This PDF file contains the front matter associated with SPIE Proceedings Volume 9755, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and Conference Committee listing.

The US Army’s future operating concept will rely heavily on sensors, nano-electronics and photonics technologies to rapidly develop situational understanding in challenging and complex environments. Recent technology breakthroughs in integrated 3D multiscale semiconductor modeling (from atoms-to-sensors), combined with ARL’s Open Campus business model for collaborative research provide a unique opportunity to accelerate the adoption of new technology for reduced size, weight, power, and cost of Army equipment. This paper presents recent research efforts on multi-scale modeling at the US Army Research Laboratory (ARL) and proposes the establishment of a modeling consortium or center for semiconductor materials modeling. ARL’s proposed Center for Semiconductor Materials Modeling brings together government, academia, and industry in a collaborative fashion to continuously push semiconductor research forward for the mutual benefit of all Army partners.

We present spectroscopic measurements performed with an EC-QCL combining a broadly tunable quantum cascade laser chip with a tuning range of more than 300 cm^-1 and a resonantly driven MOEMS scanner with an integrated diffraction grating for wavelength selection in Littrow configuration. The grating geometry was optimized to provide high diffraction efficiency over the wide tuning range of the QCL, thus assuring high power density and high spectral resolution in the MIR range. The MOEMS scanner has a resonance frequency of 1 kHz, hence allowing for two full wavelength scans, one up and the other downwards, within 1 ms. The capability for real-time spectroscopic sensing based on MOEMS EC-QCLs is demonstrated by transmission measurements performed on polystyrene reference absorber sheets as well as on gaseous samples of carbon monoxide. For the latter one, a large portion of the characteristic CO absorption band containing several absorption lines in the range of 2070 cm^-1 to 2280 cm^-1 can be monitored in real-time.

A sensor system based on a CW EC-QCL (mode-hop-free range 1225-1285 cm^-1) coupled with long-path absorption spectroscopy was developed for the monitoring of gas-phase hydrogen peroxide (H₂O₂) using an interference-free absorption line located at 1234.055 cm^-1. Wavelength modulation spectroscopy (WMS) with second harmonic detection was implemented for data processing. Optimum levels of pressure and modulation amplitude of the sensor system led to a minimum detection limit (MDL) of 25 ppb using an integration time of 280 sec. The selected absorption line for H₂O₂, which exhibits no interference from H₂O, makes this sensor system suitable for sensitive and selective monitoring of H₂O₂ levels in decontamination and sterilization processes based on Vapor Phase Hydrogen Peroxide (VPHP) units, in which a mixture of H₂O and H₂O₂ is generated. Furthermore, continuous realtime monitoring of H₂O₂ concentrations in industrial facilities employing this species can be achieved with this sensing system in order to evaluate average permissible exposure levels (PELs) and potential exceedances of guidelines established by the US Occupational Safety and Health Administration for H₂O₂.

A rapidly-swept external-cavity quantum cascade laser with an open-path Herriott cell is used to quantify gas-phase chemical mixtures of D₂O and HDO at an update rate of 40 Hz (25 ms measurement time). The chemical mixtures were generated by evaporating D₂O liquid near the open-path Herriott cell, allowing the H/D exchange reaction with ambient H₂O to produce HDO. Fluctuations in the ratio of D₂O and HDO on timescales of < 1 s due to the combined effects of plume transport and the H/D exchange chemical reaction are observed. Based on a noise equivalent concentration analysis of the current system, detection limits of 147.0 ppbv and 151.6 ppbv in a 25 ms measurement time are estimated for D₂O and HDO respectively with a 127 m optical path. These detection limits are reduced to 23.0 and 24.0 ppbv with a 1 s averaging time for D₂O and HDO respectively. Detection limits < 200 ppbv are also estimated for N₂O, F134A, CH₄, Acetone, and SO₂ for a 25 ms measurement time.

We employ active hyperspectral imaging using tunable mid-infrared (MIR) quantum cascade lasers for contactless identification of solid and liquid contaminations on surfaces. By collecting the backscattered laser radiation with a camera, a hyperspectral data cube, containing the spatially resolved spectral information of the scene is obtained. Data is analyzed using appropriate algorithms to find the target substances even on substrates with a priori unknown spectra. Eye-save standoff detection of residues of explosives and precursors over extended distances is demonstrated and the main purpose of our system. However, it can be applied to any substance with characteristic reflectance / absorbance spectrum. As an example, we present first results of monitoring food quality by distinguishing fresh and mold contaminated peanuts by their MIR backscattering spectrum.

