Electro-optical Coupling Research Articles

Microstructure and composition driven ferroelectric properties of Er3+ doped lead-free multifunctional 0.94Bi0.5Na0.5TiO3-0.06BaTiO3 ceramics

The x mol Er3+ doped 0.94Bi0.5Na0.5TiO3-0.06BaTiO3 (BNT-BT:xEr3+) ceramics were prepared and their microstructure, electric and luminescent properties were systematically investigated. The microstructure, electric and photoluminescent properties of BNT-BT:xEr3+ ceramics are strongly dependent on the Er3+ composition. The crystal parameters and grain sizes of BNT-BT ceramics strongly depend on Er3+ composition due to the different replacement positions of Er3+ with the increase of Er3+ composition. The ferroelectric and dielectric properties are firstly enhanced due to the decrease of crystal defects, and then suppressed because of the decrease of grain size and the phase transition from R3c to P4bm phase with the increase of Er3+ composition. The discharge energy storage density is improved with a relative change of 67.58% for BNT-BT:1.0%Er3+ ceramics. Furthermore, the depolarization temperature Td and the relaxor antiferroelectric temperature TRE are decreased with the increase of Er3+ composition. But the Curie temperature Tm is enhanced for x< 0.6% as the A-site doping limits the transition from ferroelectric to paraelectric phase. The BNT-BT:xEr3+ ceramics exhibit a strong green emission at 548 nm under the excitation of 487 nm light. The investigation provides a new opportunity in exploring electro-optical coupling materials.

Coherent optical control of a superconducting microwave cavity via electro-optical dynamical back-action

Recent quantum technologies have established precise quantum control of various microscopic systems using electromagnetic waves. Interfaces based on cryogenic cavity electro-optic systems are particularly promising, due to the direct interaction between microwave and optical fields in the quantum regime. Quantum optical control of superconducting microwave circuits has been precluded so far due to the weak electro-optical coupling as well as quasi-particles induced by the pump laser. Here we report the coherent control of a superconducting microwave cavity using laser pulses in a multimode electro-optical device at millikelvin temperature with near-unity cooperativity. Both the stationary and instantaneous responses of the microwave and optical modes comply with the coherent electro-optical interaction, and reveal only minuscule amount of excess back-action with an unanticipated time delay. Our demonstration enables wide ranges of applications beyond quantum transductions, from squeezing and quantum non-demolition measurements of microwave fields, to entanglement generation and hybrid quantum networks.

Electro-Optical Coupling in Double Diode Structures

Alternative types of artificial cooling techniques are of large interest for multiple applications. Here, we develop a framework for studying the role of electro-optical coupling in the analysis of solid-state refrigerators based on electroluminescent cooling (ELC) by combining device measurements with optical simulations. The studied device consists of a light-emitting diode (LED) epitaxially connected to a photodetector (PD) in a double-diode structure (DDS). Previous results of the DDS have indicated that the LED side already operates at conditions corresponding to ELC, but Ohmic losses and imperfect photodetection of the LED light in the PD have prevented observing the effect directly. Here, to break down the detection losses of the DDS, we report on the electro-optical response of the LED and the PD in detail, as well as the role of the spectral coupling from the LED to the PD. We present a detailed framework for combining measurements and simulations of the DDS to gain quantitative insight of the electro-optical response of the LED and PD, as well as the coupling between them, including the analysis of effects that are not directly accessible by standard measurements. The developed approach allows identifying the different photodetection loss mechanisms from the current-voltage and electroluminescence measurements and thereby gives guidance for designs toward a direct demonstration of ELC at practically relevant cooling powers. Somewhat surprisingly, the results show that an imperfect spectral absorption efficiency of the PD, in addition to its below unity quantum efficiency, are together required to explain the previously observed low photodetection efficiency of the DDS even for several microns thick PD structures. In comparison, the LED top mirror introduces only a minuscule drop in photodetection efficiency. Put in plain numbers, our analysis reveals that in the current DDS designs, there is headroom by 14% in the spectral matching between the LED and the PD, 5% in the charge collection efficiency of the PD, and 4% in the efficiency at which photons emitted from the LED reach the PD.

