The presentation will cover the recent and current programs within the National Science Foundation that support advances in Photonics, from fundamentals to applications.

Direct digital receivers operating up to millimeter wave frequencies are desired for telecommunications, instrumentation, and surveillance, as analog received signals are digitized for high performance signal processing. The Analog-to-Digital Converter (ADC) is a vital component in detection systems. The ADC samples analog signals at discrete time intervals with a finite resolution and outputs a digital code to represent the signal. The Nyquist sampling time interval is determined by the ADC sample clock, fs, while the resolution is determined by the effective number of bits (ENOB) of the ADC. Timing jitters of electronic clocks have limited ENOB, as while self-forced opto-electronic oscillators have demonstrated a greater frequency stability as lows as 11fs at K-band. ADC performance requirements are identified in terms of Walden figure of merit (FOM). Integrated concept of opto-electronic based all-optical ADC has been introduced [3] as shown in Figure 1. A high signal to noise is maintained for all deflected angles. With current performance predictions of 9.4 ENOB at 40GSPS and under 230mW wall-plug power, the FoM is then 8.5 fJ/conv-step, which is better than the best reported FOM of 75 fJ/conv-step for an electrical ADC with speed of 2GSPS, 5.7 ENOB, and power of 2.3mW.

This conference presentation, originally published on 9 March 2024, was withdrawn on 12 April 2024 per author request.

Ultrawide bandgap semiconductors offer a promising shift from silicon-based power electronics, catering to more efficient and compact alternatives in applications like next-gen power grid controls, ultrafast electric vehicle charging, high-voltage power converters, and beyond. However, current power systems using III-Nitride materials face challenges due to high defect density and low operating efficiencies, stemming from the absence of commercially viable native substrates. Gallium Oxide (Ga2O3), a novel material, emerges as a solution with native substrates and favorable properties such as an ultrawide bandgap and high critical electric field. Integrating Ga2O3 with III-Nitride materials is expected to harness the high critical electric field and native substrates in Ga2O3, combined with the superior thermal conductivity of III-Nitride. This study reports the first epitaxial growth of N-polar III-Nitride/Ga2O3 heterogeneous heterostructures, showcasing enhanced material qualities, especially in electron mobility. This breakthrough enables the development of power transistors with a 10X increase in power density, addressing size, weight, and power power constraints in applications

The design of transparent conductive electrodes (TCEs) for optoelectronic devices requires a trade-off between high conductivity or transmittivity, limiting their efficiency. This paper demonstrates a novel approach to fabricating TCEs: a monolithic GaAs high contrast grating integrated with metal (metalMHCG). The technology and influence of fabricated different configurations of metalMHCG on the optical parameters will be shown. We will demonstrate above 90% absolute transmittiance of unpolarized light, resulting in 130% transmittance relative to plain GaAs substrate. Despite record high transmittance, the sheet resistance of the metalMHCG is several times lower than any other TCE, ranging from 0.5 to 1 OhmSq−1.

This talk will discuss electric-field-controlled magnetic tunnel junction (MTJ) devices for magnetic random access memory (MRAM), which utilize the voltage-controlled magnetic anisotropy (VCMA) effect for switching. We present the first VCMA-MRAM devices with sub-1V write voltage, based on perpendicular MTJs with record-high VCMA coefficients (~130 fJ/Vm), high tunnel magnetoresistance ratio (TMR > 150%), and small bit diameters of 30 to 70 nm [1]. Next, we discuss the application of these VCMA-MRAM bits for applications ranging from true random number generation to machine learning [2], physically unclonable functions [3], and implementation of probabilistic computers to solve hard optimization problems [4]. As an example of the latter, we demonstrate solution of 40-bit integer factorization problems on Ising machines that utilize experimental stochastic bitstreams from VCMA-controlled MTJs. [1] Y. Shao et al., Communications Materials 3, 87 (2022) [2] Y. Shao et al., IEEE Magnetics Letters 12, 4501005 (2021) [3] Y. Shao et al., Advanced Electronic Materials, 2300195 (2023) [4] Y. Shao et al., Nanotechnology, doi: 10.1088/1361-6528/acf6c7 (2023)

Topological insulators (TI) based on InAs/GaSb quantum wells are appealing due to their rich phase diagram with a topological and normal insulating phase. Due to the spatial separation of electrons and holes in the InAs and GaSb layer, respectively, a switching between both phases can be achieved by external electric fields using a top and back gate. We present another tuning knob using optical excitation. By monitoring the charge carrier densities, we can identify the hybridized band structure and in-plane magnetic field measurements evidence the TI gap. We will discuss how the interplay of negative photoconductivity and persistent charge carrier buildup leads to the tuning of the phase diagram by optical excitation.