Mid-infrared laser sources (3-14 μm wavelengths) which have wide spectral coverage and high output power are attractive for many applications. This spectral range contains unique absorption fingerprints of most molecules, including toxins, explosives, and nerve agents. Infrared spectroscopy can also be used to detect important biomarkers, which can be used for medical diagnostics by means of breath analysis. The challenge is to produce a broadband midinfrared source which is small, lightweight, robust, and inexpensive. We are currently investigating monolithic solutions using quantum cascade lasers. A wide gain bandwidth is not sufficient to make an ideal spectroscopy source. Single mode output with rapid tuning is desirable. For dynamic wavelength selection, our group is developing multi-section laser geometries with wide electrical tuning (hundreds of cm^-1). These devices are roughly the same size as a traditional quantum cascade lasers, but tuning is accomplished without any external optical components. When combined with suitable amplifiers, these lasers are capable of multi-Watt single mode output powers. This manuscript will describe our current research efforts and the potential for high performance, broadband electrical tuning with the quantum cascade laser.

We report the first demonstration of a leak sensor based on a mid-IR quartz-enhanced photoacoustic (QEPAS) spectroscopic technique. A QEPAS sensor was integrated in a vacuum seal test station for mechatronic components. The laser source is a quantum cascade laser emitting at 10.56 μm, resonant with a strong absorption band of sulfur hexafluoride (SF₆), which was selected as target gas for leak detection. The minimum detectable concentration of the QEPAS sensor is 6.9 ppb with an integration time of 1 s. This detection sensitivity allowed to measure SF6 leak flows as low as 3x10^-5 standard cm³.

In addition to the phase uctuation induced by spontaneous emission, instantaneous carrier variations in semiconductor lasers generate coupling between optical gain and refractive index. This coupling between phase and amplitude of the electric field in the optical cavity is driven by the linewidth enhancement factor, which is responsible for the optical linewidth broadening, occurrence of nonlinearities or gain asymmetry, due to the curvature difierence between the conduction and valence bands. This key parameter typically takes values between 2 and 6 in interband lasers with quantum well or quantum dot active media. In quantum cascade lasers, since the lasing transition occurs between two subbands of the conduction band that have therefore similar curvatures, the linewidth enhancement factor was expected to be naught. However sub-threshold linewidth enhancement factor was measured taking values from -0.5 to 0.5 and the above-threshold linewidth enhancement factor at room temperature was found between 0.2 and 2.4. In this work, the linewidth enhancement factor of a mid-infrared quantum cascade laser emitting around 5.6 μm is measured using either the wavelength shift under optical feedback or self-mixing interferometry, resulting in values ranging from 0.8 to 3. Furthermore, a strong increase of the linewidth enhancement factor with the pump current was observed, that can be explained by a relatively large gain compression in such structures, of the order of 5 × 10^-15 cm³.

We report cw wallplug efficiencies (WPEs) for mid-infrared interband cascade lasers (ICLs) that are comparable to those of state-of-the-art quantum cascade lasers at temperatures ranging from the cryogenic regime to room temperature. The continuous wave (cw) WPE for 10-stage broad-area devices remains above 40% for temperatures up to 125 K, and is still <30% at T = 175 K. At 80 K the threshold current density for a 2-mm-long cavity is only 11 A/cm², and slope efficiencies are < 2.2 W/A at all temperatures ≤ 200 K. A 32-μm-wide × 3-mm-long ridge with 7 active stages and high-reflection and anti-reflection coatings on the two facets displays a cw WPE of 24% at T = 200 K and 12% at T = 300 K. The cw WPE of another narrow-ridge ICL was 18% at room temperature.

A tunable diode laser absorption spectroscopy (TDLAS)-based methane sensor, employing a miniature dense-pattern multi-pass gas cell (MPGC) and a continuous wave, room temperature interband cascade laser (ICL), is reported. The optical integration based on an advanced folded optical path design and an efficient ICL control system with appropriate electrical power management results in a methane sensor with a small footprint (32 × 20 × 17 cm³) and low-power consumption (6W). The direct absorption measurement strategy allows absolute quantitative assessments without any calibration. Polynomial and least-squares fit algorithms are employed to remove the baseline of the spectral scan and retrieve CH₄ concentrations, respectively. An Allan-Werle deviation analysis shows that the measurement precision can reach 1.4 ppb for a 60 s averaging time. Continuous measurements lasting seven days were performed to demonstrate the stability and robustness of the reported methane sensor.