Orbital-Angular-Momentum Quantum State Transformation Via a Nonlinear Process

Orbital-angular-momentum- (OAM) based photonic nonlinear interfaces, such as the nonlinear manipulation of a single-photon OAM state between the communication wavelength for entanglement distribution and the near-visible wavelength for quantum memories. Here, we experimentally demonstrate this kind of quantum state transformation for simultaneously adjusting the weight of the spatial OAM modes and operating the wavelength of single photons by effectively cascading the frequency conversion and electro-optical (EO) polarization coupling in a periodically poled lithium niobate crystal. The fidelity of the OAM state is measured to be higher than 95% before and after the frequency conversion. The results show that the OAM state of single photons can be modulated on demand by applying a transverse electric field across the nonlinear crystal. Our work demonstrates the integration and high performance of our proposed transformation interface, and paves a route toward connecting different remote nodes based on quantum memories in a large-scale OAM-encoded quantum network.

Electromechanical properties and photoluminescence of Er3+-doped PMN-33PT single crystal

Based on the successful growth of large-sized Er3+-doped PMN-PT single crystal, the phase composition, electromechanical properties and photoluminescence of [001]C-oriented Er3+-doped PMN-33PT crystal were investigated in detail. The results show that the crystal coexists in rhombohedral and monoclinic phases at room temperature. The crystal possesses excellent piezoelectric (d33 ∼ 2103 pC/N), dielectric (ε33T ∼ 7589), and electromechanical coupling properties (k33 ∼ 0.91), accompanied by a higher phase transition temperature and larger coercive field compared with that of PMN-33PT single crystal. This indicates an improved electromechanical performance induced by Er3+ doping. Additionally, the crystal achieves upconversion and downconversion luminescence, and a strong dependence of the upconversion emission on temperature is demonstrated. Furthermore, a comparable optical temperature sensing performance based on the fluorescence intensity ratio of the upconversion luminescence is verified. These results demonstrate a promising multifunctional material. The electro-optical coupling performance of the Er3+-doped PMN-33PT crystal is under evaluation.

On-Glass Integrated SU-8 Waveguide and Amorphous Silicon Photosensor for On-Chip Detection of Biomolecules: Feasibility Study on Hemoglobin Sensing

An optoelectronic, integrated system-on-glass for on-chip detection of biomolecules is here presented. The system’s working principle is based on the interaction, detected by a hydrogenated amorphous silicon photosensor, between a monochromatic light travelling in a SU-8 polymer optical waveguide and the biological solution under analysis. Optical simulations of the waveguide coupling to the thin-film photodiode with a specific design were carried out. A prototype was fabricated and characterized showing waveguide optical losses of about 0.6 dB/cm, a photodiode shot noise current of about 2.5 fA/ and responsivity of 495 mA/W at 532 nm. An electro-optical coupling test was performed on the fabricated device to validate the system. As proof of concept, hemoglobin was studied as analyte for a demonstration scenario, involving optical simulations interpolated with experimental data. The calculated detection limit of the proposed system for hemoglobin concentration in aqueous solution is around 100 ppm, in line with colorimetric methods currently on the market. These results show the effectiveness of the proposed system in biological detection applications and encourage further developments in implementing these kinds of devices in the biomedical field.

Quantum nondemolition photon counting with a hybrid electromechanical probe

Quantum nondemolition (QND) measurements of photons is a much pursued endeavor in the field of quantum optics and quantum information processing. Here we propose a novel hybrid optoelectromechanical platform that integrates a cavity system with a hybrid electromechanical probe for QND photon counting. Building upon a mechanical-mode-mediated nonperturbative electro-optical dispersive coupling, our protocol performs the QND photon counting measurement by means of the current-voltage characteristics of the probe. In particular, we show that the peak voltage shift of the differential conductance is linearly dependent on the photon occupation number, thus providing a sensitive measure of the photon number, especially in the strong optomechanical coupling regime. Given that our proposed hybrid system is compatible with state-of-the-art experimental techniques, we discuss its implementations and anticipate applications in quantum optics and polariton physics.

