Applications In Photonic Devices Research Articles

Eu3+-doped ZnO quantum dots: structure, vibration characteristics, optical properties, and energy transfer process.

This article studies the synthesis, as well as the structural, vibrational, and optical properties of Eu3+-doped ZnO quantum dots (QDs) and investigates the energy transfer mechanism from the ZnO host to Eu3+ ions using Reisfeld's approximation. Eu3+-doped ZnO QDs at varying concentrations (0-7%) were successfully prepared using a wet chemical method. The successful doping of Eu3+ ions into the ZnO host lattice, as well as the composition and valence states of the elements present in the sample, were confirmed through X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses. XRD results demonstrated the crystalline nature of the ZnO QDs, revealing their wurtzite (WZ) structure with no secondary phases. XPS analysis provided further confirmation of the presence of Eu3+ ions within the ZnO host, with clear signals corresponding to the Zn, O, and Eu elements. The valence states of Eu were verified as trivalent (Eu3+), confirming the successful doping of Eu3+ ions, as evidenced by the characteristic Eu 3d peaks in the XPS spectra. Raman spectroscopy (RS) was employed to analyze the vibrational modes, revealing shifts in ZnO lattice vibrations due to Eu3+ incorporation, indicating strong coupling between Eu3+ ions and the ZnO host. Optical properties were studied using UV-Vis absorption, photoluminescence (PL) spectroscopy, and PL decay spectroscopy, showing a significant enhancement of red emission, attributed to the 5D0 → 7F2 transition of Eu3+ ions under UV excitation. Using Judd-Ofelt (JO) analysis, the intensity parameters (Ω 2, Ω 4, Ω 6) were derived, providing insights into the asymmetry of the Eu3+ ion's local environment and the radiative transition probabilities. Energy transfer processes between the ZnO host and Eu3+ dopants were examined, showing efficient sensitization of Eu3+ through excitation of the ZnO host, with an optimal Eu3+ doping level maximizing luminescence. Eu3+-doped ZnO QDs, which emit in the visible light region and are non-toxic, have great potential for applications in photonic devices, light-emitting diodes, and bioimaging.

Tailoring second harmonic generation in a multilayer WS2 flake via a silicon circular Bragg grating.

Nonlinear emission phenomena observed in transition metal dichalcogenides (TMDCs) have significantly advanced the development of robust nonlinear optical sources within two-dimensional materials. However, the intrinsic emission characteristics of TMDCs are inherently dependent on the specific material, which constrains their tunability for practical applications. In this study, we propose a strategy for the selective enhancement and modification of second-harmonic generation (SHG) emission in a multilayer WS2 flake through the implementation of a silicon (Si)-based circular Bragg grating (CBG) structure positioned on an Au/SiO2 substrate. By selectively exciting the region of the circular Bragg grating with the grating oriented either parallel or perpendicular to the linearly polarized pump beam, we successfully achieved wavelength-tunable SHG intensity peaks at 402.5 nm and 425 nm for the respective alignments. Our experimental findings, corroborated by numerical simulations, indicate that the enhancement of SHG intensity is highly sensitive to the orientation of the grating region of the CBG. Power-dependent SHG spectra further validate the quadratic dependence of SHG, while comparative analysis with WS2 flakes on a bare Si/Au/SiO2 substrate highlights the critical role of the CBG structure in modulating SHG. This research underscores the potential of CBG-augmented TMDCs for the control of nonlinear optical emissions, suggesting promising applications in photonic devices and selective emission technologies.

On the Optical response of all-dielectric metasurface in the exceptional point

All-dielectric nanophotonics leverages high-refractive-index dielectric materials to manipulate light at the nanoscale with minimal energy loss, offering strong electric and magnetic resonances. These properties make all-dielectric structures ideal for a range of advanced photonic applications, from ultra-thin lenses to sensors. In this study, we explore the multipole response of all-dielectric metasurfaces when operating near an exceptional point (EP), a singularity in non-Hermitian systems where eigenmodes coalesce. Numerical simulations reveal that at the EP, the metasurface’s resonance splits, with significant contributions from magnetic dipole (MD) and electric quadrupole (EQ) modes. These findings enhance our understanding of EPs in metasurface physics and highlight the potential of this geometry for applications in photonic devices.