This talk reviews the research on InAs/InAsSb type-II superlattices and applications to IR lasers and photodetectors with the following highlights: 1) Review of the study of InAs/InAsSb T2SL and its application to IR lasers and photodetectors in the 90’s. 2) Long minority carrier lifetimes were observed in MWIR and LWIR InAs/InAsSb T2SL. 3) Pressure-dependent photoluminescence experiments were conducted on a MWIR InAs/InAsSb T2SL structure to provide evidence for a defect level above the conduction band edge of InAs. 4) First InAs/InAsSb T2SL nBn photodetectors were demonstrated to cover both MWIR and LWIR bands. 5) Hole mobilities were measured.

Highly sensitive infrared photodetectors are needed in numerous sensing and imaging applications. In this paper, we report strong light-matter interaction at a quantum dot (QD) scale and the induced significant enhancement in photosensitivity and quantum efficiency. A plasmonic perfect absorber (PPA) cavity is fabricated with embedded quantum dots. The PPA cavity is designed to resonate with the intersubband transitions in quantum dots. The E-field overlaps with the QDs plus the energy resonance induce the strong light-matter interactions. Detailed analysis and experimental results will be presented.

This talk reports the operation principles and preliminary demonstration of monolithically integrated optically-addressed multiband PDs using GaSb and latticed-matched InAs/InAsSb type-II superlattices (T2SLs) to cover SWIR, MWIR, and LWIR detection ranges. The design minimizes the number of terminals so that it greatly reduces the complication of layout and device processing and ROIC complexity when implementing the photodetectors into an FPA. Details of device fabrications, characterization, modeling and performances such as dark current, spectral responsivity, and cross-talk will be presented.

A compact assembly of photodetectors, incorporating specialized surface nanostructures, holds the potential to significantly enhance imaging capabilities by acquiring multi-dimensional data, including spectral profiles, temporal responses, and spatial resolution. This advancement is achievable by engineering individual ultrafast detectors exhibiting distinct responses to identical illumination while leveraging artificial intelligence (AI)-driven computational imaging. This talk will demonstrate how these capabilities can substantially miniaturize the physical dimensions of existing imaging and spectroscopic systems and elevate overall system sensitivity. These advancements can be applied to various fields, including noninvasive real-time detection and monitoring of molecules for medical diagnostics, biological sensing, and food quality assessment.

Nanostructures are integrated with CMOS image sensors to enable measurement of multimodal light information including incident angle, spectral and phase front information. Millions of measurement can be performed at the same for high spatial resolution.

INVITED Talk Owing to its intrinsically large and electrically tunable non-linear optical response, graphene has recently been adopted as a core nanomaterial for such multiple optical harmonic generation at frequencies < 2 THz. By employing engineered nanostructures to funnel light into small volumes and hence intensify the nonlinear optical processes with spectral and spatial control, emission in the 12 – 5 THz range, can potentially be addressed. This important frequency range currently lacks a practical laser technology because the Restrahlenband of common III-V semiconductors prevent the development of a solid-state laser using these materials. In this talk I’ll report on generation of light at 9.63 THz by optically pumping a graphene circular split ring resonator (CSRR) array with a high-power, 3.21-THz-frequency quantum cascade laser. The mode confinement provided by the optically-pumped CSRR enhances the pump power density, allowing third harmonic generation in a frequency range where compact sources do not currently exist, opening a plethora of novel application fields.