In this work we present latest results on mid-infrared GaSb gain chips as high-output power narrow-linewidth continuouswave single-frequency laser sources for ultra-widely tunable spectroscopy and sensing applications. More than 30 mW CW output power with over 100 nm / chip tuning and < 1 MHz linewidth performance is demonstrated in the entire band from 1900 nm – 2450 nm covering most essential absorption features from CO, CO₂, NH₃, CH₄ and N₂O for environmental and medical applications. Finally, we report on complete single-frequency laser system with integrated gain-chip for highresolution spectroscopy and sensor applications.

Resonant plasmonic excitations in micro-scale structures at terahertz (THz) frequencies can make a large impact development of THz devises. A number of material systems have been proposed and demonstrated for THz plasmonic resonators, including doped semiconductors, materials with metallic behavior, such as graphene, graphite, and carbon nano-tubes, superconductors and topological insulators. However, experimental investigations of THz plasmonic resonators, which are typically a fraction of the free space wavelength in size, remain challenging. We demonstrate that THz near-field spectroscopy and imaging technique based on a subwavelength aperture probe can be employed to detect excitation of THz plasmons in carbon micro-fibers. Upon excitation of a single carbon fiber by a THz pulse, we observe a standing wave formed along the fiber length. The resonant frequency is consistent with the fundamental dipole mode, both in its value and in its dependence on the fiber length. The field of the standing wave is localized and it indicates the plasmonic nature of the excitation. The fact that the resonance frequency also depends on the material conductivity allows us to employ the THz near-field spectroscopy method to evaluate the material conductivity non-invasively. Furthermore we propose an alternative method for non-contact conductivity probing. It utilizes the relative amplitude of the surface plasmon field that can be measured by the near-field probe. The amplitude increases with the fiber conductivity and therefore it can be used for conductivity estimation.

We present three main material platforms: SOI, suspended Si and Ge on Si. We report low loss SOI waveguides (rib, strip, slot) with losses of ~1dB/cm. We also show efficient modulators and detectors realized in SOI, as well as filters and multiplexers. To extend transparency of SOI waveguides, bottom oxide cladding can be removed. We have fabricated low loss passive devices in a suspended platform that employ subwavelength gratings. Ge on Si material can have larger transparency range than suspended Si. We have designed passive devices in this platform, demonstrated all optical modulation and carried out two photon absorption measurements. We have also investigated theoretically free carrier optical modulation in Ge.

Tunable tensile-strained germanium (epsilon-Ge) thin films on GaAs and heterogeneously integrated on silicon (Si) have been demonstrated using graded III-V buffer architectures grown by molecular beam epitaxy (MBE). epsilon-Ge epilayers with tunable strain from 0% to 1.95% on GaAs and 0% to 1.11% on Si were realized utilizing MBE. The detailed structural, morphological, band alignment and optical properties of these highly tensile-strained Ge materials were characterized to establish a pathway for wavelength-tunable laser emission from 1.55 μm to 2.1 μm. High-resolution X-ray analysis confirmed pseudomorphic epsilon-Ge epitaxy in which the amount of strain varied linearly as a function of indium alloy composition in the InxGa1-xAs buffer. Cross-sectional transmission electron microscopic analysis demonstrated a sharp heterointerface between the epsilon-Ge and the InxGa1-xAs layer and confirmed the strain state of the epsilon-Ge epilayer. Lowtemperature micro-photoluminescence measurements confirmed both direct and indirect bandgap radiative recombination between the Γ and L valleys of Ge to the light-hole valence band, with L-lh bandgaps of 0.68 eV and 0.65 eV demonstrated for the 0.82% and 1.11% epsilon-Ge on Si, respectively. The highly epsilon-Ge exhibited a direct bandgap, and wavelength-tunable emission was observed for all samples on both GaAs and Si. Successful heterogeneous integration of tunable epsilon-Ge quantum wells on Si paves the way for the implementation of monolithic heterogeneous devices on Si.