Flexible Photonic Materials and Devices: Synthetic Strategies, Sensing Properties, and Wearable Applications

AbstractWearable technology is becoming increasingly visible in the daily life for improving human health and performance. Flexible photonics is rapidly emerging as a promising platform for advancing the wearable technology. The development and innovative use of flexible photonic materials play crucial roles in designing flexible sensor devices for wearable applications. Here it is aimed to summarize the key advancements in developing flexible photonic materials and devices for wearable sensing applications. In turn the synthetic strategies, sensing properties, and wearable applications of flexible photonic materials and devices will be comprehensively discussed. Finally, it is attempted to give an outlook on the future challenges and research trends in this fascinating field.

Symmetry-protected and Brillouin zone folding driven bound states in the continuum in dielectric nanorod arrays for effcient third harmonic generation

Abstract Two types of bound states in continuum (BICs), symmetry-protected and Brillouin zone folding driven, are identified in the hollow Si nanorod arrays. By modulating the direction and distance of the air holes from the center of the nanorods, it is possible to achieve either a single quasi-BIC or three quasi-BICs. The transmission spectra exhibit ultra-narrow lines, and the quasi-BICs demonstrate ultra-high Q factors. Additionally, effcient third-harmonic generation occurs at low pump intensities. The results indicate that the proposed nanostructures of two types of BICs with a flexible modulation hold great potential applications for nonlinear photonic devices.

Dual-function switchable terahertz surface plasmon device driven by a GST metasurface

Surface plasmons (SPs) are one of the most effective information carriers for on-chip systems due to their two-dimensional propagation properties. Benefitting from the highly flexible designability, metasurfaces have emerged as a promising route in realizing SP devices. However, related studies are mainly focused on passive devices. Here, by introducing nonvolatile phase-change material Ge2Sb2Te5 (GST) into the metasurface design, we experimentally demonstrate a dual-function switchable SP device in the terahertz regime. Specifically, the device works as a spin-dependent directional plane-wave SP coupler when GST is in the amorphous state, while it works as a spin-dependent directional SP Fresnel zone plate (FZP) when GST is in the crystalline state. The states of GST are switched back and forth using thermal excitation and nanosecond laser illumination, respectively. Our method is simple and robust, and can find broad applications in on-chip photonic devices.

Analysis of Optical Thin-films: Towards Lower Reflectivity for High Performance Solar Cells and Modern Photonic Devices Applications

Recently, optical thin-films with lower reflectivity have attracted much interest for their suitability in high performance thin-film solar cells and various modern photonics devices, such as electronic display panels touchscreens, smart optical glass windows, spectacles frames, super-compact camera lenses, laser systems and optical fiber communications since lowering reflectivity coating improves the device performances. However, obtaining reduced reflectance from this arrangement remains challenging issue. As the film optical properties, such as the absorbance, reflection and transmission of particular wavelength of electromagnetic radiation can be carefully controlled by optimizing thin-film fabrication materials as well as structures, there is a lot of research scope in optimizing device reflectivity by assessing various film- and substrate materials as well as their thicknesses. Therefore, in this study, the reflectance performances of optical thin-films were characterized for obtaining lower reflectivity for various types of modern photonics applications. To obtain this, three novel optoelectronic materials InGaAs, CdTe and CsPbBr<sub>3</sub> for film layer<sub>, </sub>three widely used substrate materials glass, Al<sub>2</sub>O<sub>3 </sub>and steel as well as various thicknesses of film layer were evaluated. Reflectance studied of the thin-films for the three film materials have been clarified that CsPbBr<sub>3 </sub>is the best among these three film materials to be used for reducing the light reflection of the thin-film. Lower reflectivity of thin-films on glass substrate suggested that glass is better than both Al<sub>2</sub>O<sub>3 </sub>and steel as substrate in high efficiency thin-film solar cells and various photonics devices. In addition, evaluation of reflectance for various film thicknesses showed that ultra-thin film layer is superior for reducing the reflection of solar energy by thin-film structure. We have therefore proposed that thin-film with the combination of CsPbBr<sub>3</sub> based ultra-thin film layer on glass substrate would be one of the best possible solutions for reducing reflectivity of solar cells and various photonics devices, thereby for possibly increasing the performance efficiency. This research result would be very beneficial for the development of renewable energy and photonics based nanotechnology, thereby play a significant role for reducing global energy crisis and green-house gas emission concurrently and sustainably in the modern world.

