Experimental demonstration of broadband Lorentz non-reciprocity in an integrable photonic architecture based on Mach-Zehnder modulators

We demonstrate the first active optical isolator and circulator implemented in a linear and reciprocal material platform using commercial Mach-Zehnder modulators. In a proof-of-principle experiment based on single-mode polarization-maintaining fibers, we achieve more than 12.5 dB isolation over an unprecedented 8.7 THz bandwidth at telecommunication wavelengths, with only 9.1 dB total insertion loss. Our architecture provides a practical answer to the challenge of non-reciprocal light routing in photonic integrated circuits.Comment: include Appendix, 9 figures and 2 table

Characterization of hydrophilic and hydrophobic core-shell microcapsules prepared using a range of antisolvent approaches

This study describes three straightforward approaches to leveraging gel network-restricted antisolvent precipitation techniques as a means of preparing hydrophilic hydrophobic core-shell microparticles. Briefly, hydrophilic polysaccharides (sodium alginate (ALG), κ-carrageenan (CAR), and agar (AG)) were utilized to prepare microgel beads that were then immersed in zein solutions (70% ethanol aqueous solution, 70% urea aqueous solution, and zein in 70% acetic acid, respectively), thereby facilitating the controlled, slow antisolvent precipitation of the protein layer on the microbead surfaces and inducing hydrophilic hydrophobic core-shell structure formation. This technique can be readily applied to a range of gelling systems and can be tailored to target particle sizes and shell thicknesses. The resultant core-shell particles offer great promise for controlled delivery of fragrances, drugs, or other bioactive compounds in an application-specific fashion, and can be individually tailored based upon the selected input concentrations and preparation methods. Importantly, this technique is generalizable and can be extended to prepare diverse particles with a range of core-shell structures produced from a wide assortment of hydrophobic materials

Preparation and characterization of gliadin-based core-shell microcapsules by three antisolvent approaches

Gliadin, a versatile wheat-derived protein, has great potential in the creation of nanostructured delivery systems for encapsulating various hydrophobic bioactive substances. Despite gliadin's well-established potential in creating nanostructured delivery systems for hydrophobic substances, its utilization for encapsulating hydrophilic compounds remains a relatively unexplored domain. This study investigated the feasibility of preparing gliadin-based core-shell microcapsules using different antisolvent methods and assessed their controlled release capabilities for hydrophilic compounds. It employed three commonly used food polysaccharides, alginate, κ-carrageenan, and agar, as hydrophilic microbeads and selected thiamine and ethyl maltol as model compounds. The microcapsules were constructed by two steps: 1) The microbeads were prepared by a water-in-oil emulsion template under different gelling conditions; 2) The microbeads were dispersed into aqueous ethanol/urea/acetic acid gliadin solutions, during which the slow migration of water from inside the microbeads to the outer gliadin solution decreased the solubility of gliadin and promoted the deposition of gliadin onto the surface of the microbeads, finally leading to the formation of the core-shell structure. The resulting core-shell microcapsules exhibited adjustable particle sizes from 80.0 to 850.0 μm in diameter and shell thickness ranging from 8.0 to 30.0 μm. Moreover, the microcapsules exhibited controlled release behavior for hydrophilic compounds, with only 20.0% of thiamine being released after 90 min, and this release rate can be finely tuned by controlling the shell thickness. These gliadin-based core-shell microcapsules are considered as promising carriers for the controlled delivery of hydrophilic compounds

Silicon photonic transmitter for polarization-encoded quantum key distribution

Silicon (Si) photonics is forming a fabless ecosystem, which is enabling low-cost and densely integrated components for optical communications and quantum information. We present a Si optical transmitter for polarization-encoded quantum key distribution (QKD). The chip was fabricated in a standard Si photonic foundry process and integrated together a pulse generator, intensity modulator, variable optical attenuator, and polarization modulator in a 1.3  mm×3  mm1.3  mm×3  mm die area. The devices in the photonic circuit meet the requirements for QKD. The transmitter was used in a proof-of-concept demonstration of the BB84 QKD protocol over a 5 km long fiber link. This work shows the potential of using foundry Si photonics for low-cost, wafer-scale fabricated components for quantum information

A CMOS-compatible silicon photonic platform for high-speed integrated opto-electronics

We have developed a CMOS-compatible Silicon-on-Insulator photonic platform featuring active components such as p- i-n and photoconductive (MIM) Ge-on-Si detectors, p-i-n ring and Mach-Zehnder modulators, and traveling-wave modulators based on a p-n junction driven by an RF transmission line. We have characterized the yield and uniformity of the performance through automated cross-wafer testing, demonstrating that our process is reliable and scalable. The entire platform is capable of more than 40 GB/s data rate. Fabricated at the IME/A-STAR foundry in Singapore, it is available to the worldwide community through OpSIS, a successful multi-project wafer service based at the University of Delaware. After exposing the design, fabrication and performance of the most advanced platform components, we present our newest results obtained after the first public run. These include low loss passives (Y-junctions: 0.28 dB; waveguide crossings: 0.18 dB and cross-talk -41±2 dB; non-uniform grating couplers: 3.2±0.2 dB). All these components were tested across full 8” wafers and exhibited remarkable uniformity. The active devices were improved from the previous design kit to exhibit 3dB bandwidths ranging from 30 GHz (modulators) to 58 GHz (detectors). We also present new packaging services available to OpSIS users: vertical fiber coupling and edge coupling