In this work we investigated the effect of proton irradiation on the performance of long wavelength infrared (LWIR) InAs/GaSb photodiodes (λ_c = 10.2μm) based on the complementary barrier infrared detector (CBIRD) design. We found that irradiation with 68MeV protons up to the total ionizing dose TID = 200 kRad results in only small (about 15%) decrease of the Quantum Efficiency and does not increase the operational bias of the photodiodes. However, the irradiation causes a significant increase of the dark current from j_d = 5x10^-5 A/cm² at V_b = 0.1V and T = 80K to j_d = 6x10^-3 A/cm2 at TID = 200 kRad. This change in the dark current mechanism can be attributed to the onset of surface leakage current, generated by the trap assisted tunneling processes in the proton displacement damage areas near the device sidewalls.

Antimony-based Interband Cascade (IC) photodetectors are emerging as viable candidates for highperformance infrared applications, especially at high operating temperatures. In our previous IC detector designs using InAs/GaSb Type-II superlattices, the quantum efficiency was relatively low as the designs were optimized for high signal to noise ratio. Here we report our recent development of low-noise mid-IR IC photodetectors with high external quantum efficiency. By adopting IC detectors with thicker absorber designs, the quantum efficiency of these mid-IR IC detectors has been increased up to 35%. These IC devices continue to have low-dark current and high temperature operations. Some further analysis on the device characteristics is also presented.

We report on the performance of long wavelength infrared type-II InAs-based InAs/GaAsSb superlattice photodiodes grown by molecular-beam epitaxy. The detectors had a 100% cutoff wavelength of ~ 9.7 μm and a peak current responsivity of 2.16 A/W at 80 K. The dark current density at -50 mV bias was 6.4×10^-4 A/cm² and the resistance-area product at zero bias (R0A) was 36.9 Ωcm². The black body detectivity and peak detectivity were 7.5×10¹⁰ cm Hz^1/2/W and 1.97×10¹¹ cm Hz^1/2/W, respectively. The quantum efficiency at 7.6 μm was measured to be ~34%. Good agreement was achieved between the measured I-V curves and the simulated ones, and between the experimental and theoretically predicted differential resistance values. At temperatures exceeding 75 K diffusion currents dominate the device performance. In the temperature range between 65 and 75 K, the performance of the InAs-based SL photodiodes is limited by GR processes. Trap-assisted tunneling current provides a significant contribution at temperatures below 65 K, while coherent tunneling currents are not of importance.

We report theoretical and experimental analysis of spin-injected VECSELs. First, we fabricate and characterize an optically pumped (100)-oriented InGaAs/GaAsP multiple quantum well VECSEL. The structure is designed to allow the integration of a Metal-Tunnel-Junction ferromagnetic spin-injector for future electrical injection. We report here the control at room temperature of the VECSEL polarization using optical spin injection in the active medium. The switching between two highly circular polarization states had been demonstrated using an M-shaped extended cavity in multi-modes lasing. This first result witnesses an efficient spin-injection in the active medium of the laser. Then, we report birefringence measurements of the VECSEL in oscillating conditions. The proposed technique relies on the measurement in the microwave domain of the beatnote between the oscillating mode and the amplified spontaneous emission of the cross-polarized non-lasing field lying in the following longitudinal mode. This technique is shown to offer extremely high sensitivity and accuracy enabling to track the amount of residual birefringence according to the laser operation conditions. Finally, we discuss the compensation of the residual linear phase anisotropy by controlling the birefringence of an intracavity electro-optical crystal. A 44-fold birefringence reduction is obtained. Besides, we study the modification of the laser polarization eigen states with birefringence compensation: a rotation of the linear polarization state is observed when the total phase anisotropy is reduced. An elliptical polarization eigen state is obtained at the minimum of the birefringence into the laser cavity, more favorable for spin injection.

We report on the all-optical control of chaotic optical resonators based on silicon on insulator (SOI) platform. We show that simple non-chaotic cavities can be tuned to exhibit chaotic behavior via intense optical pump- ing, inducing a local change of refractive index. To this extent we have fabricated a number of devices and demonstrated experimentally and theoretically that chaos can be triggered on demand on an optical chip.

We summarize here, and detail with numerical examples, the Quasi-Normal Mode theory which has been developed in a recent series of papers dealing with classical and quantum plasmonics. We present the semi-analytical formalism capable of handling the coupling of electromagnetic sources, such as point dipoles or free-propagating fields, with various kinds of dissipative and dispersive resonators. Due to its analyticity, the approach is very intuitive, and very versatile and can be applied to canonical problems of quantum optics and sensing with nanoresonators.