Nonlinear states and dynamics in a synthetic frequency dimension

Recent advances in the study of synthetic dimensions revealed a possibility to employ the frequency space as an additional degree of freedom which allows for investigating and exploiting higher-dimensional phenomena in a priori low-dimensional systems. However, the influence of nonlinear effects on the synthetic frequency dimensions was studied only under significant restrictions. In the present paper, we develop a generalized mean-field model for the optical field envelope inside a single driven-dissipative resonator with quadratic and cubic nonlinearities, whose frequencies are coupled via an electro-optical resonant temporal modulation. The leading-order equation takes the form of a driven Gross-Pitaevskii equation with a cosine potential. We numerically investigate the nonlinear dynamics in such a microring resonator with a synthetic frequency dimension in the regime where parametric frequency conversion occurs. We observe that the modulation brings additional control to the system, enabling one to readily create and manipulate bright and dark dissipative solitons inside the cavity. In the case of anomalous dispersion, we find that the presence of electro-optical mode coupling confines and stabilizes the chaotic modulation instability region. This leads to the appearance of an unconventional type of stable coherent structure which emerges in the synthetic space with restored translational symmetry, in a region of parameters where conventionally only chaotic modulation instability states exist. This structure appears in the center of the synthetic band and, therefore, is referred to as the band soliton. Finally, we extend our results to the case of multiple modulation frequencies with controllable relative phases creating synthetic lattices with nontrivial geometry. We show that an asymmetric synthetic band leads to the coexistence of chaotic and coherent states of the electromagnetic field inside the cavity, i.e., dynamics that can be interpreted as chimeralike states. Recently developed ${\ensuremath{\chi}}^{(2)}$ microresonators can open the way to experimentally exploring our findings.

Emission color-tunable and optical temperature sensing properties of Er3+/La3+ co-doped (K0.5Na0.5)NbO3 optoelectronic transparent ceramic

Transparent Er3+/La3+ co-doped (K0.5Na0.5)NbO3 ceramic was prepared by pressureless sintering. The XRD result shows that it possesses high symmetrical pseudo-cubic perovskite structure without impurity phase. The ceramic owns fine grains with the average size of ∼350 nm, uniform grain distribution, low porosity and high density. The optical transmittance of 0.3-mm ceramic is up to ∼60% in the visible region. Additionally, the ceramic has good dielectric properties with the relaxor-like behavior. Under an excitation of 980-nm, the temperature-dependent up-conversion luminescent color of Er3+ is stable below 523 K and adjustable (changing from green to tangerine color as temperature increases) above 523 K. The ratio of red to green emission intensity with temperature can provide a non-contact luminescent route to roughly detect the phase transition of this ferroelectric ceramic. Furthermore, the fluorescence temperature sensing performance of the ceramic was investigated and the maximum sensitivity is 0.003/K at 380 K. Due to optical, PL and electrical properties, the transparent ceramic shows potential in the application of electro-optical coupling devices.

Electro-optical coupling of a circular Airy beam in a uniaxial crystal.

This paper investigates theoretically and numerically on the electro-optical coupling (EOC) for a circular Airy beam (CAB) propagating along the optical axis of a uniaxial crystal after deducing the wave coupling equations of EOC. For a circularly polarized incident CAB, EOC can be used to generate vortex beam by coupling the incident left-handed component into the right-handed vortex component with a vortex topological charge of 2. What's more, EOC plays important role in enhancing or suppressing the abrupt autofocusing, the most important property of CABs, for both left-handed and right-handed components. Near the focal plane, EOC can result in electrically controllable optical "needle" and "cage", which shall be interesting in micromanipulation. In addition, EOC can influence or even forbid the exchange between spin angular momentum (SAM) and orbit angular momentum (OAM). For a linearly polarized incident CAB, its two Cartesian field components of the beam cannot only couple their powers to each other, but also lead to the changes of the intensity pattern and polarization distributions. The polarization state becomes spatially inhomogeneous, and possesses vortex phase with a topological charge of 2 during propagation. EOC presents a new way to control an Airy beam fast and efficiently.

