Improve Coupling Efficiency Research Articles

Spectrum contrast enhancement of fiber fabry-perot sensor by coupling efficiency improvement

This paper investigates the impact of interface angles on the coupling efficiency of a fiber Fabry-Perot interferometer (FFPI) sensor using both simulation and experimental methods. The FFPI sensor, which consists of a single-mode fiber (SMF), hollow-core fiber (HCF), and diaphragm, has its coupling efficiency determined by the generalized scattering matrix of the cascaded fiber system. To obtain the interface angles of the FFPI sensor, a new on-line monitoring system is developed based on microscopic images of the FFPI cavity and an image processing algorithm using OpenCV. By combining the eigenmode expansion method (EME) model and the online interface angle measurement technique, the coupling efficiency and spectral contrast of the FFPI cavity are evaluated and improved. Additionally, the corresponding working point in the intensity demodulation based FFPI sensor can be quickly identified. Using this method, an FFPI sensor with a spectral contrast of over 35 dB is achieved, which is significantly higher than existing similar sensors, and its sensitivity also reaches 50.80 mV/MPa. This work also holds significance for controlling and enhancing the spectral characteristics of other cascaded fiber optic sensors.

Solar-blind ultraviolet emission-detection monolithic integration of AlGaN multiple-quantum-well diodes via concentric ring-circle configuration

AlGaN multiple-quantum-well diode-based solar-blind ultraviolet emission-detection monolithic integration system shows great application value due to its advantages of multifunctionality, secure communication, and anti-interference ability. To reduce the lateral optical propagation loss and improve the emitting light detection efficiency, we have proposed a concentric ring-circle configuration for the system, where the out-ring light-emitting diode is the emitter at 253 and 267 nm, and the inner-circle detector is the receiver. The out-ring light-emitting diode exhibits about twice the injection current at the same bias and slightly higher light output power at the same current due to better current spreading and sidewall light extraction compared to the conventional square–square configuration. Simultaneously, the concentric inner-circle detector maximizes the collection of the emitted light flux. Under the emission-detection mode for the monolithic integration system, compared to the conventional square–square configuration, the concentric ring-circle design presents an improvement in the ratio of emitter injection current to detector output photocurrent and higher output signal amplitude under the same transmission work mode, demonstrating the improved system energy and coupling efficiency. This design provides a potential approach to achieve low power consumption and high bandwidth in the monolithic integrated optoelectronic chips.

Engineering luminopsins with improved coupling efficiencies.

Luminopsins (LMOs) are bioluminescent-optogenetic tools with a luciferase fused to an opsin that allow bimodal control of neurons by providing both optogenetic and chemogenetic access. Determining which design features contribute to the efficacy of LMOs will be beneficial for further improving LMOs for use in research. We investigated the relative impact of luciferase brightness, opsin sensitivity, pairing of emission and absorption wavelength, and arrangement of moieties on the function of LMOs. We quantified efficacy of LMOs through whole cell patch clamp recordings in HEK293 cells by determining coupling efficiency, the percentage of maximum LED induced photocurrent achieved with bioluminescent activation of an opsin. We confirmed key results by multielectrode array recordings in primary neurons. Luciferase brightness and opsin sensitivity had the most impact on the efficacy of LMOs, and N-terminal fusions of luciferases to opsins performed better than C-terminal and multi-terminal fusions. Precise paring of luciferase emission and opsin absorption spectra appeared to be less critical. Whole cell patch clamp recordings allowed us to quantify the impact of different characteristics of LMOs on their function. Our results suggest that coupling brighter bioluminescent sources to more sensitive opsins will improve LMO function. As bioluminescent activation of opsins is most likely based on Förster resonance energy transfer, the most effective strategy for improving LMOs further will be molecular evolution of luciferase-fluorescent protein-opsin fusions.

Optimization of Circular Coils with Ferrite Boxes for Enhanced Efficiency in Wireless Power Transfer for Electric Vehicles

This study responds to global climate concerns by addressing the shift towards sustainable transportation, particularly electric vehicles. Focusing on wireless power transfer to overcome charging infrastructure challenges, the research optimizes circular coils for inductive power transfer in electric cars. Utilizing ferrite cores to enhance performance, the study employs ANSYS Electronics Suite R2-202 and the finite element method to analyze circular coils, exploring variations in turns, inner radius, air gap, and misalignment's impact on the coupling coefficient. Introducing ferrite plan cores and boxes, the research finds that ferrite boxes improve coupling efficiency by 50% and electromagnetic field strength by 300%, concentrating the field toward the center. An inequivalent design, enlarging the primary coil, demonstrates significant enhancements, achieving a coupling coefficient increase of 0.183447 and an electromagnetic field rise of 0.00040 Tesla. Equivalent coils with ferrite boxes meet a 95% efficiency goal with a strong, narrowed field at a lower cost, while inequivalent coils excel in strengthening and centralizing the field, enhancing misalignment tolerance in distinctive ways.

