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We design and experimentally demonstrate highly efficient Silicon Nitride based grating couplers with bottom distributed Bragg reflectors. All the layers were deposited using plasma enhanced chemical vapor deposition processing. We present gratings on two Silicon Nitride thickness (400 nm and 500 nm) platforms. On a 500 nm thick Silicon Nitride, we show a peak coupling efficiency of -2.29 dB/coupler at a wavelength of 1573 nm with a 1 dB bandwidth of 49 nm. On a 400 nm thick platform, we demonstrate a coupling efficiency of -2.58 dB/coupler at 1576 nm with a 1 dB bandwidth of 52 nm. The demonstrated coupling efficiency is the best reported as yet, for both 400 nm and 500 nm thick, plasma deposited Silicon Nitride platforms.

Structural hybridization and size miniaturization of integrated photonic devices are among the hotspots of photonics research field. The crosstalk between densely arranged subwavelength-width optical waveguides such as optical microfibers has become an important issue. Here we investigate a common case of crosstalk in two intersecting subwavelength-diameter optical microfibers at 1550-nm wavelength by numerical simulations and experiments, and obtain the dependence of coupling efficiency and crosstalk on modal polarizations, intersection angle, fiber diameter and separation of the two fibers, respectively. The simulation results show that, the crosstalk decreases with increasing intersection angle and separation between the two microfibers. Especially, for single-mode microfibers, the crosstalk is lower than 1% (i.e., better than -20 dB) when the intersection angle is larger than 60°, and can be minimized to less than 0.05% (i.e., better than -33 dB) for perpendicular intersection (i.e., intersection angle of 90°). However, the dependence of crosstalk on fiber diameter is not monotonous, typically, from the single-mode cutoff diameter, the crosstalk increases with decreasing diameter until reaching a maximum, and decreasing afterward. To verify the simulation, we have experimentally measured the angle-dependent crosstalk between contacting microfibers with typical diameters. With increasing intersection angle, the crosstalk drastically decreases to a negligible value (less than -41 dB for vertically intersecting microfibers), which is consistent with the simulation results. Our results offer a valuable reference or guideline for designing compact optical interconnection and integration with optical microfibers or other subwavelength-width waveguides alike.

Purpose This study intraoperatively measured the coupling efficiency of the Vibrant Soundbridge (VSB), with the aim of avoiding revision surgery due to insufficient outcome. This method can also be used to test the integrity of the implant at the end of the implantation surgery and to evaluate aided thresholds. In addition, this method makes it possible to objectively test how well the VSB has been fitted, provide assistance in fitting handicapped patients or children, evaluate hearing degradation, or test for a drop in coupling efficiency before revision surgeries. In order to analyze the feasibility of these new VSB-aided auditory brainstem response (ABR) thresholds, they were compared to behavioral thresholds from the Vibrogram and the preoperative bone conduction thresholds. Method The study included 30 patients with mild-to-severe hearing loss implanted with a VSB (VORP503). Intraoperative ABR thresholds during the VSB implantation were recorded using a VSB-optimized chirp stimulus. The new method is compared to the bone conduction threshold of the study sample and the aided Vibrogram thresholds. Speech intelligibility results up to 24 months after surgery are also presented. Results A reliable correlation between the bone conduction thresholds and the intraoperative ABRs was found and was higher in comparison to the Vibrogram. Furthermore, speech intelligibility outcomes were stable over time. Conclusion ABR measurements can be used intraoperatively to estimate the coupling efficiency of the VSB and test the integrity of the implant at the end of surgery.