We designed cylindrical AlGaAs-on-aluminium-oxide all-dielectric nanoantennas with magnetic dipole resonance at near-infrared wavelengths. Our choice of material system offers a few crucial advantages with respect to the silicon-oninsulator platform for operation around 1.55μm wavelength: absence of two-photon absorption, high χ⁽²⁾ nonlinearity, and the perspective of a monolithic integration with a laser. We analyzed volume second-harmonic generation associated to a magnetic dipole resonance in these nanoantennas, and we predict a conversion efficiency exceeding 10^-3 with 1GW/cm² of pump intensity.

In this article, we present an overview of some popularly adopted synthesis methods of two-dimensional (2D) materials. We demonstrate doping methods which provide insights into the substrate impacts on synthesis of materials and provide routes to manipulate 2D layered materials‟ intrinsic electronic and magnetic properties of monolayer MoS₂. We also describe methods of synthesizing different heterostructures and elucidate their new transport and electronic properties.

The development and characterization of nitride QW structures grown by atomic layer epitaxy (ALEp) for device applications are discussed. We have grown epitaxial thin films (4-10nm) covering the full range of binary and ternary III-N compositions by ALEp. In this work, ALEp-grown QW structures are presented. Optical characteristics are discussed. Characterization of layer interfaces and composition are critical to the development of this growth technique for quantum-based devices. Structures to study this by atom probe tomography have been created. By understanding the structure of crystalline ALEp films with nanometer-scale thickness, the unique properties of these materials can be advanced for quantum-scale applications.

SOFRADIR is the worldwide leader on the cooled IR detector market for high-performance space, military and security applications thanks to a well mastered Mercury Cadmium Telluride (MCT) technology, and recently thanks to the acquisition of III-V technology: InSb, InGaAs, and QWIP quantum detectors. Strong and continuous development efforts are deployed to deliver cutting edge products with improved performances in terms of spatial and thermal resolution, low excess noise and high operability. The actual trend in quantum IR detector development is the design of very small pixel, with high operating temperature. To maintain the detector performances and operability at high temperature, the number of pixels exhibiting extra noise like 1/f and RTS noise must be limited. This paper presents the recent developments achieved in Sofradir in terms of HOT MCT extrinsic p on n technology, blue MW band (cut-off wavelength of 4.2μm at 150K) and extended MW band (cut-off wavelength of 5.3μm at 130K). Comparison between optimized and non-optimized technology will be presented in terms of NETD temperature dependency, MTF, 1/f noise and the corresponding impact on RFPN (Residual Fixe Pattern Noise) and its stability up to 170K will be shown.

Stray light in focal plane array (FPA) deteriorates the accuracy of hyper spectral imaging. Multiple reflections between FPA window and peripheral region of a sensor chip are considered to be the major sources of stray light. One idea for suppressing the stray light is to shield the incident light on the peripheral region of the sensor chip by narrowing the FPA window. However, it is limited by the tolerance of assembly. In this study we have examined an epoxy coating on the peripheral region such as ROIC contact pad area, AlN substrate and bonding wire. Sensor chip with InGaAs/GaAsSb type-II quantum well structures, which has the cut-off wavelength of 2.35 μm, 320×256 pixels were bonded to ROIC through indium bumps, assembled to AlN substrate and to a four stage TEC. To avoid the degradation by the stress to the chip and bonding wire, low elastic modulus epoxy was selected. Stray light suppression was confirmed by the sensor signal output of epoxy coated samples, 3% contrast improvement was achieved. Further, reliability test of 10,000 heat cycles between -75°C and 25°C was carried out. No degradations were found in sensor characteristics of the epoxy coated sample. These results suggest that the epoxy coating in SWIR FPA is effective in suppressing the stray light and suitable for hyper spectral imaging.

Quantum cascade lasers (QCLs) are unipolar semiconductor lasers offering access to wavelengths from the mid-infrared (IR) to the terahertz domain and promising impact on various applications such as free-space communications, high-resolution spectroscopy, LIDAR remote sensing or optical countermeasures. Unlike bipolar semiconductor lasers, stimulated emission in QCLs is obtained via electronic transitions between discrete energy states inside the conduction band. Recent technological progress has led to QCLs operating in pulsed or continuous wave mode, at room temperature in single- or multi-mode operation, with high powers up to a few watts for mid-IR devices. This spectacular development raises multiple interrogations on the stability of QCLs as little is known on their dynamical properties. Very recently, experiments based on optical spectrum measurements have unveiled the existence of five distinct feedback regimes without, however, identifying the complex dynamics dwelling within the QCL. In this article we provide the first experimental evidence of a route to chaos in a QCL emitting at mid-IR wavelength. When applying optical feedback with an increasing strength, the QCL dynamics bifurcate to periodic dynamics at the external cavity frequency and later to chaos without an undamping of relaxation oscillations, hence contrasting with the well-known scenarios occurring in interband laser diodes.