Reliable and easy-to-use SERS spectroscopy probe using a tapered opto-fluidic photonic crystal fiber.

Surface enhanced Raman spectroscopy (SERS) is one of the most sensitive biosensing techniques that offers label free detection for a variety of applications. Generally, SERS spectroscopy is performed on nano-functionalized planar substrates with plasmonic structures or colloidal nanoparticles. Recently, photonic crystal fibers (PCFs) have gained great interest for SERS based bio sensing applications due to the immense advantages such as improved sensitivity, flexibility and remote sensing capability that it offers compared to the planar substrates. However, the use of PCF based biosensors demand the alignment of it under a microscope, which can affect the reliability of SERS measurements and could be restrictive for practical end use applications. Herein, we aim to develop a tapered suspended core PCF fiber (Tapered-SuC-PCF) that represents an improvement in coupling efficiency and measurement reliability as well as it opens the way to the development of an easy-to-use bio-sensing probes with a plug and play option with conventional Raman spectrometers. We have fabricated several samples of the optimized tapered-SuC-PCF and demonstrated its superior SERS performance compared to standard SuC-PCF fibers with 2 µm core diameter. An excellent SERS measurement reliability is demonstrated using such a fiber in a plug and play type system demonstrating its versatility for practical end use applications.

Hollow metal tubes for efficient electron manipulation using terahertz surface waves.

Compact electron sources have been instrumental in multidiscipline sciences including fundamental physics, oncology treatments, and advanced industries. Of particular interest is the terahertz-driven electron manipulation that holds great promise for an efficient high gradient of multi-GeV/m inside a regular dielectric-lined waveguide (DLW). The recent study relying on terahertz surface waves has demonstrated both high terahertz energy and improved coupling efficiency with the DLW. However, the large energy spread pertaining to the laser-induced electron pulse impedes the practical use of the system. Here, we propose a scheme for extending the idea of surface-wave-driven electron manipulation to mature electron sources such as commercial direct-current and radio-frequency electron guns. By using a simple hollow cylinder tube for electron transmission, we show that the electron energy modulation can reach up to 860 keV, or compress the electron pulse width to 15 fs using a 2.9 mJ single-cycle terahertz pulse. The trafficability of the hollow tube also allows for a cascade of the system, which is expected to pave the way for compact and highly efficient THz-driven electron sources.

Design and Experimental Analysis of an Optical Fiber Coupling System for a Ground-based Telescope with Adaptive Optics

Astronomy photonics has opened up a new era for the application of astronomical optical instruments. The fiber coupling system serves as the crucial link between the telescope and photonic devices. This paper explores a beam shaping method that utilizes a coupled lens to enhance the efficiency of coupling light into an optical single mode fiber. Compared to directly coupling the telescope beam into the fiber, this approach offers improved coupling efficiency and greater adjustment tolerance. The laboratory-based optical fiber coupling system described in this study comprises an imaging component with an F/50 ratio and a fiber coupling component. Theoretical analysis indicates that optimal coupling efficiency is achieved when the diameter of the focusing spot, limited by diffraction, matches the fiber core size. Any axial error, position error, or tip-tilt error between the lens and the fiber will reduce the coupling efficiency. Experimental results confirm that the coupling system achieves an efficiency of approximately 70%, which is close to the theoretical limit of 78%. These findings underscore the effectiveness of the fiber coupling method.

Efficient Light Coupling and Purcell Effect Enhancement for Interlayer Exciton Emitters in 2D Heterostructures Combined with SiN Nanoparticles.

Optimal design of a silicon nitride waveguide structure composed of resonant nanoantennas for efficient light coupling with interlayer exciton emitters in a MoSe2-WSe2 heterostructure is proposed. Numerical simulations demonstrate up to eight times coupling efficiency improvement and twelve times Purcell effect enhancement in comparison with a conventional strip waveguide. Achieved results can be beneficial for development of on-chip non-classical light sources.

Application of data elements in the coupling of finance and technology on the digital electronic platform

With the continuous development of Internet technology, all areas of social economy have undergone profound changes. The circulation and application of data elements can significantly promote the construction of infrastructure such as big data centers and mobile base stations, and stimulate the market demand for digital consumption such as digital production, e-commerce and digital trade. Data mining technology will provide sustainable impetus for economic development. There is a clearer analysis of the role of data elements in the platform economy, but there is a lack of research in macroeconomics, especially in the coupling of finance and technology. This paper developed a coupling coordination and a coupling efficiency index system, using different methods to measure outcomes and outline the path to achieving high "quantity" and "quality" of finance-technology coupling development. Based on the data mining technology in e-commerce, the fuzzy set qualitative comparative analysis method is used to analyze the complex mechanisms and driving paths of data elements affecting the coordination degree and coupling efficiency of finance-technology coupling performance of China. We empirically document that data mining and data management are necessary to improve coupling coordination; in the absence of other conditions, data mining or data management can produce high coupling coordination, but not sufficient to improve coupling efficiency.

