MEMS-enabled silicon photonic integrated devices and circuits

Photonic integrated circuits have seen a dramatic increase in complexity over the past decades. This development has been spurred by recent applications in datacenter communications and enabled by the availability of standardized mature technology platforms. Mechanical movement of wave-guiding structures at the micro- and nanoscale provides unique opportunities to further enhance functionality and to reduce power consumption in photonic integrated circuits. We here demonstrate integration of MEMS-enabled components in a simplified silicon photonics process based on IMEC's Standard iSiPP50G Silicon Photonics Platform and a custom release process

Compact broadband suspended silicon photonic directional coupler

Directional couplers are extensively used in photonic integrated circuits as basic components for efficient on-chip photonic signal routing. Conventionally, directional couplers are fully encapsulated in the technology's waveguide cladding material. In this Letter, we demonstrate a compact broadband directional coupler, fully suspended in air and exhibiting efficient power coupling in the cross state. The coupler is designed and built based on IMEC's iSiPP50G standard platform, and hydrofluoric (HF) vapor-etching-based post-processing allows to release the freestanding component. A low insertion loss of 0.5 dB at lambda = 1560 nm and a 1 dB bandwidth of 35 nm at lambda = 1550 nm have been confirmed experimentally. With a small footprint of 20 mu m x 30 mu m and high mechanical stability, this directional coupler can serve as a basic building block for large-scale silicon photonic microelectromechanical systems (MEMS) circuits. (C) 2020 Optical Society of Americ

MEMS for Photonic Integrated Circuits

The field of microelectromechanical Systems (MEMS) for photonic integrated circuits (PICs) is reviewed. This field leverages mechanics at the nanometer to micrometer scale to improve existing components and introduce novel functionalities in PICs. This review covers the MEMS actuation principles and the mechanical tuning mechanisms for integrated photonics. The state of the art of MEMS tunable components in PICs is quantitatively reviewed and critically assessed with respect to suitability for large-scale integration in existing PIC technology platforms. MEMS provide a powerful approach to overcome current limitations in PIC technologies and to enable a new design dimension with a wide range of applications

Silicon photonic MEMS add-drop filter

We demonstrate a compact add-drop filter based on a MEMS ring resonator implemented in IMEC's iSiPP50G silicon photonics platform. The device exhibits a port extinction of 20 dB and a port isolation of > 50 dB, upon actuation range of 0 V to 27 V

The draft genome of Kipferlia bialata reveals reductive genome evolution in fornicate parasites

The fornicata (fornicates) is a eukaryotic group known to consist of free-living and parasitic organisms. Genome datasets of two model fornicate parasites Giardia intestinalis and Spironucleus salmonicida are well annotated, so far. The nuclear genomes of G. intestinalis assemblages and S. salmonicida are small in terms of the genome size and simple in genome structure. However, an ancestral genomic structure and gene contents, from which genomes of the fornicate parasites have evolved, remains to be clarified. In order to understand genome evolution in fornicates, here, we present the draft genome sequence of a free-living fornicate, Kipferlia bialata, the divergence of which is earlier than those of the fornicate parasites, and compare it to the genomes of G. intestinalis and S. salmonicida. Our data show that the number of protein genes and introns in K. bialata genome are the most abundant in the genomes of three fornicates, reflecting an ancestral state of fornicate genome evolution. Evasion mechanisms of host immunity found in G. intestinalis and S. salmonicida are absent in the K. bialata genome, suggesting that the two parasites acquired the complex membrane surface proteins on the line leading to the common ancestor of G. intestinalis and S. salmonicida after the divergence from K. bialata. Furthermore, the mitochondrion related organelles (MROs) of K. bialata possess more complex suites of metabolic pathways than those in Giardia and in Spironucleus. In sum, our results unveil the process of reductive evolution which shaped the current genomes in two model fornicate parasites G. intestinalis and S. salmonicida

Heat Shock-Induced Three-Dimensional-Like Proliferation of Normal Human Fibroblasts Mediated by Pressed Silk

The aim of this study was to determine the optimal heat treatment conditions for enhancement of pressed silk-mediated 3D-like proliferation of normal human dermal fibroblasts, as well as to determine the responses to heat shock of cells and intracellular signaling pathways. The beginning of 3D-like pattern formation of cells was observed in the second week after the start of the experiment. The mean rates of beginning of 3D-like pattern formation by cells heat-treated at 40 ºC and 43 ºC for 10 min were significantly higher (3.2- and 8.6-fold, respectively) than that of untreated cells. We found that apoptosis had occurred in 7.5% and 50.0% of the cells at one week after heat treatment for 10 min at 43 ºC and 45 ºC, respectively. Western blot analysis demonstrated that phosphorylation of p38 MAPK and that of Hsp27 were markedly increased by heat treatment at 43 ºC for 10 min. The results of an experiment using a p38 MAPK inhibitor and Hsp27 inhibitor suggest that activation of p38 MAPK by heat shock is associated with 3D-like cell proliferation and that Hsp27 contributes to the inhibition of apoptosis. The results of this study should be useful for further studies aimed at elucidation of the physiologic mechanisms underlying thermotherapy