GaAs related compound semiconductor heterostructures are one of the most developed materials for photonics. Those have realized various photonic devices with high efficiency, e. g., lasers, electro-optical modulators, and solar cells. To extend the functions of the materials system, diluted nitride and bismide has been paid attention over the past decade. They can largely decrease the band gap of the alloys, providing the greater tunability of band gap and strain status, eventually suppressing the non-radiative Auger recombinations. On the other hand, selective oxidation for AlGaAs is a vital technique for vertical surface emitting lasers. That enables precisely controlled oxides in the system, enabling the optical and electrical confinement, heat transfer, and mechanical robustness. We introduce the above functions into GaAs nanowires. GaAs/GaAsN core-shell nanowires showed clear redshift of the emitting wavelength toward infrared regime. Further, the introduction of N elongated the carrier lifetime at room temperature indicating the passivation of non-radiative surface recombinations. GaAs/GaAsBi nanowire shows the redshift with metamorphic surface morphology. Selective and whole oxidations of GaAs/AlGaAs core-shell nanowires produce semiconductor/oxide composite GaAs/AlGaOx and oxide GaOx/AlGaOx core-shell nanowires, respectively. Possibly sourced from nano-particle species, the oxide shell shows white luminescence. Those property should extend the functions of the nanowires for their application to photonics.

In this study, normal incidence polarization sensitive photodetector has been proposed based on intraband transition of holes in valence band using InGaAs/GaAs quantum dots. The in-plane elongated dots have been considered for the analysis to get the polarization sensitive absorption for normal incidence of light. The dimensions of the dots and transitions are chosen such that the peak detection wavelength comes in mid-infrared spectral region. We have calculated the detector parameters such as absorption coefficient, quantum efficiency, photoconductive gain, photocurrent and dark current. The calculated absorption coefficient and photoconductive gain are found of the order of 10⁴ m^-1 and 10⁵, respectively. The impact of number of quantum dot layers on these parameters has been analyzed. We have found that increasing the number of quantum dot layers enhances the quantum efficiency and decreases the dark current of the device, but simultaneously photoconductive gain reduces drastically and because of this photocurrent of the devices also reduces. In spite of very low quantum efficiency of the photodetector with single QDs layer, it can produce a significantly high detectable photocurrent due to large photoconductive gain of the device.

For the past several years there have been ongoing efforts to incorporate zinc oxide (ZnO) inside polymethyl methacrylate (PMMA), in the form of nanoparticles or quantum dots, to combine their optical properties for multiple applications. We have investigated a variation of atomic layer deposition (ALD), called sequential infiltration synthesis (SiS), as an alternate method to incorporate ZnO and other oxides inside the polymer. PMMA is a well-known ebeam resist. We can expose and develop patterns useful for photonics or sensing applications first, and then convert them afterwards into a hybrid oxide material with enhanced photonic, or sensing, properties. This is much easier than micromachining films of ZnO or other similar oxides because they are difficult to etch. The amount of ZnO formed inside the polymer film is magnitudes higher than equivalent amount deposited on a flat 2D surface, and the intensity of the photoemission suggests there is an enhancement created by the polymer-ZnO interaction. Photoemission from thin films exhibit photoemission similar to intrinsic ZnO with oxygen vacancies. These vacancies can be removed by annealing the sample at 500°C in an oxygen rich environment. SiS ZnO exhibits unusual photoemission properties for thick polymer films, emitting at excitations wavelengths not found in bulk or standard ZnO. Finally we have shown that patterning the polymer and then doing SiS ZnO treatment afterwards allows modifying or manipulating the photoemission spectra. This opens the doors to novel photonic applications.

Quantum sensing and metrology is the application of non-classical resources to the measurement of physical quantities with precision or accuracy beyond that allowed by classical physics. For many years non-classical resources such as atomic energy quantization, Josephson Effect, and Quantum Hall Effect have been used to define the fundamental units of time, voltage, and resistance, respectively. In recent years non-classical resources such as quantum squeezing and entanglement have been exploited to expand the range of physical phenomena measured with unprecedented precision or accuracy. We summarize some of the recent research on advanced quantum sensing and metrology and discuss our analyses of photon-added coherent states (PACS) of light. These analyses take into account imperfect photon addition and detection processes and show that PACS enable beyond-classical signal-to-noise ratio for photon counting even in cases where the probability of intended photon addition is 80%. We also show that there remains undiscovered fundamental properties of PACS related to their production and implementation.