Terahertz radiation is becoming increasingly important for a broad range of (potential) applications. However, photonic applications are typically more advanced in other regions of the electromagnetic spectrum than in the terahertz region. During the past years, it has become evident that quantum materials with massless electrons, such as graphene and topological insulators, can play a crucial role in overcoming the challenges associated with terahertz photonic applications. In particular, we have recently used quantum metamaterials, which include a photonic structure to increase light-matter interaction, to demonstrate record-high nonlinear susceptibilities, near-milliwatt generation of third harmonic signal, and THz-induced emission of visible light.

A broadly tunable THz nonlinear QCLs with enhanced conversion efficiency by employing a homogeneous active region is demonstrated. Using an external cavity configuration, the device has achieved tunability from 1.2 THz to 4.5 THz in the operating frequency range. The single dual-upper-state structure with wide gain bandwidth and a high nonlinear susceptibility χ2 enables to realize two-wavelength oscillations without stacking active regions and significantly improves the mid-infrared to THz conversion efficiency, resulting in superior performance over previously reported frequency tunable devices. The device has achieved a conversion efficiency of ~3 mW/W2 around 3.5 THz. In the presentation, spectroscopic measurements using this device will also be reported.

In this talk, we present direct optical injection locking of a 2.5 THz quantum-cascade VECSEL with a 2.5 THz electronic source, namely a diode frequency multiplier chain (FMC). The FMC outputs ~10 µW of power and locks a QC-VECSEL with ~1 mW output power over a ~300 GHz bandwidth. The high-resolution spectral properties of the QC-VECSEL are monitored with a subharmonic diode mixer, and a locked linewidth of ~1 Hz is observed with a signal-to-noise ratio of ~40 dB, in good agreement with the spectral properties of the FMC injected signal.

Chip-scale, electrically-pumped terahertz (THz) quantum cascade lasers (QCLs) can be employed in scattering-type scanning near-field optical microscopy (s-SNOM) to image the response of organic and inorganic materials with nanometer spatial resolution and tomographic sensitivity, overcoming the diffraction limit. By exploiting the self-mixing mechanism, QCLs can work as both sources and detectors, being sensitive to the radiation that is re-injected in the laser cavity after interaction with the tip of the s-SNOM microscope. Interestingly, broadband THz QCL frequency combs (FCs) provide hyperspectral sensitivity to THz s-SNOM systems. The developed technique can be used to perform fundamental investigations at the nanoscale, spanning from inspecting the carrier density distribution in two-dimensional materials, to monitoring the propagation of plasmon–polariton, and phonon–polariton modes with a ~10 nm spatial resolution and over a broad bandwidth. We applied this method to thin films of topological insulators grown by molecular beam epitaxy (MBE), revealing the presence of Dirac surface states by mapping the propagation of surface polaritons.

Spintronic emitters have become important THz sources with broadband emission through ultrafast spin-to-charge conversion. This has recently driven investigations of two-dimensional materials as spintronic THz sources. One such 2D material is the transition-metal dichalcogenide PtSe2. Here we present THz spintronic sources based on high quality epitaxially grown CoFeB/PtSe2/graphene heterostructures, with PtSe2 thicknesses ranging from 1 to 15 monolayers. The unique thickness dependent PtSe2 bandstructure permits to demonstrate different origins of the THz emission - from the inverse Rashba-Edelstein effect in monolayer PtSe2 to the inverse Spin-Hall effect for multilayers. This bandstructure flexibility makes PtSe2 an ideal THz spintronic 2D material.

We have implemented a hyperbolic metamaterial covering a spectral bandwidth of 2000 inverse cm for wavelengths above 4.7 µm. A stack of intercalated heavily-doped InAs and undoped InAs epilayers was grown by molecular beam epitaxy with tellurium as the n-type dopant for obtaining electron concentrations of ~8e19 per cubic cm. The Type II hyperbolicity was determined through the effective optical constants deduced from infrared ellipsometry measurements of the stacks. The materials were then dry etched to form ID gratings with features ranging from 1 to 5 µm. The effective optical constants were used to model the grating’s optical response by finite element electromagnetic calculations. The models showed the formation of hyperbolic plasmon polaritons at the same frequencies where experimental features were observed. This material is based upon work supported by the Office of the Undersecretary of Defense for Research and Engineering Basic Research Office STTR under Contract No. W911NF-21-P-0024. Disclaimer: The content of the information does not necessarily reflect the position or the policy of the Government, and no official endorsement should be inferred.