Simultaneous PET/MR imaging with a radio frequency-penetrable PET insert.

A brain sized radio frequency (RF)-penetrable PET insert has been designed for simultaneous operation with MRI systems. This system takes advantage of electro-optical coupling and battery power to electrically float the PET insert relative to the MRI ground, permitting RF signals to be transmitted through small gaps between the modules that form the PET ring. This design facilitates the use of the built-in body coil for RF transmission and thus could be inserted into any existing MR site wishing to achieve simultaneous PET/MR imaging. The PET detectors employ nonmagnetic silicon photomultipliers in conjunction with a compressed sensing signal multiplexing scheme, and optical fibers to transmit analog PET detector signals out of the MRI room for decoding, processing, and image reconstruction. The PET insert was first constructed and tested in a laboratory benchtop setting, where tomographic images of a custom resolution phantom were successfully acquired. The PET insert was then placed within a 3T body MRI system, and tomographic resolution/contrast phantom images were acquired both with only the B0 field present, and under continuous pulsing from different MR imaging sequences. The resulting PET images have comparable contrast-to-noise ratios (CNR) under all MR pulsing conditions: The maximum percent CNR relative difference for each rod type among all four PET images acquired in the MRI system has a mean of 14.0±7.7%. MR images were successfully acquired through the RF-penetrable PET shielding using only the built-in MR body coil, suggesting that simultaneous imaging is possible without significant mutual interference. These results show promise for this technology as an alternative to costly integrated PET/MR scanners; a PET insert that is compatible with any existing clinical MRI system could greatly increase the availability, accessibility, and dissemination of PET/MR.

On-chip microwave-to-optical quantum coherent converter based on a superconducting resonator coupled to an electro-optic microresonator

We propose a device architecture capable of direct quantum electro-optical conversion of microwave to optical photons. The hybrid system consists of a planar superconducting microwave circuit coupled to an integrated whispering-gallery-mode microresonator made from an electro-optical material. We show that electro-optical (vacuum) coupling rates $g_0$ as large as$\sim 2\pi \, \mathcal{O}(10-100)$ kHz are achievable with currently available technology, due to the small mode volume of the planar microwave resonator. Operating at millikelvin temperatures, such a converter would enable high-efficiency conversion of microwave to optical photons. We analyze the added noise, and show that maximum conversion efficiency is achieved for a multi-photon cooperativity of unity which can be reached with optical power as low as $ \mathcal{O}(1)\,\mathrm{mW} $.

Tunable photoluminescence properties of Pr3+/Er3+-doped 0.93Bi0.5Na0.5TiO3–0.07BaTiO3 low-temperature sintered multifunctional ceramics

Pr3+/Er3+-doped 0.93Bi0.5Na0.5TiO3–0.07BaTiO3 ceramics have been fabricated at a low sintering temperature of 960°C using a sintering aid of Li2CO3. The effects of energy transfer between Pr3+and Er3+on their photoluminescence properties have been investigated. Our results reveal that the down-conversion emissions of Pr3+are weakened and the lifetimes are shortened by the co-doping of Er3+. As a result, when both Pr3+and Er3+are excited simultaneously, with increasing the concentration of Er3+, the green emissions from Er3+increase but the red emissions from Pr3+decrease. Moreover, the emission color of the ceramics can be reversibly changed between red, yellow and yellowish green by using excitation sources of different wavelengths. Strong up-conversion green emissions with short lifetimes arisen from Er3+have also been observed for the ceramics under the excitation of 980nm. Owing to the Li2CO3 sintering aid, the low-temperature sintered ceramics also exhibit reasonably good ferroelectric and piezoelectric properties, and hence should be promising for multifunctional applications such as electro-optical coupling devices.

