeptide, fragment ions of the b/y and B/Y types were observed in the range of 5.7-9.5 μm, corresponding to the cleavage of the backbone in the parent amino acid sequence and glycosyl bonds, whereas the spectra of the sodiated glycopeptide showed major peaks of photoproducts of the B/Y type in the range of 8.4-9.5 μm. The IRMPD spectra of the O-glycopeptides were compared with simulated IR spectra for the structures obtained from the molecular dynamics.

A free geometry model-independent neural eye-gaze tracking system

BackgroundEye Gaze Tracking Systems (EGTSs) estimate the Point Of Gaze (POG) of a user. In diagnostic applications EGTSs are used to study oculomotor characteristics and abnormalities, whereas in interactive applications EGTSs are proposed as input devices for human computer interfaces (HCI), e.g. to move a cursor on the screen when mouse control is not possible, such as in the case of assistive devices for people suffering from locked-in syndrome. If the user’s head remains still and the cornea rotates around its fixed centre, the pupil follows the eye in the images captured from one or more cameras, whereas the outer corneal reflection generated by an IR light source, i.e. glint, can be assumed as a fixed reference point. According to the so-called pupil centre corneal reflection method (PCCR), the POG can be thus estimated from the pupil-glint vector.MethodsA new model-independent EGTS based on the PCCR is proposed. The mapping function based on artificial neural networks allows to avoid any specific model assumption and approximation either for the user’s eye physiology or for the system initial setup admitting a free geometry positioning for the user and the system components. The robustness of the proposed EGTS is proven by assessing its accuracy when tested on real data coming from: i) different healthy users; ii) different geometric settings of the camera and the light sources; iii) different protocols based on the observation of points on a calibration grid and halfway points of a test grid.ResultsThe achieved accuracy is approximately 0.49°, 0.41°, and 0.62° for respectively the horizontal, vertical and radial error of the POG.ConclusionsThe results prove the validity of the proposed approach as the proposed system performs better than EGTSs designed for HCI which, even if equipped with superior hardware, show accuracy values in the range 0.6°-1°.