We demonstrate highly efficient couplers in a two-dimensional grating configuration for a vertical fiber-coupling fabricated in the silicon-on-insulator platform. A combination of sub-wavelength reflectors and blazed gratings enables both high coupling efficiency and vertical grating coupling. We experimentally achieve coupling efficiencies of -2.6 dB at 1544 nm and -3.4 dB at 1536 nm for x- and y-polarized LP01 modes, respectively. The experimental results are in good agreement with the simulated -2.4 dB coupling efficiency for both polarizations at a wavelength of 1550 nm. Simulated and measured crosstalk between two polarizations were -19 dB and, IEEE Photonics Journal, 11 (4), ISSN:1943-0655

Secondary active transporters are fundamental to a myriad of biological processes. They use the electrochemical gradient of one solute to drive transport of another solute against its concentration gradient. Central to this mechanism is that the transport of one does not occur in the absence of the other. However, like in most of biology, imperfections in the coupling mechanism exist and we argue that these are innocuous and may even be beneficial for the cell. We discuss the energetics and kinetics of alternating-access in secondary transport and focus on the mechanistic aspects of imperfect coupling that give rise to leak pathways. Additionally, inspection of available transporter structures gives valuable insight into coupling mechanics, and we review literature where proteins have been altered to change their coupling efficiency.

Wavelength selective couplers (WSC) are demonstrated theoretically and experimentally by writing long period gratings (LPGs) in a twin-core fiber (TCF). The coupling characteristics of the wavelength selective coupler are analyzed for different conditions based on the coupled-mode theory. Two LPGs with nearly the same resonant wavelength are written in each core of the TCF by using a high frequency CO2 laser. The experimental results show that the LPGs in the TCF can couple the light from one core to the other and a peak coupling efficiency of 42% has been achieved. Our results prove the viability of realizing an integrated wavelength selective coupler by using the configuration of TCF with LPFs.

Flexible organic light-emitting diodes (OLEDs) have attracted a great attention in the lighting market because of their exciting advantage to be fabricated as a freely shaped illumination source with no design restrictions. However, flexible OLEDs are difficult to commercialize due to their low power efficiency compared to fluorescent or inorganic light-emitting diodes. Accordingly, effective optical extraction techniques are needed to address this issue. In this study, we report development of a flexible OLED device fabricated on a poly-para-xylylene (parylene) substrate patterned with a micro-lens array (MLA). Ultra-thin parylene films were successfully applied as flexible polymer substrates for foldable OLEDs with enhanced out-coupling efficiency. It was confirmed that MLA-patterned parylene substrates do not have any negative impacts on the electrical properties of the OLEDs. On the contrary, the flexible OLEDs fabricated on these substrates for light extraction exhibited the current efficiency enhanced by a factor of 1.23 compared to the reference OLED. Thus, we present a simple and low-cost OLED fabrication method to enhance the light extraction out of flexible OLEDs.

The coupling efficiency of the slow-wave propagation mode along the cochlea was investigated by evaluating the overlap integral of the acoustic field on two adjacent cross-sectional planes. The dispersion diagrams of the fast- and slow-wave modes and the structural dependence of the angular wavenumber and coupling efficiency of the slow-wave mode were studied.

We study the effect of lateral error on the coupling efficiency and beam quality of a Gaussian beam coupled into a large-core multimode fiber. The formula for the effect of lateral error on coupling efficiency is derived in detail and verified with both simulations and experiments. The effect of lateral error on beam quality is also analyzed with the use of ZEMAX and verified with our experimental setup. The results show that lateral error can change the path of the light coupled into the fiber to such a large extent that it influences the power distribution of the Gaussian beam.

By means of the ABCD matrix relation under paraxial approximation, a simple method to calculate the coupling efficiency for laser diode coupling to cylindrical lensed fiber is presented. The allowable aperture is taken into consideration in our formalism. The mathematical model agrees excellently with earlier work. For the first time various coupling parameters are numerically optimized with the help of gradient method in order to make the coupling more efficient. A cylindrical lensed fiber coupling system is presented with a maximum coupling efficiency up to 94.23%. The effects of fiber tip radius and fiber core radius on coupling efficiency are also studied. Calculations presented in this study are executable by a pocket calculator. The results will guide the design of cylindrical lensed fiber coupling systems.