Mechanical and thermodynamical stability of BiVO4 polymorphs using first-principles study

First principles calculations of structural, electronic, mechanical, and thermodynamic properties of different polymorphs of BiVO4 are performed using Bender-type plane/wave ultrasoft pseudopotentials within the generalized gradient approximation (GGA) in the frame of density functional theory (DFT). The calculated structural and electronic properties are consistent with the previous theoretical and experimental results. The electronic structures reveal that m-BiVO4, op-BiVO4, and st-BiVO4 have indirect band gaps, on the other hand, zt-BiVO4 has a direct band gap. From the DOS and Mulliken’s charge analysis, it is observed that only m-BiVO4 has 6s2 Bi lone pair. Bond population analysis indicates that st-BiVO4 shows a more ionic nature and a similar result is obtained from the elastic properties. From the elastic properties, it is observed that st-BiVO4 is more mechanically stable than the others. st-BiVO4 is more ductile and useful for high electro-optical and electro-mechanical coupling devices. Our calculated thermodynamic properties confirm the similar characteristics found from electronic and elastic properties. m-BiVO4 is useful as photocatalysts, solid state electrolyte, and electrode and other polymorphs are applicable in electronic device fabrications.

Prototype positron emission tomography insert with electro-optical signal transmission for simultaneous operation with MRI

The simultaneous acquisition of PET and MRI data shows promise to provide powerful capabilities to study disease processes in human subjects, guide the development of novel treatments, and monitor therapy response and disease progression. A brain-size PET detector ring insert for an MRI system is being developed that, if successful, can be inserted into any existing MRI system to enable simultaneous PET and MRI images of the brain to be acquired without mutual interference.The PET insert uses electro-optical coupling to relay all the signals from the PET detectors out of the MRI system using analog modulated lasers coupled to fiber optics. Because the fibers use light instead of electrical signals, the PET detector can be electrically decoupled from the MRI making it partially transmissive to the RF field of the MRI. The SiPM devices and low power lasers were powered using non-magnetic MRI compatible batteries.Also, the number of laser-fiber channels in the system was reduced using techniques adapted from the field of compressed sensing. Using the fact that incoming PET data is sparse in time and space, electronic circuits implementing constant weight codes uniquely encode the detector signals in order to reduce the number of electro-optical readout channels by 8-fold.Two out of a total of sixteen electro-optical detector modules have been built and tested with the entire RF-shielded detector gantry for the PET ring insert. The two detectors have been tested outside and inside of a 3T MRI system to study mutual interference effects and simultaneous performance with MRI. Preliminary results show that the PET insert is feasible for high resolution simultaneous PET/MRI imaging for applications in the brain.

Cross-Strip Multiplexed Electro-Optical Coupled Scintillation Detector for Integrated PET/MRI

A prototype electro-optically coupled PET brain insert is being developed for 1.5 T or 3 T MRI systems. To reduce the number of electronic channels, we developed and tested a novel silicon photomultiplier (SiPM) multiplexing circuit based on a novel cross strip readout circuit using capacitors that reduces the number of channels by a factor of 4. Next, we developed and tested this multiplexing circuit with a new electro-optical coupling method that uses a small vertical cavity surface emitting laser (VCSEL) to transmit the scintillation signal out over fiber. This multiplexing circuit is specially suited for directly driving VCSEL lasers without using preamps or any other active components. Two detectors were placed inside the MR bored, and operated with and without a continuos RF field. We were able to resolve a 6 × 6 array of 2.63 mm × 2.63 mm × 20 mm LYSO crystals that were directly coupled to a 4 × 4 array of 3.2 mm × 3.2 mm SiPM pixels with a global delay corrected paired coincidence time resolution 2.50 +/- 0.015 ns FWHM and a per crystal gain corrected energy resolution of 12.6 +/- 0.6% FWHM @511 keV while operating inside an 1.5 T MRI, with or without the RF field on. The two technologies, capacitive multiplexing and electro-optical coupling, have enabled a high-performance clinical PET detector based on silicon photomultipliers, a factor 4 reduction in the number of readout channels, and, when inserted into a 1.5 T MRI system, has low levels of mutual interference between the PET detector and the MRI.