Reflection, refraction, and absorption of light by material media are, in general, accompanied by a transfer of optical energy and momentum to the media. Consequently, the eigen-modes of mechanical vibration (phonons) created in the process must distribute the acquired energy and momentum throughout the material medium. However, unlike photons, phonons do not carry momentum. What happens to the material medium in its interactions with light, therefore, requires careful consideration if the conservation laws are to be upheld. The present paper addresses some of the mechanisms by which the electromagnetic momentum of light is carried away by mechanical vibrations.

According to remote sensing science and technology development and application requirements, quantum remote sensing is proposed. First on the background of quantum remote sensing, quantum remote sensing theory, information mechanism, imaging experiments and prototype principle prototype research situation, related research at home and abroad are briefly introduced. Then we expounds compress operator of the quantum remote sensing radiation field and the basic principles of single-mode compression operator, quantum quantum light field of remote sensing image compression experiment preparation and optical imaging, the quantum remote sensing imaging principle prototype, Quantum remote sensing spaceborne active imaging technology is brought forward, mainly including quantum remote sensing spaceborne active imaging system composition and working principle, preparation and injection compression light active imaging device and quantum noise amplification device. Finally, the summary of quantum remote sensing research in the past 15 years work and future development are introduced.

Time and frequency applications are in need of high accuracy and high stability clocks. Optically pumped compact industrial Cesium atomic clocks are a promising approach that could satisfy these demands. However, the stability of these clocks relies, among others, on the performances of the laser diodes that are used. This issue has led the III-V Lab to commit to the European Euripides-LAMA project that aims to provide competitive compact optical Cesium clocks for ground applications. This work will provide key experience for further space technology qualification. III-V Lab is in charge of the design, fabrication and reliability of Distributed-Feedback diodes (DFB) at 894 nm (D1 line of Cesium) and 852 nm (D2 line). LTF-Unine is in charge of their spectral characterisation. The use of D1 line for pumping will provide simplified clock architecture compared to the D2 line pumping thanks to simpler atomic transitions and a larger spectral separation between lines in the 894 nm case. Also, D1 line pumping overcomes the issue of unpumped “idle states” that occur with D2 line. The modules should provide narrow linewidth (<1 MHz), very good reliability in time and, crucially, be less sensitive to optical feedback. The development of the 894 nm wavelength is grounded on III-V Lab results for 852 nm DFB. We show here results from Al-free active region with InGaAsP quantum well Ridge DFB lasers. We obtain the D1 Cs line (894.4 nm) at 67°C and 165 mA (optical power of 40 mW) with a high side mode suppression ratio. The wavelength evolution with temperature and current are respectively 0.06 nm/K and 0.003 nm/mA. The laser linewidth is less than 1 MHz. The Relative Intensity Noise (RIN) and the frequency noise are respectively less than 10^-12 Hz^-1 @ f ≥ 10 Hz and 109 Hz²/Hz @ f ≥ 10 Hz.

We report the successful realization of quartz-enhanced photo-acoustic (QEPAS) sensors employing quartz tuning forks (QTFs) with novel geometrical parameters. We investigated the influence of QTF sizes on the main resonator parameters, in order to identify the best design parameters optimizing the QTF figures of merit for optoacoustic gas sensing. To evaluate the QTF acousto-electric energy conversion efficiency, we operated the QEPAS sensors in the near- IR and selected water vapor as the target gas. QTFs are forced to resonate at both the fundamental and the first overtone vibrational mode frequencies. Our results shows that two QTF designs exhibit an higher quality factor (and consequently an higher QEPAS signal) when operating on the first overtone mode with respect to the fundamental one.

We report the first demonstration of single-mode laser beam delivery in hollow-core waveguides (HCWs) operating in the 3.7-7.3 μm spectral range. We investigated the transmission properties of HCWs with 200 μm bore diameter and internal coatings properly designed to enhance the spectral response in the spectral range of 3-12 μm. We achieved single mode output throughout the 3.7-7.3 μm range. We measured a coupling efficiency < 90% and transmission losses as low as 1 dB, when using a 15 cm-long fiber at 3.7 μm under optimized coupling conditions between input beam and HCW.