Clinical characteristics, management strategies and outcomes of patients with recurrent venous thromboembolism in the real world

There is a paucity of data on management strategies and clinical outcomes after recurrent venous thromboembolism (VTE). In a multicenter registry enrolling 3027 patients with acute symptomatic VTE, the current study population was divided into the following 3 groups: (1) First recurrent VTE during anticoagulation therapy (N = 110); (2) First recurrent VTE after discontinuation of anticoagulation therapy (N = 116); and (3) No recurrent VTE (N = 2801). Patients with first recurrent VTE during anticoagulation therapy more often had active cancer (45, 25 and 22%, P < 0.001). Among 110 patients with first recurrent VTE during anticoagulation therapy, 84 patients (76%) received warfarin at recurrent VTE with the median prothrombin time-international normalized ratio (PT-INR) value at recurrent VTE of 1.6, although patients with active cancer had a significantly higher median PT-INR value at recurrent VTE compared with those without active cancer (2.0 versus 1.4, P < 0.001). Within 90 days after recurrent VTE, 23 patients (20.9%) during anticoagulation therapy and 24 patients (20.7%) after discontinuation of anticoagulation therapy died. Active cancer was a major cause of recurrent VTE during anticoagulation therapy as a patient-related factor, while sub-optimal intensity of anticoagulation therapy was a major cause of recurrent VTE during anticoagulation therapy as a treatment-related factor, particularly in patients without active cancer

Integration of MEMS in Silicon Photonics

Like integrated electronics, integrated photonics such as Silicon Photonics benefit from increased device-density on a single chip. Silicon is an excellent material for integrated photonics because its high refractive index allows devices to be made small, and the established silicon CMOS fabrication infrastructure provides a convenient route towards scaling up production. However, standard Silicon Photonics faces a bottleneck in scaling up device-density due to excessive power consumption and high optical losses associated with individual devices. Microelectromechanical systems (MEMS) provide a unique solution to this problem by providing a physical redistribution of optical media to perform the necessary active functions in photonic integrated circuits (PICs) with minimal power consumption and low loss. This thesis tackles two important aspects needed for implementing large-scale MEMS-enabled PICs in silicon. First, the required microfabrication processes are developed for the first-time, by full process integration of MEMS in an established foundry platform, the Interuniversity Microelectronic Centre's (IMEC) iSiPP50G Silicon Photonics technology. By demonstrating MEMS-compatibility, the barrier to adopting this new technology is reduced, and the devices and circuits themselves benefit from co-integration with high-performance standard components. Second, a new class of electrostatic MEMS-enabled photonic building blocks are designed, simulated, and experimentally characterized. Demonstrated devices include a set of remarkably broadband (bandwidth > 80 nm) tunable couplers capable of continuous optical power tuning between output ports to produce extinction ratios greater than 20 dB with minimal insertion loss (reaching < 0.4 dB). In terms of switching, a very low-voltage, six-port count device and a particularly compact (65 um x 62 um) photonic MEMS switch with sub-microsecond switching time are also presented. Further MEMS-enabled functionality is demonstrated with a wavelength-selective add-drop filter and a discussion of phase-shifters and multi-device sub-circuits. These components can be repeated and combined with one another to create complex and reconfigurable networks, and therefore represent an essential stepping stone towards the realization of very large-scale PICs. Together, these key developments in microfabrication and device design promise PIC designers MEMS-enabled photonic components as standard elements in their circuits to efficiently implement functions such as switching, tuning, and filtering for application in photonic switch matrices, weighted interconnects for neural networks, and programmable PICs

Theoretical analysis of the coordination-state dependency of the excited-state properties and ultrafast relaxation dynamics of bacteriochlorophyll a

The coordination-state dependency of the excited-state properties and ultrafast relaxation dynamics from the S₂ to the S₁ state of bacteriochlorophyll a were analyzed using quantum chemical calculations and nonadiabatic molecular dynamics simulations. TDDFT calculations and orbital analysis clarified the molecular mechanism of the decrease in the excitation energy difference caused by ligand coordination. The results of dynamics simulations also showed that the ligand accelerated the relaxation, and the estimated time constant was in quantitative agreement with the experimental data. We demonstrated the importance of the environmental effects for the relaxation dynamics, which have not been investigated theoretically