Nanomechanical coupling between microwave and optical photons

A variety of nanomechanical systems can now operate at the quantum limit1,2,3,4, making quantum phenomena more accessible for applications and providing new opportunities for exploring the fundamentals of quantum physics. Such mechanical quantum devices offer compelling opportunities for quantum-enhanced sensing and quantum information5,6,7. Furthermore, mechanical modes provide a versatile quantum bus for coupling hybrid quantum systems, supporting a quantum-coherent connection between different physical degrees of freedom8,9,10,11,12,13. Here, we demonstrate a nanomechanical interface between optical photons and microwave electrical signals, using a piezoelectric optomechanical crystal. We achieve coherent signal transfer between itinerant microwave and optical fields by parametric electro-optical coupling using a localized phonon mode. We perform optical tomography of electrically injected mechanical states and observe coherent interactions between microwave, mechanical and optical modes, manifested as electromechanically induced optical transparency. Our on-chip approach merges integrated photonics with microwave nanomechanics and is fully compatible with superconducting quantum circuits, potentially enabling microwave-to-optical quantum state transfer, and photonic networks of superconducting quantum bits14,15,16.

Novel Electro-Optical Coupling Technique for Magnetic Resonance-Compatible Positron Emission Tomography Detectors

A new magnetic resonance imaging (MRI)-compatible positron emission tomography (PET) detector design is being developed that uses electro-optical coupling to bring the amplitude and arrival time information of high-speed PET detector scintillation pulses out of an MRI system. The electro-optical coupling technology consists of a magnetically insensitive photodetector output signal connected to a nonmagnetic vertical cavity surface emitting laser (VCSEL) diode that is coupled to a multimode optical fiber. This scheme essentially acts as an optical wire with no influence on the MRI system. To test the feasibility of this approach, a lutetium-yttrium oxyorthosilicate crystal coupled to a single pixel of a solid-state photomultiplier array was placed in coincidence with a lutetium oxyorthosilicate crystal coupled to a fast photomultiplier tube with both the new nonmagnetic VCSEL coupling and the standard coaxial cable signal transmission scheme. No significant change was observed in 511 keV photopeak energy resolution and coincidence time resolution. This electro-optical coupling technology enables an MRI-compatible PET block detector to have a reduced electromagnetic footprint compared with the signal transmission schemes deployed in the current MRI/PET designs.

Simultaneous measurements of crystal optical characteristics of deuterated triglycine sulphate

AbstractThe birefringence, rotation angle of the optical indicatrix and the gyration along the polar direction are studied in the paraelectric and ferroelectric phases of deuterated triglycine sulphate crystals using the HAUP‐type universal null‐polarimetric technique. The gyration effect in the multidomain ferroelectric phase is found to be negligibly small, in accordance with the symmetry considerations, while the changes in the birefringence and the indicatrix rotation occurring in the course of the phase transition may be described by electrooptical coupling due to the quadratic spontaneous effect.

Increased efficiency of silicon light-emitting diodes in a standard 1.2-μm silicon complementary metal oxide semiconductor technology

Scaled versions of a variety of silicon light-emitting diode elements (Si LEDs) have been realized using a standard 1.2-µm, doublepolysilicon, double-metal, n-well CMOS fabrication process. The devices operated with a n+p junction biased in the avalanche breakdown mode and were realized by using standard features of the ORBIT FORESIGHT design rules. The elements emit optical radiation in a broad band in the 450- to 850-nm range. An emitted intensity (radiant exitance) of up to 7.1 µW/cm2 (or about 8 nW per 60-µm-diam chip area) has been obtained with 5 mA of current at an operating voltage of 18.5 V. Excellent uniformity in emission intensity of better than 1% variation was obtained over areas as large as 100x500 µm. A best power conversion efficiency of 8.7x 10-8 and a quantum efficiency of 7.8x 10-7 were measured. All of these values are about one order of magnitude better than previously reported values for Si LED avalanche devices. Coupling between the elements as well as electro-optical coupling between an element and an optical fiber was realized.