Strong Shubnikov – de Haas (SdH) oscillations were observed in the derivative of microwave absorption (f = 10 GHz) in the InAs/GaSb/AlSb composite quantum wells (CQWs) using electron-paramagnetic-resonance spectroscopy at low temperatures (2.7–20 K) and in the magnetic field up to 14 kOe. CQWs were grown on the n-GaSb:Te(100) and n- InAs:Mn(100) substrates with various width of QWs by MOVPE. Predominance contribution of the bulk n-GaSb substrate in SdH oscillations was manifested. Two frequencies of the SdH oscillations were found from Fourier analysis, which is connected to warping of the Fermi surface of GaSb. Unusual angular indicatrix was observed in dependence on orientation of the samples in the magnetic field. Obtained results can be explained by inversion asymmetry, which is a feature of the substances with lack of inversion centres. For CQWs grown on n-InAs:Mn (n_s = 1.1 × 10¹⁷ cm^-3) substrate, only several SdH oscillations with higher period were observed. Taking into account isotropic Fermi surface of bulk InAs, we succeeded to extract a contribution of the 2D carriers of InAs QW ~ H⊥,where H⊥= H^constcosΘ, from bulk substrate oscillations using special spline interpolation from angular dependence of SdH oscillatory amplitudes in the angle range 0–90°. 2D electron concentration in the InAs QW ns ≈ 1 – 3 × 10¹¹ cm^-2 was evaluated from oscillatory period.

Ensembles of negatively charged nitrogen vacancy centers in diamonds are investigated as optical sensors for electric and magnetic fields in the interaction region of a neutron electric dipole moment experiment. As a first step towards measuring electric fields, the Stark shift is investigated in the ground electronic state, using optically detected magnetic resonance (ODMR) to measure hyperfine-resolved fine structure transitions. One detection approach is to modulate the electric field and demodulate the ODMR signal at the modulation frequency or its harmonic. Models indicate that the ratio of the amplitudes of these signals provides information about the magnitude of the electric field. Experiments show line shapes consistent with the models. Methods are considered for extending this technique to all-optical measurement of fields. Additionally, progress is reported towards an all-optical, fiberized sensor based on electromagnetically-induced transparency (EIT), which may be suitable for measuring magnetic fields. The design uses total internal reflection to provide a long optical path through the diamond for both the 637 nm EIT laser and a green repump laser.

Quantum cascade lasers (QCLs) are promising as compact light sources in the mid-infrared region. In order to put them into a practical use, their relatively high threshold currents should be reduced. Facet reflectivity increase by distributed Bragg reflector (DBR) is effective for this purpose, but there have been few reports on DBR-integrated QCLs (DBRQCLs). In this paper, we report a successful operation of a DBR-QCL in 7 μm wavelength region. With the fabrication, an n-InP buffer layer, a core region consisting of AlInAs/GaInAs superlattices, an n-InP cladding layer, and an n-GaInAs contact layer were successively grown on an n-InP substrate using OMVPE in the first growth. Then, the wafer was processed into a mesa-stripe, and it was buried by an Fe-doped InP current-blocking layer to form a buriedheterostructure (BH) waveguide. After that, a DBR in which semiconductor-walls and air-gaps were alternately arranged was formed at the front or end of the cavity by dry-etching the epitaxial layers of the air-gap regions, and thus a DBRQCL was fabricated. A DBR-QCL chip (Mesa-width:10 μm, Cavity-legth:2 mm) which had a DBR-structure consisting of 1 pair of a 3λ/4-thick semiconductor-wall/3λ/4-thick air-gap at the front end and a high reflective facet at the rear end oscillated successfully under continuous-wave condition at 15°C. This is the first report on the InP-based DBR-QCL to our knowledge. The facet reflectivity at the DBR was 66%, which was about two times larger than that of the cleaved facet. This result clearly shows that the DBR-structure is effective for threshold current reduction of QCL.

We discuss the numerical simulation of high current density InGaAs/AlAs/InP resonant tunneling diodes with a view to their optimization for application as THz emitters. We introduce a figure of merit based upon the ratio of maximum extractable THz power and the electrical power developed in the chip. The aim being to develop high efficiency emitters as output power is presently limited by catastrophic failure. A description of the interplay of key parameters follows, with constraints on strained layer epitaxy introduced. We propose an optimized structure utilizing thin barriers paired with a comparatively wide quantum well that satisfies strained layer epitaxy constraints.