Recent studies have shown that the incorporation of scandium (Sc) can transform AlN to be ferroelectric. The resulting ferroelectric ScAlN exhibits significantly enhanced electrical, piezoelectric, as well as linear and nonlinear optical properties. These unique characteristics, together with its ultrawide bandgap, ferroelectric functionality, and seamless integration with III-nitride technology, have made ScAlN a very promising platform for future integrated quantum photonics. Here, we report on the epitaxy of single crystalline ferroelectric ScAlN and the demonstration of ScAlN waveguides, ring resonators, and modulators, which offer, for the first time, the ability to truly unlock the potential of this material system.

The inherent causes of the efficiency droop and low current density at the onset of the efficiency droop in green hexagonal-LEDs (h-LEDs) and cubic-phase InGaAlN LEDs (c-LEDs) are investigated with a new Open Boundary Quantum LED Simulator (OBQ-LEDsim). The coexistence of strong internal polarization and large carrier (i.e. electron and hole) effective mass induces strong Auger recombination that causes the large performance rollover in h-LEDs. On the opposite, in c-LEDs, the absence of internal polarization together with smaller carrier effective mass weakens Auger recombination, which quenches the droop by ~51%. These findings point at new ways to improve the performances of green LEDs.

We report our study on the enhanced light extraction efficiency (LEE) of the 280nm AlInN nanowire ultraviolet light-emitting diodes (LEDs) using different surface passivation approaches and photonic crystal structures. With a ~ 30nm Si3N4 as surface passivation, the AlInN LED could achieve relatively high LEE of ~ 41.5%, while the unpassivated LED has an average LEE of ~ 23.5%. Moreover, the periodically arranged nanowire LED arrays in hexagonal structure exhibit high LEE of 61.4% which is almost two times higher compared to that of the randomly arranged nanowire LEDs. Additionally, the AlInN nanowire ultraviolet LEDs show highly transverse-magnetic polarized emission.

GaN and related materials span one of the largest ranges of band gap energies of any III-V alloy system, from the mid-infrared to deep ultraviolet. In addition, its asymmetric crystal polarity creates regions of negative dielectric constant in the deep infrared. This talk will describe our work in combining this band gap flexibility with precise dimensional and positional control of 3D nanostructures via selective epitaxy in plasma-assisted molecular beam epitaxy. Applications range from microLEDs to optical interconnects to metamaterials.

A high efficiency, micrometer or submicron scale light emitting diode (LED) is essentially required for the emerging virtual reality and augmented reality. However, conventional LED fabrication methods suffer from a large drop in efficiency on scaling the device size. In this work, we report a N-polar InGaN nanowire micro-scale LED emitting efficiently in the red spectrum. A peak external quantum efficiency of ~1.2% is measured for LEDs emitting at 620nm, with lateral dimensions ~750nm: consisting of just 6-7 InGaN nanowires. This efficiency value is nearly one order of magnitude higher than conventional quantum-well micro-LEDs of similar dimensions operating in this wavelength range.

In this work, we demonstrate a new sensing modality of a field-deployable mid-infrared quantum cascade laser dual-comb spectrometer with a raster-scan setup for collecting hyperspectral images of contaminated surfaces from a distance.

We present a high-performance planarized waveguide THz quantum cascade laser frequency comb, where an inverse-designed active waveguide front facet with a reduced reflectivity is coupled to a patch array antenna, and all the components are optimized for an octave-spanning emission spectrum (2-4 THz). Broadband frequency comb states spanning over 800 GHz with a single narrow RF beatnote up to -50 dBm are measured at 20 K. The slope efficiency is improved by around five times, with a peak output power of 13 mW in pulsed mode (10% duty cycle at 20 K). Far-field measurements of the surface emission display a narrow symmetric pattern with a beam width of (21° x 20°).

This conference presentation was prepared for SPIE OPTO, Photonics West, 2023.