Optical frequency combs (OFCs) stand as the cornerstone of modern optics, with applications ranging from fundamental science to sensing and spectroscopy. Generation of short optical soliton pulses in passive media such as optical fibers and microresonators has been an established technique for stable OFC formation with a broad optical spectrum – however these platforms are driven by an external optical signal and often rely on additional bulky elements that increase the complexity of the system. Here, we aim to overcome these difficulties by direct OFC generation in mid-infrared semiconductor lasers, such as quantum and interband cascade lasers. After a general introduction to such combs and their nonlinear dynamics, the soliton concept from microresonator Kerr combs will be generalized to active media that are electrically-driven and a new type of solitons in free-running semiconductor laser integrated on a chip will be demonstrated.

Semiconductor quantum dots have emerged as promising nanostructures for efficient single-photon sources and have potential applications in quantum sensing, quantum communications, and quantum computing. In this talk, we review recent advances achieved in the field of quantum dot single-photon sources and explore their capabilities from multiple angles. The talk will begin with an introduction to high temperature operation of quantum dot single photon sources. Overcoming temperature constraints is critical for practical device implementations. The extension of single-photon emission to telecommunication wavelengths will also be discussed, an important milestone for seamless integration with existing optical communication infrastructure. In addition, the integration of quantum dot single-photon sources into silicon photonics circuits will be discussed. The integration of quantum dot technology and silicon photonics will pave the way for complex quantum photonic circuits.

The LINAC Coherent Light Source is a multidisciplinary user facility that provides ultrafast (femtosecond) and ultrashort (attosecond) x-ray pulses to the scientific community. Since first light in 2009, hundreds of impactful science studies have been undertaken in areas including topological insulators, imaging optical phonons, observing energy transfer in photosystem II, high field physics, and attosecond imaging of molecular orbitals. We have recently upgraded our capabilities by increasing the x-ray pulse repetition rate from 120 Hz to 91 kHz and we are currently commissioning a new suite of instruments. These instruments are poised to specifically address emergent phenomena in quantum materials such as superconductivity, magnetics, and ferromagnetism in addition to other key challenges in biology, catalysis and photocatalysis, fundamental dynamics of energy and charge, nanoscale material dynamics, and matter under extreme conditions. In this talk I will discuss the new instrument capabilities of LCLS II and provide some current examples of science we are envisioning.

The silicon vacancy center in 4H-SiC is an optically active defect with spin transitions that can be initialized and read out at room temperature. The sensitivities of room temperature magnetometers using these defects have been limited by decoherence due to a magnetically noisy host crystal. In this work we demonstrate coherence time improvements of silicon vacancy ensembles via isotopic purification of SiC and through a novel choice of basis in the S=3/2 ground state of the defect. Using this, we realize a broadband room temperature magnetometer with a 4nT/rt(hz) sensitivity and a 200pT/rt(Hz) shot noise limited sensitivity.

We are developing sCMOS-based X-ray cameras for time-resolved X-ray spectroscopy, aiming to optimize their capabilities for high-repetition rate imaging and spectroscopy, as well as single photon detection. Prototype development is underway, with a focus on features like reducing image acquisition time, creating a high-density vacuum feedthrough, and achieving homogeneous dark current levels. Collaborative experiments with the Max Born Institute demonstrate the initial success of the camera, and future applications involve studying charge transfer processes and transient absorption of soft X-rays in solution.

In this talk we will review our recent demonstrations of mid-IR lasers grown on (001) Si or Ge substrates (diode lasers, interband cascade lasers, quantum cascade lasers) and compare their performance to those grown on their native substrates. We will demonstrate light coupling from lasers grown on patterned Si photonics wafers to passive SiN waveguides, with a coupling efficiency in line with simulations. Finally, we will discuss and evaluate strategies to enhance the coupling efficiency.