In this paper, the relationship between the coupling efficiency and transmission distance of different fiber optic probes is compared for further studying the focusing performance of ultra-small GRIN fiber probes. Taking an example of five typical ultra-small GRIN fiber probes such as single mode fiber (SMF), "SMF + 0.31mm 50/125 GRIN", "SMF + 0.36mm NCF + 0.12mm 50/125 GRIN", "SMF + 0.48mm 100/140 GRIN", "SMF + 0.48mm NCF + 0.14mm 50/125 GRIN", the relationships between the theoretical coupling efficiency and transmission distance are compared with experimental data. The obtained results show that an increase in the working distance of a probe causes increase of the transmission distance to maintain a higher coupling efficiency, and leads to gain of the waist diameter. Therefore, the comprehensive effects of the working distance, waist diameter and coupling efficiency must be taken into consideration in the process of optimizing the design parameters of ultra-small GRIN fiber probes.

The effect of alignment error on the coupling efficiency and beam quality of a Gaussian beam coupled into a large-core multimode fiber is studied in this paper. The equations for evaluating the effect of alignment error on the coupling efficiency are derived separately, and verified with the method of simulation. The calculation and simulation results obtained are highly consistent. In the same way, the effects of alignment error on the beam power distribution are discussed. The results show that the lateral error will change the path of partial light to a large extent, and have a greater influence on the power distribution of the Gaussian beam than the longitudinal error and angular error do. Keywords: Alignment error, Coupling efficiency, Beam quality, Multimode fiber

In the present work, properties of the interlayer breathing modes in twisted MoS2 samples with different structures are carefully examined. The distribution of peak position of the breathing modes is mainly dependent on overall layer numbers, and is only slightly affected by specific structure of the sample. Linear chain model calculation shows quantitatively a markedly decrease in interlayer force on the twisted interface, and slight difference in Raman frequency may mean considerable difference in interlayer force. When one or both of the component layers get too thick, no new breathing modes can be found, indicating that rigidity of the component may affect the coupling efficiency. Our work demonstrates that low-frequency Raman spectroscopy can act as an effective indirect strategy for the detection of interlayer interaction, which is a good complement to existing methods such as AFM technologies.

The Glaser-Hay bioconjugation has recently emerged as an efficient and attractive method to generate stable, useful bioconjugates with numerous applications, specifically in the field of therapeutics. Herein, we investigate the mechanism of the aqueous Glaser-Hay coupling to better understand optimization strategies. In doing so, it was identified that catalase is able to minimize protein oxidation and improve coupling efficiency, suggesting that hydrogen peroxide is produced during the aqueous Glaser-Hay bioconjugation. Further, several new ligands were investigated to minimize protein oxidation and maximize coupling efficiency. Finally, two novel strategies to streamline the Glaser-Hay bioconjugation and eliminate the need for secondary purification have been developed.

This work demonstrated an effective strategy for the capture, identification and determination of multiple types of circulating tumor cells (CTCs) on functional and biocompatible immunomagnetic nanosphere interfaces (IMNs). The IMNs were achieved by functionalizing superparamagnetic iron oxide nanospheres (Fe3O4) with polymerized ionic liquid (PIL), and then coating with epithelial-cell-adhesion-molecule antibody (anti-EpCAM). The IMNs exhibited outstanding cell capture efficiency (above 95%) and specificity when employed to separate multiple EpCAM-positive tumor cells, due to the abundant carboxyl groups in the structure of PIL, which enhanced the coupling efficiency of MNs with anti-EpCAM by chemical bonding between carboxyls and amines, thereby enabling more target cells adhered onto IMNs. Under the optimized capture conditions, IMNs were shown an excellent cell capture performance in the range of 5–400 cells/mL in three different cases (e.g., PBS, MCF-7 and THP-1 mixed cell suspension, lysed blood). More significantly, our results indicated that with modification of PIL, in addition to the capture efficiency, the cell viability rate of CTCs was also greatly improved (98%) owing to the nontoxic and biocompatible properties of PIL, which realized the proliferation of the rare number CTCs for further molecular characterization. Finally, the IMNs were successfully applied to the isolation and detection of CTCs in cancer patient peripheral blood samples and as low as one CTC in the whole blood was captured and identified by the ICC method.