Toward non-reciprocal chip-scale silicon photonics

Mirotznik, Mark S.Hochberg, MichaelA critical problem in modern photonics is the optical isolation. An optical isolator allows light to pass through in one direction but blocks it in the other, thereby acting as the optical analogue of an electronic diode. Because such a device induces a preferred direction for light, it must break the symmetry of Maxwell's equations known as Lorentz reciprocity. This dissertation focuses on the reciprocity breaking photonic architecture that is comprised of optical modulators under prescribed driving conditions, optical delay lines and directional couplers in the silicon photonic platform. Unlike isolators based on magneto-optical Kerr effects or nonlinear effects, the author's non-reciprocal system is built by silicon photonic devices in the linear and reciprocal material platform. The system that works as the optical isolator and circulator at the same time is demonstrated by a fiber-based proof-of-concept experiment. The system architecture provides a practical answer to the challenge of non-reciprocal light routing in photonic integrated circuits (PICs). A silicon optical modulator that can satisfy the non-reciprocal system's demands is studied. The application of the PN junction's nonlinearity in the modulator can improve the robustness of the non-reciprocal system by removing the signal distortion's influence. The high-linear Mach-Zehnder modulator in silicon is also presented. The phase coherence length of the silicon photonic platform is studied to fulfill a reliable non-reciprocal system. The coherence length can quantitate the semiconductor fabrication uniformity that is critical in the design of complex PICs. A new method is proposed to analyze the random phase fluctuations from more than 800 on-chip silicon Mach-Zehnder interferometers across the wafer. For the first time, the waveguide coherence length of silicon photonic platform is extracted with statistical significance. Finally, a fabrication error model is proposed in order to effectively design the low loss compact directional coupler. High consistent performance of device is verified by experiments.University of Delaware, Department of Electrical and Computer EngineeringD.Eng

Mineralogical and geochemical study of apatite and dolomite from the Bayan Obo giant Fe-REE-Nb deposit in Inner Mongolia: New evidences for genesis

The Bayan Obo Fe-REE-Nb deposit is the world's largest resource of REE and its origin still remains controversial. To decipher the genesis of this unique deposit, we conducted a detailed mineralogical observations using scanning electron microscope (SEM), cathodoluminescence (CL) and in-situ micro-analyses on chemical compositions of the dolomite and apatite by EPMA and LA-ICPMS techniques. A wide range in SrO contents in dolomite mineral grains from coarse-grained dolomite marble has been observed. The SrO contents in the margin of the dolomite mineral reach up to 1.04 wt%, while the SrO contents in the core are as low as 0.16 wt%. In contrast, the SrO contents of the dolomite minerals of fine-grained dolomite marble are basically invariable, mainly concentrating on the range of 0.1 wt%-0.2 wt%. The MnO and FeO concentrations of dolomite mineral grains from the coarse-grained dolomite marble (MnO, 0.24 wt%-0.45 wt%; FeO, 2.27 wt%-3.42 wt%) are significantly lower than those of dolomite from fine-grained dolomite marble (MnO, 0.84 wt%-3.32 wt%; FeO, 3.59 wt%-12.16 wt%). The big differences in major elements between two types of the H8 dolomite marble imply different forming processes. Three types of apatite show big differences in cathodoluminescent signatures, major and trace elements. Type I fluorapatite has few REE mineral inclusions and Type II fluorapatite hosts abundant tiny REE mineral (monazite) inclusions. Type III fluorapatite from strongly deformed coarse-grained dolomite marble forms abnormally large monocrystals with elongated orientation. Both Type I and Type II fluorapatite from fine-grained dolomite marble samples display the heterogeneous component regions under BSE, with obvious depletion in Na and REE in BSE-dark areas observed in the X-ray compositional maps. Unaltered (BSE-bright) regions in Type I and Type II fluorapatite have high REE (17470-77090 ppm), Y (714-8162 ppm), Na (2023-10258 ppm), Sr (2126-6422 ppm) concentrations, obviously different from Type III fluorapatite (REE, 2452-7496 ppm; Y, 157-285 ppm; Na, 501-1464 ppm; Sr, 6878-9949 ppm). The REE, Na, Th and Pb depletion in BSE-dark regions in Type I and Type II apatite correspond to two styles of REE re mobilization during fluid-induced dissolution-reprecipitation processes. Late-stage REE, Na, Ba, CO32-, SO42- rich mesothermal hydrothermal fluid evolved from carbonatite was responsible for REE leaching in Type I fluorapatite. The Sr-rich, Na-poor, REE-poor Type III fluorapatite and associated elevated SrO contents in the margin of dolomite imply that the deposit underwent subsequent fluid infiltration by Sr-rich, REE-poor, Na-poor metamorphic fluid, causing the REE leaching in Type II fluorapatite and the consequent formation of monazite inclusions. As a common REE-bearing mineral in Bayan Obo deposit, apatite displays a diversity of textures and occurrences, fingerprints multi-stage metasomatic fluids and provides new insights into the mechanism of REE enrichment and remobilization

Towards Flexible, Scalable and Low Loss Non-reciprocal System in Silicon Photonics

A silicon photonic non-reciprocal isolator/circulator system with time-dependent permittivity tensor is demonstrated. In addition to being broadband and low loss, the architecture is scalable to achieve high extinction ratio with reconfigurable isolation path direction