The incorporation of group IIIB elements such as scandium (Sc) and yttrium (Y) can transform conventional III-nitride semiconductors to be ferroelectric. In this talk I will present recent advances of ferroelectric nitride semiconductors, including epitaxy, properties, and emerging device applications. Molecular beam epitaxy of a broad range of ferroelectric nitrides, including ScAlN, ScGaN, YAlN, and their heterostructures and nanostructures, together with their unique piezoelectric, dielectric, ferroelectric, and nonlinear optical properties will be discussed. The realization of ultrathin ferroelectric nitride heterostructures and the underlying physics and properties will be presented, together with their applications in quantum photonics and electronics.

We have developed a novel millimetre-sized monolithic fibre-coupled rubidium saturated absorption spectroscopy laser reference suitable for quantum sensing applications. It is based on our novel MEMs vapour cell technology and bonding of optical elements to create a monolithic spectroscopy module. Our unit reproduces the signal visibility of a 70 mm long cell and is compatible with standard packaging techniques. The unit has no free-space elements that would otherwise be subject to vibration. Our reference uniquely combines the qualities of robustness, miniaturisation and signal strength providing an optimal solution for mobile quantum sensing platforms including space and aerospace.

Optimal quantum control (OQC) enabled by femtosecond laser pulse shaping techniques provides a highly flexible approach to quantum states manipulation in solid-state qubit systems. Here we apply OQC to optimize the form of the triggering laser pulse for a single photon source. The use of a frequency-swept laser pulse possessing a notch resonant with the transition energy of the quantum emitter enables the spectral isolation of the emitted photon stream in conjunction with resonant driving for good indistinguishability. We show that the robustness of this scheme would enable spectral multiplexing of quantum light sources using a single triggering laser pulse.

Colloidal semiconducting nanocrystals (NCs) offer attractive opportunities for optoelectronics. They can self-assemble into solid compact layers and their properties can be adjusted with great flexibility to address frequency windows that are otherwise difficult and/or expensive to cover with standard semiconductors. In this talk, we will discuss the emission and absorption of near-infrared PbS NC assemblies and show that carrier thermalization among neighboring NCs govern their properties (such as the precise Stokes shift between absorption and emission, the shape of the spectra, the wavevector distribution, the carrier recombination rate…). Then we will use this insight to demonstrate unconventional optoelectronic devices in which ensembles of PbS nanocrystals are weakly coupled to tailored photonic environments, such as incoherent sources emitting light with broadband phase and/or polarization singularities. Funding: European Research Council grant FORWARD (reference: 771688).

Interrogating surface phonon polariton (SPhP) modes has mostly been pursued by measuring the far field behavior of resonant modes, through which SPhPs can be investigated by looking at resonant frequencies and linewidths along with the strength of the resonances. In other instances, the study of SPhPs has been accomplished by mapping electromagnetic fields solely at the surface of nanostructured resonators by atomic force microscopy assisted techniques and, in some limited cases, measuring the three-dimensional fields using electron scattering. Accurate knowledge of SPhPs has been hindered by the absence of experimental techniques to map eigenstates in three dimensions that are easy, cheap, and non-destructive. Here, confocal Raman microscopy is used to obtain the spatial distribution of phonon modes in nanostructured polar materials. We demonstrated that SPhPs couple to bulk Raman modes through the material's polarizability and, to a lesser extent, via electron-phonon coupling. These observations provide a new method for measuring SPhP modes in nanostructured materials and a novel way to investigate the physical phenomena involved in coupling bulk phonons to SPhPs.

Nanoresonators enhance many light-matter-interaction processes and are used in various modern applications in nano-quantum optics. They are open systems and their eigenstates are always leaky and have a finite lifetime (complex frequency), even when they are dark states. The consequence of the leakage is that the modal field exponentially growths outside the resonators. This growth is often seen as unphysical. We challenge this opinion.

Orbital angular momentum can be used to tune spatial and spectral components in structured light. Flat optical devices and digital holographic elements can be arranged to establish spatial and temporal correlations and produce structured light beams for advanced photonics applications.

Early detection of a tumor makes it more probable that the patient will, finally, recover. The current approach in diagnosis focuses on microbiological, immunological, and pathological aspects rather than on the “metamaterial geometry” of the diseases. The determination of the effective properties of the biological tissue samples and treating them as disordered media has become possible with the development of effective medium approximation techniques. The obtained effective permittivity values are affected by various factors, like the amount of different cell types in the sample. The identification of the cancer affected areas based on their effective medium properties was performed.