It has been proposed that a loss of bioenergetic capacity of cells contributes to the progressive loss of biological function with age. Aging is associated with loss of mitochondrial cristae membranes and inhibition of ATP production. Despite the many approaches being pursued for improving mitochondrial function, none of them directly targets the electron transport chain to improve ATP production. Recent studies have brought attention to cardiolipin as a unique target for promoting mitochondrial efficiency. Cardiolipin is important for cristae curvatures and is necessary for optimal activity of the respiratory complexes and the assembly of supercomplexes. Here we describe the discovery of a class of cell-penetrating aromatic-cationic tetrapeptides that selectively target cardiolipin and increase coupling efficiency while reducing reactive oxygen species production. These compounds can rejuvenate mitochondrial bioenergetics, remodel mitochondrial cristae structure, repair cellular structure, and restore organ function during aging.

A study of the effect on the coupling efficiency due to surrounding refractive index and fusion depth variations in (1+1) side-pump combiners is presented. The external refractive index values used in the simulations are 1.0 and 1.35, which correspond to the refractive indexes of air and Teflon. The results showed that the coupling efficiency is not affected by a Teflon-like surrounding medium along the coupling zone as long as the tapers transition of the pump fiber is not too large to reduce the propagation angle below the critical angle of the receiving double clad fiber. Furthermore, modal simulations showed that the higher the fusion depth the faster the coupling of the pump modes.

The slime mold Dictyostelium discoideum’s life cycle includes different unicellular and multicellular stages that provide a convenient model for research concerning intracellular and intercellular mechanisms influencing mitochondria’s structure and function. We aim to determine the differences between the mitochondria isolated from the slime mold regarding its early developmental stages induced by starvation, namely the unicellular (U), aggregation (A) and streams (S) stages, at the bioenergetic and proteome levels. We measured the oxygen consumption of intact cells using the Clarke electrode and observed a distinct decrease in mitochondrial coupling capacity for stage S cells and a decrease in mitochondrial coupling efficiency for stage A and S cells. We also found changes in spare respiratory capacity. We performed a wide comparative proteomic study. During the transition from the unicellular stage to the multicellular stage, important proteomic differences occurred in stages A and S relating to the proteins of the main mitochondrial functional groups, showing characteristic tendencies that could be associated with their ongoing adaptation to starvation following cell reprogramming during the switch to gluconeogenesis. We suggest that the main mitochondrial processes are downregulated during the early developmental stages, although this needs to be verified by extending analogous studies to the next slime mold life cycle stages.

The single-mode fiber coupling efficiency with graded-index rod lenses can achieve higher coupling efficiency, compared with the direct alignment coupling of the single-mode fiber. The assembly error of direct alignment has a far greater impact on the coupling efficiency of the fiber than the GRIN lenses coupling to fiber. The analysis of the influence of the coupling error on the optical fiber coupling efficiency provides important theoretical support and guidance for processing and assembly. Axial error, radial error and angular tilt will all have different effects on fiber coupling efficiency. However, the fiber coupling system is not only limited to the coupling of the fiber and GRIN lenses, but also can be coupled with one or more lenses to analyze the advantages and disadvantages of multiple coupling methods.

Review of the latest progress of special optical fiber applications in laser optics, IR-Imaging and spectrometry. The advanced fiber solutions will be presented for Quantum Cascade Lasers in Mid-IR range. A high coupling efficiency of optical fiber and Hollow Waveguides to QCL is demonstrated. A novel combined fiber optic multispectral probe for tissue diagnostics is demonstrated and discussed. Flexible solutions for thermal imaging in mid-IR range are proposed on the base of high quality optical fibers.