Efficient synthesis of fluorinated triphenylenes with enhanced arene–perfluoroarene interactions in columnar mesophases

The high potential of non-covalent arene–fluoroarene intermolecular interactions in the design of liquid crystals lies in their ability to strongly promote self-assembly, improve the order and stability of the supramolecular mesophases, and enable tuneability of the optical and electronic properties, which can potentially be exploited for advanced applications in display technologies, photonic devices, sensors, and organic electronics. We recently successfully reported the straightforward synthesis of several mesogens containing four lateral aliphatic chains and derived from the classical triphenylene core self-assembling in columnar mesophases based on this paradigm. These mesogenic compounds were simply obtained in good yields by the nucleophilic substitution (SNFAr) of various types of commercially available fluoroarenes with the electrophilic organolithium derivatives 2,2'-dilithio-4,4',5,5'-tetraalkoxy-1,1'-biphenyl (2Li-BPn). In a continuation of this study, aiming at testing the limits of the reaction and providing a large diversity of structures, a structurally related series of compounds is reported here, namely 1,2,4-trifluoro-6,7,10,11-tetraalkoxy-3-(perfluorophenyl)triphenylenes (Fn). They were obtained by reacting the above mentioned 2,2’-dilithiobiphenyl derivatives with decafluorobiphenyl, C6F5–C6F5. These compounds differ from the previously reported series, 1,2,4-trifluoro-6,7,10,11-tetraalkoxy-3-aryltriphenylenes (PHn), solely by the substitution of the terminal phenyl ring with a pentafluorophenyl ring. Thus, as expected, they display a Colhex mesophase over large temperature ranges, with only small differences in the mesophase stability and transition temperatures. Furthermore, the presence of the terminal fluorophenyl group enables a subsequent second annulation, yielding a new series of extended polyaromatic mesomorphic compounds, i.e., 1,1',3,3',4,4'-hexafluoro-6,6',7,7',10,10',11,11'-octaalkoxy-2,2'-bitriphenylene (Gnm) which were found to display a Colrec mesophase. The specific nucleophilic substitution patterns of the Fn derivatives and the antiparallel stacking mode into columnar structures stabilized by arene–perfluoroarene intermolecular interactions were confirmed by the single-crystal structure of the alkoxy-free side chain analog, i.e., 1,2,4-trifluoro-3-(perfluorophenyl)triphenylene (F). UV–vis absorption and fluorescence emission spectroscopies reveal green photoluminescence with fluorescence quantum yields of up to 33% for the Fn derivatives. The J-aggregation for the inner fluorine-substituted dimers Gnm is energetically and stereoelectronically more favorable and G66 exhibits thin-film fluorescence with a large red-shift of the emission peak.

Unraveling the structure-property relationship of novel thiophene and furan-fused cyclopentadienyl chromophores for nonlinear optical applications.

Development of organic nonlinear optical materials has become progressively more important due to their emerging applications in new-generation photonic devices. A novel series of chromophores based on innovative thiophene and furan-fused cyclopentadienyl bridge with various powerful donor and acceptor moieties were designed and theoretically investigated for applications in nonlinear optics. To unravel the structure-property relationship between this new push-pull conjugated systems and their nonlinear optical property, multiple methods, including density of states analysis, coupled perturbed Kohn-Sham (CPKS) method, sum-over-states (SOS) model, the two-level model (TSM), hyperpolarizability density analysis, and the (hyper)polarizability contribution decomposition, were performed to comprehensively investigated the nonlinear optical and electronic properties of this new π-system. Due to excellent charge transfer ability of new bridge and distinctive structure of donor and acceptor, the designed chromophores exhibit deep HOMO levels, low excitation energy, high dipole moment difference and large hyperpolarizability, indicating the appealing air-stable property and remarkable electrooptic performance of them. Importantly, THQ-CS-A3 and PA-CS-A3 shows outstanding NLO response properties with βtot value of 6953.9 × 10-30 and 5066.0 × 10-30 esu in AN, respectively. The influence of the push-pull strength, the heterocycle and the π-conjugation of new bridge on the nonlinear optical properties of this novel powerful systems are clarified. This new series of chromophores exhibit remarkable electro-optical Pockels and optical rectification effect. More interestingly, PA-CS-A3 and THQ-CS-A2 also show appealing SHG effect. This study will help people understand the nature of nonlinear optical properties of innovative heteroarene-fused based cyclopentadienyl chromophores and offer guidance for the rational design of chromophores with outstanding electrooptic (EO) performance in the future.