We report the polarization, the interference far-filed pattern, the multimodal spectral emission and the power extraction of the emitted beam from a set of electrically-pumped random quantum cascade lasers in the terahertz range. By integrating, on chip, a non-linear multilayer graphene stack with the laser gain medium, we demonstrate self-induced phase-coherence between the naturally incoherent random modes. We then employ the devised random laser in a detectorless near-field imaging system, exploiting the intracavity reinjection of the laser field via self-mixing interferometry in a confocal microscope for speckle-free tomography with nm-size resolution

We demonstrate the first-ever hyperspectral s-SNOM imaging system, providing 160nm spatial resolution, coherent detection of multiple phase-locked modes and mapping of the THz optical response of nanoscale materials such as topological insulators in the 2.29-3.60 THz range with noise-equivalent-power ~400pW/√Hz, relying on a 6mW comb-emitting THz QCL. We provide near-field images of Bi2Se3 and Bi2Te3 and their spectroscopic characterization in a >1 THz optical bandwidth extracting their optical contrast response through the application of the synthetic optical holography technique.

We present low threshold quantum cascade surface emitting lasers (QCSELs) emitting at wavelengths of 4.5 micrometers or 8 micrometers. To extract the light vertically from the InP-based buried heterostructure laser a second order InGaAs/InP grating is used. Both ridge facets are formed by dry-etching followed by coating a dielectric-metal film. Due to the high reflectivity of the facets, the cavity can be shortened well below 500 micrometers reducing the threshold power to several hundred milliwatts. The proposed device concept allows large-scale fabrication and wafer-level characterization. The results are an important step towards low-cost and low-power consuming quantum cascade lasers for portable MIR gas sensors.

Mid-infrared chemical sensors based on quantum cascade (QC) devices offer improved sensitivity, portability and costs compared to FTIR-based spectrometers. In this work, we combine for the first time a broadband external-cavity QC laser (EC-QCL) with a spectrally tailored QC detector (QCD) for broadband detection of bovine milk proteins including β-lactoglobulin, α-lactalbumin and casein. We analyze concentrations between 0.25-15 g/L in a 12.5-µm transmission flow cell in the amide-I and -II band (~1730-1470 cm-1) and obtain: a RMS noise-level of 0.067 mAU, a limit-of-detection of ~0.09 g/L, excellent agreement with FTIR absorbance-spectra and similar performance as much more bulky high-end FTIR-spectrometers.

We present the fabrication and operation of GaN vacuum nanodiodes that operate in air and exhibit ultra-low turn-on voltage, high field emission current, excellent on-off ratio, and promising reliability and radiation hardness. Experimental and modeling results on the characteristics of these devices at various nanogap sizes, operating pressures, and radiation environments are discussed. Preliminary results on the fabrication and characteristics of lateral GaN nano vacuum transistors will also be shown. These results provide key new insights into the behavior and potential of this new class of devices and point to future challenges and opportunities. Sandia National Laboratories is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.

In this paper we discuss how a combination of band structure and band alignment engineering may be used to reduce the temperature sensitivity of semiconductor lasers operating in the near-IR. The use of back-to-back type-II band alignment “W”-structures, already successfully demonstrated in the mid-IR, provides a route to engineer the temperature sensitivity of the emission wavelength in near-IR devices through control of the band gap and band bending. Furthermore, utilising novel alloys such as the bismide-nitrides also provides a route to reduce non-radiative processes which underpin the temperature sensitivity of the threshold current across this wavelength range.

We show by numerical modelling how geometrical parameters of a NW and Si-WG design influence the spontaneous emission enhancement of the QD emitter and the in-coupling efficiencies at the NW-WG interface. First experiments towards the development of an integrated III-V NW-QD system are then presented. Here, we demonstrate a droplet-free site-selective epitaxy of vertical-cavity NW waveguides, where good control of GaAsSb/InGaAs axial heterostructures and their distinct luminescence properties are demonstrated. We also discuss control of Indium incorporation into the InGaAs axial segment, to tune the emission wavelength before optimizing the axial size, progressing towards an axial QD.