We have been investigating an optical phased array (OPA) using an electro-optic (EO) polymer, that can control the shape and direction of an optical beam at high speed. In this study, we propose an OPA which consists of hybrid waveguides with organic and inorganic optical core materials. By applying the taper structure to the inorganic core at the connection part, we inproved coupling efficiency.

Eosin Y was assessed for its ability to induce a thiol–ene dependent protein–protein reaction in a metal-free, oxygen-tolerant, visible light mediated system. Protein–protein coupling efficiency under these mild conditions was comparable to previously reported UV-dependent conditions. The desired thiol–ene reaction was however limited within more complex biological systems.

One-dimensional polarization-independent grating couplers are demonstrated with the aid of the adaptive genetic algorithm optimization. By adjusting the relative weight between the coupling efficiency and the bandwidth of the polarization-dependent loss (PDL), we control the evolution direction and customize the final performance of the device. Two specific designs are generated by giving more weight to the coupling efficiency and the PDL bandwidth, respectively. Coupling efficiencies of the first design are measured to be − 7.6 d B and − 7.9 d B at 1550 nm for TE and TM polarizations, respectively, while its 1.0 dB PDL bandwidth is 25.0 nm. In contrast, the second design presents higher coupling efficiencies of − 7.6 d B and − 7.2 d B at 1550 nm for TE and TM polarizations, respectively. However, its 1.0 dB PDL bandwidth is 22.0 nm.

InP-based PICs with waveguide p-i-n PDs for 100 GBaud coherent receivers are demonstrated. The wide 3-dB bandwidth of more than 65 GHz and high responsivity of 0.154 A/W are revealed at a wavelength of 1.55 μm. We successfully achieve the monolithic integration of 19 functions as InP-based PICs with a footprint of 10.7 mm2.

We demonstrate a recess-type Ge on Si WGAPD receiver with 106Gb/s PAM4 overload >0dBm and unstressed/stressed sensitivities of -18.9/18dBm, which provides about 19dB dynamic range for 100Gb/s per lane applications.

Metallic grating couplers can be extremely broadband and efficient. In this work, we investigate an all-plasmonic fiber-to-chip coupler with a coupling efficiency of -2.7 dB and an optical 3-dB passband of 300 nm.

This paper gives an overview of the recent trends of FSO systems for B5G/6G era, covering transceiver design, system architectures and integration with mmWave/THz links. The potential implementation of machine learning algorithms is also discussed.

We show theoretically that the coupling efficiency between a gaussian beam and the fundamental mode of nested antiresonant hollow-core optical fibers exceeds 97% and depends on the order of the antiresonance window.

Optical slot waveguide was demonstrated in the mid-infrared at 4.2 μm for gas sensing application on Germanium-on-silicon platform. 0.47 ppm of limit-of-detection for carbon dioxide can be achieved with enhanced confinement factor and propagation loss.

We demonstrate low-loss fiber-to-chip coupling via a-Si grating couplers on top of SiN waveguides for C-band TE light. The suggested simple scheme is fabrication tolerant and offers a path towards coupling efficiencies above -1 dB.

We demonstrate the creation of permanent, localized strain structures in hBN with a phonon-resonant femtosecond laser at 7.3 µm. We spatially resolve the strain profile of the resulting micron-scale bubbles using Raman and AFM measurements.

Temperature-stable single-mode 850 nm VCSELs with integrated mode-selective filters are developed and demonstrated record NRZ 38 Gb/s (25 °C), NRZ 32 Gb/s (70 °C) and PAM4 32 GBaud (25 °C) on 1 km standard single-mode fiber (SMF-28).

We examined light propagation along the spot size converter of silicon photonic wire waveguides, and show there are two maxima in coupling efficiency. An optimal design was given in terms of compactness and high efficiency by changing its dimension and shape.

Through phase matching optimization, an acoustically induced tunable in-fiber Mach-Zehnder interferometer less than 7 cm with 120 μs switching time based on a sandwich-like structure with uniform diameter was proposed and demonstrated in the experiment.