We present a novel optical sensor platform designed for the detection of medical biomarkers. The sensor operates by utilizing reflection variation resulting from the modification of Fano resonance conditions. By fabricating one- and two-dimensional subwavelength quasi-periodic structures made of polymer and coated with an inorganic layer, we enable the functionality of the sensor, ultimately leading to increased sensitivity and detection threshold. The development of the sensor’s platform involves a multi-step process. The detection mechanism primarily relies on the optical response of the biosensor. The presence of analytes induces a spectral shift of the Fano resonance, which is caused by the modification of the biolayer thickness. This optical sensor platform holds significant potential for the detection of a variety of medical biomarkers, including analytes related to various pathogenes, cancer biomarkers, and others.

Liquid metals (LMs) and metal alloys offer an alternative two-dimensional (2D) material synthesis platform as the Cabrera-Mott oxidation reaction occurs at the solid-gas interface once exposed to ambient conditions. As a result, a smooth and ultrathin oxide layer attaching weakly to the LM solvent forms, can be transferred easily onto desired substrates. To date, several LM-based syntheses have been developed and gained popularity since they offer scalable, low-temperature, cost-effective, and vacuum-free alternatives to conventional processes. The liquid metal-based synthesis strategies allow the isolation of centimetre-scale, super-thin nanosheets of 2D metal oxides with high reproducibility. These oxides can then be directly used or processed further into desired compounds like metal nitrides and metal sulfides which also own promising electronic and optical properties. The as-synthesized 2D nanosheets are subsequently fabricated as basic electronic, optoelectronic, and sensing devices exhibiting remarkable performances. The findings are expected to inspire significant further work in the field of ultra-thin transparent and flexible electronics.

Optically active defects in wide band-gap semiconductors are a leading candidate for use as ultra high-sensitivity quantum sensors of strain as well as electric and magnetic fields. The availability of large size substrates, mature epitaxial growth and fabrication techniques, and excellent optical and electrical properties make silicon carbide (SiC) attractive, in comparison to diamond, for fully integrated and electrically controllable quantum magnetometers. We present high brightness and sensitivity of ensemble surface proximal defects deterministically generated within porous silicon carbide produced by a damage-free metal-assisted chemical etching method.

Excitonic optical processes in layered and atomically thin semiconductors find important applications in advanced optoelectronic and quantum devices. In this talk, we discuss the development and application of first-principles computational methods to investigate exciton-phonon interactions in atomically thin nitride semiconductors. We focus on atomically thin GaN quantum wells as a means to produce stable excitons at room temperature in a commercial material platform. We demonstrate that the reduced dimensionality increases the exciton binding energy by approximately an order of magnitude, enabling stable excitons at room temperature. Moreover, we investigate excitons and exciton-phonon interactions in bulk and monolayer hexagonal BN. We demonstrate that, despite its indirect gap, hexagonal BN exhibits bright phonon-assisted luminescence at room temperature for efficient excitonic UV light emitters. Our theoretical insights on exciton-phonon interactions and their impact on exciton recombination times aim to guide the design and development of atomically thin semiconductor-based optoelectronic and quantum devices with increased efficiency at room temperature.

Magneto-plasmonic resonant structures, which combine magnetic and metallic materials, are well known for improving biosensing and magnetic field detection. However, these structures suffer from low optical quality resonances (reflection dip) caused by the high absorption of plasmonic oscillations, which limits their practical applications. This paper proposes low-loss optical planar structures that may hold great promise for sensing applications. The first ones are unconventional magneto-plasmonic devices optimized for a so-called configuration “optical switch” [1]. The structure consists of a 1D deep sinusoidal gold grating covered by a thin cobalt layer. The second ones are all-dielectric devices made of a magneto-optical nanocomposite layer with a 1D photoresist grating on top [2]. Such magneto-optical devices are easy to implement and cost-effective, providing a very promising approach for magnetic field sensors, or biosensing in a both directions magnetized biased configuration. [1] A. V. Tishchenko and O. Parriaux, doi: 10.1109/JPHOT.2015.2445766. [2] Laure Bsawmaii et al. doi : https://doi.org/10.1364/OME.447030

Optical-frequency combs are versatile tools for measuring time, transmitting data, identifying chemicals, sensing distance, and supporting quantum-information science. A new direction is to produce frequency combs through intriguing nonlinear behaviors of light in integrated microresonators. I will discuss experiments with Kerr microresonators that explore exotic regimes of soliton dynamics and applications of these soliton combs.