We present recent advances in the development of magnetic memory devices based on antiferromagnetic (AFM) materials. We show strategies for electrical control of the magnetic order (i.e., writing of information) in AFM materials using spin-orbit torque, and discuss their experimental demonstration in devices based on multiple AFM metals [1, 2]. We then discuss perspectives for electrical readout of information from AFM materials, which, due to the absence of a net macroscopic magnetization, has long been considered impractical. This is a grand challenge requiring new approaches to the realization of large magnetoresistive (MR) effects in tunnel junctions involving AFM thin films, where electrical reading and writing operations can be integrated for memory and computing applications. We will discuss recent theoretical proposals and experimental progress in the development of such devices. [1] Shi et al., Nature Electron., 3, 92 (2020) [2] Arpaci et al., Nature Comm., 12, 3828 (2021)

This conference presentation was prepared for SPIE OPTO, Photonics West, 2023.

We demonstrate ultrawideband mmWave waveform generation based on optical frequency combs and additive frequency synthesis. We generate an electro-optic frequency comb, apply fine amplitude and phase control to pairs of comb lines (beat notes), and demultiplex the beat notes to multiple uni-traveling carrier photodiodes, which are connected on-wafer to a mmWave frequency combiner. Using multi-tier microwave S-parameter and power calibrations, we demonstrate on-wafer mmWave power levels up to +12.7 dBm and fine amplitude and phase control with 0.1 dB and 25 mrad resolutions respectively. We apply this fine resolution to arbitrary waveform generation with 100 GHz of instantaneous bandwidth on a single photodiode. We also summarize new results with five photodiodes connected to an on-wafer frequency combiner and our efforts to integrate NIST’s high-power amplifiers up to 500 GHz and beyond.

We investigate the use of period-doubling perturbations for switching on / off absorptive and emissive processes in microstructured materials. We first design periodic gratings to support guided resonance modes that enhance absorption in the vicinity of the resonance wavelength. We then introduce a refractive index perturbation that effectively doubles the period of the original grating. Given proper design, we can introduce a photonic band gap at the edge of the new Brillouin zone, "erasing" the original resonance mode at the operating wavelength. We discuss applications to electrically-modulated emissive control in both visible-wavelength, photoemissive and infrared-wavelength, thermally emissive structures.

As the efficiency of mid-infrared LEDs has advanced, they have assumed increasing importance in sensitive gas optical sensors, most prominently for methane and carbon, and LED arrays for defense-related projection systems. While cascading and superlattice quantum design has advanced efficiency, a key limiting mechanism in these devices is heavy loss from total internal reflection due to the very high index of refraction (~3.8). Here we report on the substantial enhancement of spectral radiance in one- and two-color LED emitters using a microcavity approach, and enhancement in overall radiance of single color emitters using micropillar structured devices.

Applications of gallium nitride LEDs beyond general illumination will be discussed including microdisplays, tactile sensors for robotics, on-chip ultralow profile spectrometer, single photon sources, and spin qubit gates.

Monolithic integration of InAs/InAsSb type-II superlattice (T2SL) photodetector on large-scale Si wafers would allow the development of a low-cost, high-quality, Si-readout integrated circuit compatibility focal plane array (FPA). In this study, we compare the performances of MWIR InAs/InAsSb T2SL samples grown on Si and GaSb substrates. The material quality is investigated with High-Resolution X-ray Diffraction, Atomic Force Microscopy, and Photoluminescence (PL). A minority carrier lifetime of 800 ns at 150 K is extracted from time-resolved PL on the sample grown on GaSb/Si templates with dislocation filtering layers. The device performances will be reported at the conference.

THz polarimetry is an emerging area that has applications in materials imaging and spectroscopy. Thus, there is a growing need for compact sensors with the ability to record complete polarization information from few-cycles pulses of THz radiation. We have exploited the unique geomatical and electrical properties of semiconductor nanowires to develop monolithic polarization-resolving THz sensors. We demonstrate these sensors in a range of applications from the analysis of polarization-manipulating metamaterials to semiconductor characterization and THz imaging. Our nanowire platform also shows promise for other THz photonic devices.