Enhancement of third-order optical nonlinearity in effective epsilon-near-zero metamaterials of dielectric/metal/dielectric sandwich nanostructures

We report the enhancement of third-order optical nonlinearity in dielectric/metal/dielectric sandwiches driven by the epsilon-near-zero (ENZ) effect. The lithium niobate (LN) and Au are chosen as the typical dielectric and metal, respectively. The sandwich nanostructure consists of two layers of LN film (90 nm) and an insertion of Au layer of different thicknesses (9, 13, and 17 nm). The ENZ wavelength of LN/Au/LN (LAL) sandwiches is experimentally obtained with a modulation from 0.96 μm (Au layer 17 nm) to 1.33 μm (Au layer 9 nm). The nonlinear refractive index n2 and nonlinear absorption coefficient β are determined at variable near infrared wavelengths using the Z-scan method. The maximum n2=2.31×10−14(6.76×10−15)m2/W and β=−9.20×10−8(−1.94×10−8)m/W are obtained in the LAL sandwich with a 13 nm Au layer of ENZ wavelength 1.088 μm at the wavelength 1.064 μm with a pulse duration of 25 ps (120 fs). The n2 is around 19 and 25 times larger than those in the pure LN film of thickness 180 nm measured at the picosecond and femtosecond time domains, respectively. The enhancement of n2 in LAL sandwiches follows the numerical results obtained from the ENZ effect. Especially, the LN layer and the Au layer have comparable contributions to the effective third-order susceptibility χeff(3), which leads to the reconfigurable χeff(3) by changing the thickness of each layer and further to modulate the n2 and β of the samples. The results offer a promising way to attain large and reconfigurable optical nonlinearities for application in all-optical photonic devices at a specified wavelength.

Efficient supercontinuum spectra by non-Gaussian pulses

Abstract In this article, we examine the generation of supercontinuum spectra using various non-Gaussian pulses in semiconductor quantum wells. Specifically, we employ weak probe pulses modulated by a strong optical beam, leveraging electromagnetically induced transparency within the system. Our findings indicate that the characteristics of supercontinuum generation, as compared to traditional Gaussian pulses, differ significantly when non-Gaussian pulses, such as sinh-Gaussian, cosh-Gaussian, and tanh-Gaussian pulses are being used. Notably, among the pulses studied, the cosh-Gaussian pulse achieves the broadest supercontinuum span, reaching ~21 μm, at the end of the semiconductor quantum well. These results suggest potential applications in optoelectronic and photonic devices designed for spectroscopic analysis.

Photocurrent in PZT/TiOx composite film prepared via self-assembly of perovskite matrix and ALD of titania

A novel approach for the preparation of ferroelectric composite films has been successfully developed by combining sol–gel evaporation-induced self-assembly (EISA) of porous lead zirconate titanate (PZT) films with atomic layer deposition (ALD) of titania. The EISA process, which utilizes a Brij-type surfactant, facilitates the formation of large columnar perovskite grains with narrow (∼20 nm) interconnected pores. ALD, employing the thermal reaction of titanium isopropoxide with water, ensures uniform titania growth within the pores throughout the film thickness, as demonstrated by transmission electron microscopy and ellipsometric porosimetry. The resulting PZT-TiOx composite films exhibit a pronounced photovoltaic current under visible light illumination, attributed to electron excitation from the valence band to Ti3+ states, followed by movement via a hopping conduction mechanism. The photocurrent value varies with the direction of polarization. This behavior presents a potential method for controlling photoconductivity through polarization, with possible applications in electronic and photonic devices.

Is There an Optimal Spacer Cation for Two-Dimensional Lead Iodide Perovskites?