Interlayer excitons (IXs) in transition metal dichalcogenides are promising for applications in opto-electronics and quantum technologies. They have strongly tunable energy through external electric fields and can be confined to specific moiré sites, which are adjustable through twist angles. IX emission exhibits a strong blueshift with optical pumping densities which has been correlated to exciton-exciton interaction [1]. By directly imaging the IX with time-resolved angle-resolved photoemission spectroscopy (trARPES), we can attribute a IX blueshift to a change in the band alignment created from the charge transfer associated with IX. This study complements optical studies and informs our understanding of IX-IX interactions. [1] Nagler, P., et al. 2D Materials 4, 2, 025112 (2017).

Moiré heterostructures of layered materials such as transition metal dichalcogenides enable periodic arrays of localized quasi-particles with long-range Coulomb interactions which can host a plethora of quantum phenomena. Depending on the lattice mismatch and twist angle across the individual layers, resulting moiré potential modulates the distribution of electronic states, significantly changing the landscape of moiré excitons and their characteristics. We employ simultaneous hyperspectral electron energy loss spectroscopy and annular dark field imaging in a scanning transmission electron microscope to investigate WS2/WSe2 heterostructures at the nanoscale. Through this technique, we present the mapping of intralayer moiré excitons within a moiré supercell, shedding light on the interplay between interlayer coupling and atomic reconstruction. Our observations provide valuable insights into the mechanisms governing the formation and confinement of moiré excitons in these systems.

Monolithic subwavelength gratings integrated with metal (metalMHCG) enable nearly total transmission of light and can be fabricated with common semiconductor materials, however, they require a very high-aspect ratio between height and period of the metalMHCG stripes which is technologically challenging. This study aims the optimization of metalMHCG fabrication procedure by plasma etching taking into account the influence of process gas flow, their composition, pressure, power, and temperature on the wall shape of metaMHCG, etch rate, and etch selectivity. In the result, metalMHCG with high-aspect ratio and dimensions enabling nearly total transmission are fabricated.

Nanomaterial-enabled optoelectronic and sensing devices offer extraordinary advantages through their unique properties and functionalities. However, their performance levels are usually inadequate to meet the stringent demand for practical applications. An increasingly popular strategy to address these challenges is through the exploitation of computational algorithms in such devices. I will give specific examples of how nanomaterial-based devices could benefit from such approaches as the key enabler. The first example will be through the development of an ultraminiaturised computational spectrometer from a single nanostructure without complex optics or filters. I will then briefly discuss how the philosophy of mathematically combining the output of seemingly unconnected devices could be applied to more sophisticated designs, where active modulation of optoelectronic properties in a single device structure can enable even more miniaturised systems, representing a future application-agnostic platform with unmatched simplicity and compactness.

Atomic vapor cells are an important component of many quantum experiments, and MEMS fabrication techniques allow for miniaturization of vapor cells and their associated experiments. Anodic bonding is the most popular technique for this cell fabrication, but it is limited to simple glass-to-silicon bonding interfaces. Here we present fabrication of a MEMS vapor cell using a stack that includes PIC-compatible thin-film borosilicate glass as a bonding surface. We anodically bond a deposited thin film of borosilicate glass to a patterned silicon frame during our fabrication of a MEMS rubidium vapor cell. This technique will allow for wider integration of MEMS vapor cells to photonic integrated circuits.

Intensity, polarization, wavelength are intrinsic dimensions of light and can carry important information enabling a plethora of useful applications in optical communication, remote sensing, chemical and biological characterization. I will show our recent progress in multidimensional light and thermal field processing with non-local optics.