Hyperspectral imaging has attracted significant attention to identify spectral signatures for image classification and automated pattern recognition in computer vision. State-of-the-art implementations of snapshot hyperspectral imaging rely on bulky, non-integrated, and expensive optical elements, which do not allow fast data processing, e.g., real-time and high-resolution videos. This work introduces Hyplextm, a CMOS-compatible, fast hyperspectral camera that replaces bulk optics with suitably designed artificial intelligent optical hardware components. Hyplextm does not require spectrometers but uses conventional monochrome cameras, allowing real-time and high-resolution hyperspectral imaging at inexpensive costs. In this invited talk, we discuss the design, implementation, and real-world applications of Hyplextm.

We report the room-temperature frequency response, in the range 0-220GHz, of GaAs-based QWIP photodetectors operating at 10um. Detectors rely on 2D arrays of patch-antennas, connected to an integrated 50-Ohm coplanar line allowing on-wafer characterization. By difference frequency mixing of two QCLs, we obtain a RF 3dB bandwidth of ~90GHz. The frequency response of devices based on 4 antennas is compatible with a carrier capture-time of ~2.5ps. By replacing the coplanar line with a log-spiral antenna we also demonstrate devices radiating directly in free-space. The perspective of exploiting the latter as QCL-pumped photomixers for the generation of microwave/sub-mm radiation is discussed.

In the race to demonstrate a scalable and fault tolerant quantum computing (QC) platform, quantum photonics stands poised to have a major impact. In particular, by encoding quantum information over fields rather than photons (continuous-variable—CV, rather than discrete-variable—DV, quantum information), record-size quantum processors were demonstrated in spectral and in temporal quantum field combs. These demonstrations used the measurement-based QC paradigm, which is based on cluster entangled states. In this talk, I will outline two of our recent results: proposals for generating hypercubic cluster states by phase modulation of the quantum optical frequency comb and for generating fault-tolerant hybrid CV-DV encodings called Gottesman-Kitaev-Preskill states. The latter leverages CV cluster states along with our experimental ability to perform photon-number-resolving measurements up to 100 photons.

Two-dimensional semiconductors prepared from van der Waals crystals of transition metal dichalcogenides are a burgeoning area of research with unique layer-dependent optoelectronic properties. Atomically precise junctions can be assembled by mechanically placing two such semiconductor monolayers on top of each other without any constraints of epitaxy or covalent bonding. In this talk I will describe our efforts to uncover the role of layer-hybridized electronic states as a powerful route to control ultrafast energy transport across such 2D heterojunctions by using a combination of ultrafast electron diffraction thermometry and first-principles calculations. Our experiments and theory present a new understanding of the microscopic origins of ultrafast charge and energy transport across two dimensional heterostructures.

Plasmonic and dielectric nanostructures provide numerous opportunities for designing optical response for nonlinear, chiral and quantum applications. Combining dissimilar plasmonic and dielectric materials in one nanostructure offers additional prospects for devising optical properties and achieving functionalities not attainable otherwise. In this talk, we will discuss hetero-nanostructures for tailoring nonlinear and chiral optical properties beyond traditional field enhancement effects. This allows controlling hot-electron relaxation, tuneable opto-acoustic response and chiral coupling important for nonlinear photonics and sensing applications.

Donors in silicon is a potential scalable qubit platform for quantum technologies due the compatibility with existing microelectronic fabrication. Bismuth donors are particularly interesting due to their large nuclear spin and strong hyperfine coupling, manifesting as a 20-dimensional Hilbert space with a hyperfine splitting of 30.5 µeV which can be resolved without the application of a magnetic field. Fully scalable manufacturing of deterministically positioned donors can only be achieved through single ion implantation. Here we will present a review of our recent optical characterisation studies of implanted Bi donors which address the challenges of by the implantation route for the delivery of usable materials for quantum technologies.