Two-dimensional lead iodide perovskites have attracted significant attention for their potential applications in optoelectronic and photonic devices due to their tunable excitonic properties. The choice of organic spacer cations significantly influences the light emission and exciton transport properties of these materials, which are vital for their device performance. In this Perspective, we discuss the impact of spacer cations on lattice dynamics and exciton-phonon coupling, focusing on three representative 2D lead iodide perovskites that exhibit distinct types of structural distortions. Minimizing structural distortions, such as dynamic out-of-plane octahedral tilting and lone pair distortion, appears to be essential for achieving narrow photoluminescence (PL) emission peaks, high PL quantum yields, and rapid exciton diffusion by suppressing exciton-phonon coupling, as demonstrated in 2D perovskites based on phenylethylammonium cation or its derivatives. We propose that designing spacer cations with enhanced intermolecular interactions and denser packing, combined with the close packing of inorganic ions to minimize the motions of both organic and inorganic lattices, would be the ideal scenario for yielding the most favorable optoelectronic properties in these materials.

Excitonic-Vibrational Interaction at 2D Material/Organic Molecule Interfaces Studied by Time-Resolved Sum Frequency Generation.

The hybrid heterostructures formed between two-dimensional (2D) materials and organic molecules have gained great interest for their potential applications in advanced photonic and optoelectronic devices, such as solar cells and biosensors. Characterizing the interfacial structure and dynamic properties at the molecular level is essential for realizing such applications. Here, we report a time-resolved sum-frequency generation (TR-SFG) approach to investigate the hybrid structure of polymethyl methacrylate (PMMA) molecules and 2D transition metal dichalcogenides (TMDCs). By utilizing both infrared and visible light, TR-SFG can provide surface-specific information about both molecular vibrations and electronic transitions simultaneously. Our setup employed a Bragg grating for generating both a narrowband probe and an ultrafast pump pulse, along with a synchronized beam chopper and Galvo mirror combination for real-time spectral normalization, which can be readily incorporated into standard SFG setups. Applying this technique to the TMDC/PMMA interfaces yielded structural information regarding PMMA side chains and dynamic responses of both PMMA vibrational modes and TMDC excitonic transitions. We further observed a prominent enhancement effect of the PMMA vibrational SF amplitude for about 10 times upon the resonance with TMDC excitonic transition. These findings lay a foundation for further investigation into interactions at the 2D material/organic molecule interfaces.

(Invited) Nanoscale Ferroelectric Nitrides for Next Generation Electronics and Quantum Photonics

The incorporation of rare earth elements such as scandium (Sc) can transform conventional III-nitride semiconductors to be ferroelectric. This new class of ferroelectric nitride semiconductors can be seamlessly integrated with the well-established III-nitride and Si electronics with promising applications in memory and logic devices as well as high power, high frequency, and high temperature electronics. Moreover, ferroelectric nitrides exhibit significantly enhanced piezoelectric and nonlinear optical response compared to AlN, which makes it attractive for high frequency resonators and filters and nonlinear optical processes. In this talk I will present recent advances of nanoscale ferroelectric III-nitride semiconductors, including molecular beam epitaxy, structural, optical, electrical, and ferroelectric properties, as well as their emerging electronic and photonic device applications.

Polarization-independent topological corner states based on all-dielectric valley photonic crystals

Recently, topological edge states and corner states have provided new ways to manipulate light transmission and localization. Up to now, most works have focused on either transverse magnetic or transverse electric polarization. In contrast, dual-polarization photonic topological states have attracted extensive attention because of their potential applications in polarization-independent photonic devices. Previous study realizes the polarization-independent topological corner states by independently tuning the out-of-plane permittivity and the in-plane permittivity of the anisotropic elliptic metamaterial, which is difficult to realize in the optical regime. In this work, we achieve polarization-independent topological edge states and corner states based on all-dielectric fishnet photonic crystals made of isotropic material. Note that the frequencies of the topological edge states and corner states depend on the structure’s effective refractive index, which is related to the filling ratio of the dielectric material. By selecting a suitable filling ratio of the dielectric material, polarization-independent edge states and corner states are realized. In addition, we further construct a topological waveguide-cavity coupling system and demonstrate the function of a polarization-independent optical notch filter. Our work paves the way for the implementation of polarization-independent topological photonic devices.