Color centers in nanodiamonds coupled to nanophotonic structures feature unique properties to realize high-bandwidth quantum photonic devices. They exhibit photostable and narrowband single-photon emission. Their natural compatibility with plasmonic resonators unlocks a giant enhancement of light-matter interaction and photon emission rates up to the THz range. Color centers in nanodiamonds can be integrated onto any robust photonic platform. However, the sizes of nanodiamonds and the heterogenous properties of color centers pose challenges for device fabrication. Recently, innovative methods for nanodiamond growth, large-scale screening, and deterministic nanoparticle transfer have been developed. In this context, we will zoom in on our recent demonstrations of rapid techniques for large-scale optical screening of quantum emitters, including automatic confocal microscope focusing in a noisy environment and nanodiamond sizing.

AlN as an UWBG host for quantum emitters, especially color centers, is expected to address current challenges such as operation at room temperature and scalability of quantum-photonic devices for qubit applications. Significant challenges in the point defect management and existence of multiple defects charge states precludes the use of AlN as a simple practical host for qubits. In this work, a roadmap for the stabilization of Ti-related color centers in AlN for quantum computing applications is presented. The realization of (TiAlVN)0 defects as a candidate for single spin color center requires the control of the Fermi level of AlN via doping, a nitrogen vacancy supersaturation via implantation, and the use of CPC and dQFL control methods to suppress the formation of other defects. This work opens a pathway for the systematic management of color centers with particular charge states in nitrides for quantum computing applications.

There is an increasing demand in the realization of new color centers in ultrawide bandgap semiconductors with ability to operate at room temperature for the quantum computation. AlN with bandgap of 6.2 eV and availability of mature growth techniques and controllable doping seems to be a suitable host for many deep color centers as a candidate for qubit such as (Ti_Al-V_N)^0. However, stabilization of this defect configuration with certain charge state requires defect engineering in AlN. In this work, formation of Ti-V complex was enhanced by introducing nitrogen vacancy supersaturation through Ti implantation. Kinetics of Ti-Vacancy complex formation was studied by annealing the implanted samples at various temperatures. Furthermore, the structural and optical properties of these color centers were investigated via STEM and micro-PL measurement. This work opens up pathway for realization of any color centers in semiconductors as a candidate for qubit.

This conference presentation was prepared for SPIE OPTO, Photonics West, 2023.

A wide variety of methods, primarily computational, are currently used to enhance images and extract information from them. With the rapid increase in the amount of data being generated, however, there is a renewed interest in all-optical methods for replacing or facilitating digital approaches to enhancing images of amplitude or phase objects. Well-established all-optical methods for real-time image processing typically require the use of comparatively bulky optical creating a roadblock for their incorporation into state-of-the-art miniaturized optical systems. Here, the use of nanophotonics for enhancing images of amplitude and phase objects will be presented. A particular focus will be systems that exhibit an asymmetric optical transfer function permitting a broader range of processing operations and contrast enhancement strategies than accessible with symmetric systems.

Though near-infrared spectroscopy (NIRS) has been used to noninvasively measure human physiology for over 40 years, most NIRS devices ignore spatial and temporal variations in tissue optical scattering. Alternatively, temporally and spatially-resolved NIRS, in either the real or frequency domains, allows for direct measurements of tissue optical scattering and thus the ability to make direct measurements of tissue composition and oxygen metabolism. In this tutorial presentation, I will give an overview of the technology and applications of quantitative deep tissue optical spectroscopy, with a focus on how new photonics technologies are improving the performance and accessibility of these techniques.

In this contribution, we will report on a novel technique recently developed at Institut Langevin that enables multiplexed and super-resolved fluorescence lifetime imaging at the single-molecule level (smFLIM) with a field of view of ~10 µm2 and a localization precision of ~15 nm. Our method combines the use of an EMCCD camera for the localization of photoactivatable single molecules (as usually done in SMLM) and a linear array of single-photon avalanche diodes (SPADs) for time-resolved measurements. Our method can be used for LDOS imaging of disordered and deterministic structures with nanometer-sized features and extensions going from a few hundred nanometers to several microns, with a dynamic temporal range spanning from ns to ms. We will show how smFLIM allows the study of simple nanostructures such as a silver nanowire and complex nanostructures, such as periodic arrays of hollow gold truncated nanocones (nanochimneys).

Fast and non-invasive screening test based on electrochemical detection of structural proteins of SARS-CoV-2 was developed. The measurement being the basis of the test is carried out in a standard three-electrode system, in which the working electrode is covered by bioreceptors immobilized on its surface by durable covalent bonding, ensuring specificity of the detection of desired analyte present in the sample. The carried out measurements allowed for detection of given protein of SARS-CoV-2 in standardized buffered samples and in samples containing virus-like particles. The estimated detection limit of the biosensor does not exceed 10^5 copies of the virus per milliliter.

In this talk, I will describe a novel fabrication method based on DNA-assembly of gold nanoparticles on a substrate, which can be used to design passive and active nanophotonic metamaterials and metasurfaces. In particular, we have demonstrated wide range of functional nanophotonic device architectures including epsilon-near-zero metasurfaces, negative index metamaterials and broadband absorber metafilms. The synthesis of plasmonic NP architectures with structures and stimuli-responsive behavior that are not accessible in lithographically-defined plasmonic nanostructures provides an opportunity to design materials with emergent optical properties that offer new fundamental insights and previously inaccessible functionalities.

This conference presentation was prepared for SPIE OPTO, Photonics West, 2023.

Organophosphorous compounds, e.g., sarin, are known for their harmful effects towards human. We propose a rapid chemistry-free III-V semiconductors InAsSb plasmonic transducer working in the mid-infrared with ribbon-shaped nano-antennas associated with a confined enhanced electric field at the nanoscale. Exploiting Salisbury perfect absorber structure coupled to an epsilon-near-zero layer benefit both spectral and spatial overlap for efficient surface-enhanced infrared spectroscopy (SEIRA). A detection signal close to 5% was obtained allowing us to estimate that a 5 Å thick monolayer of the sarin simulant DMMP has bound to the sensor native oxide. FDTD and RCWA simulations confirmed experimental results.

There will be overviewed our recent results on engineering the electronic and optical properties of InGaAs/GaAs and InAs/InP quantum dots suitable for single photon emitters in the 1.3-1.55 µm range. There will be discussed the issues of single photon emission purity and its temperature stability in relation to the underlying physics of the confined excitonic complexes and in view of fundamental limitations of the fabrication technologies, as well as engineering the photonic confinement for controlling the emission rates, emission polarization and light collection efficiency. Eventually, there will described a solution for constructing stand-alone, cryogenic-free fiber-coupled sources operating at telecom wavelengths.

Single core/shell CdSe/CdS colloidal nanocrystals are usually used as efficient single photon sources working at room temperature, with a narrow spectrum of =30nm. For large shell, they evidence a strong resistance to high excitation and can withstand a few 106W/cm2,. Under high excitation their emission change dramatically, emission evolves non linearly with laser excitation power and the spectrum range can reach a few 100nm. In order to understand such a behavior, we use a statistical description of the electrons and holes population as fermi dirac distributions, followed by radiative recombination of excitons, which describes well experimental results.

Subwavelength metamaterial nanounits can efficiently harvest electromagnetic (EM) waves, resulting in near unity light absorption in the narrow or broad frequency range. For this purpose, we explored the material and architecture requirements for the realization of light perfect absorption using these metamaterial designs from ultraviolet (UV) to far-infrared (FIR) wavelength regimes. This, in turn, opens up the opportunity of the practical application of these perfect absorbers in large scale dimensions. We adopted these lithography-free techniques in many applications including photoelectrochemical water splitting, photodetection, light emission, sensing, filtering and thermal camouflage. This presentation will summarize our recent accomplishments in scalable photonic and photoelectronic designs for various applications.