Photonic modes in twisted graphene nanoribbons

This study investigates the behavior of photonic modes in twisted graphene nanoribbons (TGNRs) using an analytical approach based on solving the fully covariant vector boson equation. We present a model that demonstrates how helical twisting in TGNRs significantly affects the evolution of photonic modes. Our analytical solutions yield detailed expressions for mode profiles, energy spectra, and decay characteristics. We find that increasing the twist parameter shortens the decay times (τns) for damped modes, indicating enhanced photonic coupling due to the twisted geometry. Conversely, longer nanoribbons (NRs) exhibit increased decay times, showing a length (L)-dependent effect, where τns∝L/c, with c representing the speed of light. These findings may enhance the understanding of light control in nanostructures and suggest potential applications in tunable photonic devices, topological photonics, and quantum optical systems.

Excitonic Effects on the Ultrafast Nonlinear Optical Response of MoS2 and Fluorinated Graphene/MoS2 Heterostructure Films for Photonic Applications.

In the present work, the ultrafast nonlinear optical (NLO) response of some molybdenum disulfide (MoS2), fluorinated graphene (FG), and FG/MoS2 heterostructure thin films was studied using the Z-scan and optical Kerr effect techniques employing femtosecond laser pulses at different excitation wavelengths (i.e., 400, 570, 610, 660, 800, and 1200 nm). The experiments have shown that the NLO response of the MoS2 and MoS2/FG films was significantly enhanced when the films were excited with 400, 610, and 660 nm laser pulses due to resonance effects with the close-lying excitons in these nanostructures. For a better evaluation of the resonant enhancement of the NLO response, measurements were also carried out at off-resonant wavelengths, i.e., at 570, 800, and 1200 nm. The presence of excitons in the MoS2 and MoS2/FG films resulted in strong saturable absorption and self-defocusing, with exceptionally large values of third-order susceptibilities χ(3) ranging from 10-12 to 10-13 esu. In addition, the NLO response of the MoS2/FG heterostructure was found to be stronger than that of the individual MoS2 and FG films, most probably attributed to interlayer carrier transfer. The determined NLO parameters of the studied nanostructures were found to be comparable to, and in some cases exceeded, those of other reported 2D materials known to exhibit a strong NLO response as well. These findings not only advance the fundamental understanding of the contributions of excitons on the NLO response/properties of transition metal dichalcogenide-based ultrathin films but also highlight the importance of excitons for tailoring their NLO response in view of various applications in advanced optoelectronics and photonic devices.

Enhanced surface emission of bismuth-ion doped glass by adding metal nanoparticles

Enhancing the luminescent properties of doped silica glass has garnered significant interest due to its potential applications in photonics and optoelectronics. In this study, we enhance the surface emission of bismuth(Bi)-doped silica glass by incorporating metal nanoparticles. Utilizing finite-difference time-domain (FDTD) simulations, we observed a significant increase in surface emission following population inversion. We developed a novel algorithm to achieve a uniform distribution of nanoparticles in a two-dimensional computational model, ensuring that the distribution is physically accurate. Through systematic investigation, we explored the effects of the number, distribution, and size of silver nanoparticles on the surface emission enhancement of Bi-doped glass. Our results demonstrate that under optimal conditions, the surface emission enhancement can reach nearly 72%. Additionally, we evaluated the impact of various metal nanoparticles, finding that gold, silver, copper, and platinum positively influence surface emission enhancement, while titanium has an inhibitory effect. This study underscores the potential of metal nanoparticles to significantly improve the luminescent properties of doped glass, paving the way for advanced applications in photonic devices.

Uncovering upconversion photoluminescence in layered PbI2 above room temperature.

As a van der Waals (vdW) layered semiconductor material, lead iodide (PbI2) possessing a direct bandgap with strong photoluminescence emission in visible range has gained wide attention in applications of photonic and optoelectronic devices. Here, upconversion photoluminescence (UPL) in exfoliated PbI2 flakes is demonstrated at room temperature and elevated temperatures. The linear power dependence of UPL emission with 532nm excitation suggests the one-photon involved multiphonon-assisted UPL emission process, which is revealed by the temperature-dependent UPL emission measurement. Meanwhile, the nonlinear power dependence of UPL emission with 561nm excitation indicates the transition of UPL emission mechanism from linear to nonlinear regime, and the temperature-dependent UPL emission study further shows that the upconversion is contributed by both the multiphonon-assisted UPL process and the two-photon absorption induced PL process. This study will provide an insight to the understanding of photon upconversion in vdW layered semiconductors and advancing applications in temperature-controlled photon upconversion, tunable photonics, photodetection and imaging.