Excitons are quasi-particles found in semiconductors that are bound together by the coulombic interaction between an excited electron and a hole. They play an essential role in the working of commercial optoelectronic devices such as displays, solid state lighting and solar cells as well as natural processes such as photosynthesis. In this talk, I will discuss our group’s effort towards understanding and controlling the excitonic energy dynamics at hybrid interfaces formed between organic semiconductors and transition metal dichalcogenides (TMDs) monolayers. I will also showcase the implementation of such hybrid interfaces in assured electronics as well as in nanoelectronics. Such van der Waals interfaces present an opportunity to develop a new class of hybrid semiconductors with superior electronic, optical, magnetic and chemical properties that can be exploited for next-generation applications in photovoltaics, light generation, and data processing.

ASELSAN A.S. is not only the largest defense company but also the biggest R&D spender in Türkiye. In line with the company policies on R&D, the R&D Vice Presidency has been founded on Janaury 1st, 2021 with the vision of “Developing advanced and disruptive technologies in the field of ASELSAN activities and to be a pioneer in the global position.” The main research activities at R&D Vice Presidency includes but not limited to biosensors, sensors, quantum devices, artificial intelligence, communication, photonics, autonomy and advanced materials. This talk will summarize the latest results/developments on these topics.

In this talk, I will discuss about the recent progress made on the development of continuous-wave operating electrically-pumped InP-based topological insulator lasers at 1.55 µm. Two-dimensional (2D) arrays of ring resonators are employed for implementing such diode lasers which are expected to inherently harness the features of topologically-protected transport to force many semiconductor emitters to phase-lock together and behave as a single powerful highly-coherent laser source. Results related to degree of disorder obtained from conventional microfabrication technologies and its impact on topological lasing will be presented. The influence of dry etching and the associated surface recombination on deeply etched ring structures will also be discussed.

Modulation spectroscopy enables the investigation of weak infrared radiation signals produced by sources with size is in the micrometer range. We have used this method first to investigate the thermal radiation from single subwavelength sized metallic or dielectric resonators. Next, we have adapted our setup to investigate the radiation from transistors made of graphene microstructures encapsulated in boron nitride (hBN). It is shown that the infrared emission from these devices exhibits features which are typical for electroluminescence and is concomitant with the occurrence of Zener Klein tunneling.

We introduce an inverted refractive-index-contrast grating (ICG) that is a compact alternative to DBRs. In ICG a subwavelength grating made of a low refractive index material is implemented on a high refractive index cladding. We experimentally demonstrate high reflectivity of proof-of-concept ICG fabricated by 3D microprinting, in which IP-Dip photoresist grating is deposited on silicon cladding. We also show that the ICG provides nearly total optical power reflectance whenever the refractive index of the grating exceeds 1.75, irrespective of the refractive index of the cladding.

Our work is focused on the development of an efficient class of scalable, low cost and integrated elements for light polarization control in the mid-infrared. We investigated vanadium dioxide (VO2) a thermocromic material showing a semiconductor to metal transition at 67°C as well as alpha-molybdenum trioxide, a Van der Waals material displaying strongly anisotropic behavior in the infrared. We will show the single materials spectral response in the IR range and then we will highlight how the use of combined multilayer structures can allow the tunability of spectral features of the resulting structure to get IR radiation management.

We report the demonstration of electrically pumped Terahertz quantum cascade lasers based on topologically-protected valley edge states. Unlike previous topological lasers that relied on large-scale features to realize topological protection, we employ a compact valley photonic crystal design analogous to two-dimensional (2D) gapped valleytronic materials. Lasing occurs in a sharp-cornered triangular cavity with whispering gallery propagating modes. In addition, we experimentally demonstrate the electrically pumped topological lasers in a Majorana zero mode which shows a cylindrical vector beam single-mode lasing emission in the Terahertz regime.