Control of low-mode drive asymmetry in an efficient long-pulse low gas-fill density Hohlraum

Laser-driven Hohlraums filled with gas at lower densities (<0.6 mg/cc) have higher efficiency compared to original ≥ 0.96 mg/cc fill because of reduced backscatter losses [Hall et al., Phys. Plasmas 24, 052706 (2017)]. However, using low-density filled Hohlraums with longer drive required for lower adiabat implosions, and hence potentially higher inertial confinement fusion gain designs, has been challenging since the Hohlraum wall blow-off is less tamped, thus altering the laser beam absorption regions and drive symmetry. A series of NIF experiments using optimized pulse shaping, beam pointing, and temporal phasing have demonstrated, through imaging of the Hohlraum and capsule dynamics, that a symmetric implosion using a 14-ns low-adiabat drive pulse {2× longer than high-density-carbon ablator designs using low gas-fill density Hohlraums [Divol et al., Phys. Plasmas 24, 056309 (2017)]} is possible in a low backscatter loss 0.45 mg/cc He-filled Hohlraum. The ingress of the Hohlraum walls was mitigated by revisiting the adiabat-shaped design [Clark et al., Phys. Plasmas 21, 112705 (2014)] that uses a low-power (1 TW) trough that delays the wall expansion. Low-mode P2 and P4 drive asymmetry swings caused by the drift of the laser spots were essentially zeroed out by employing temporal beam phasing between cones of beams [Turner et al., Phys. Plasmas 7, 333 (2000)]. The results also indicate an improved coupling efficiency of ∼30% compared to an earlier design using higher density filled Hohlraums and pave the way for revisiting low-adiabat, high convergence drives using CH ablators.

Advances in silicon photonics for high-capacity optical interconnects - INVITED

We review our recent progress on advanced silicon photonic devices and photonic circuits, including advanced grating couplers, modulators, mode and polarization division multiplexing and integrated optical signal processors for use in high capacity data center interconnects. The use of shifted polysilicon overlay gratings on waveguide grating couplers to improve coupling efficiency and polarization independence will be described. We also present our recent results on silicon microring and silicon-germanium electroabsorption modulators for 100Gbaud data transmission and their use polarization and mode division multiplexed optical fiber interconnects. We present novel integrated optical signal processors which can unscramble the mixing of polarization and mode data lanes that will occur after fiber transmission and demonstrate 400Gb/s per wavelength intensity modulation direct-detection silicon photonic transceivers.

3D Integrated Laser Attach Technology on a 300-mm Monolithic CMOS Silicon Photonics Platform

Enabling cost-effective and power-efficient laser source on a silicon photonics (SiPh) platform is a major goal that has been highly sought after. In the past two decades, tremendous effort has been made to develop various on-chip integration techniques to enhance SiPh circuits with efficient light-emitting materials. Here we review our recent advancements in hybrid flip-chip integration of III-V lasers on a 300-mm monolithic SiPh platform. By leveraging advanced complementary metal oxide semiconductor (CMOS) manufacturing processes, we have demonstrated wafer-scale laser attach based on a precisely controlled cavity formed on a silicon-on-insulator (SOI) substrate. The laser integration process is aided by precise mechanical alignment features on the SiPh wafer and high-precision fiducials on the laser. Efficient laser-to-SiPh-circuit butt-coupling with optical power up to 20mW was demonstrated through wafer- and module-level characterizations. Key performance metrics including side-mode suppression ratio, mode-hopping, and relative intensity noise were characterized after laser integration. In addition, early reliability assessments were performed on laser-attached SOI wafers and Si submount assemblies to understand the long-term performance stability of the lasers on the monolithic platform. To further enhance the performance of the laser-integrated chip, we explored alternative spot-size converters that could simultaneously enable improved coupling efficiency and relaxed fabrication tolerance, thus showing great promise over traditional designs.

Biosensing empowered by molecular identification: Advances in surface plasmon resonance techniques coupled with mass spectrometry and Raman spectroscopy

Surface plasmon resonance (SPR) has been utilized extensively in bioanalysis since the early 90s due to its unique combination of label-free, highly sensitive, and robust detection. In recent years, SPR has been coupled with and complimented by several other techniques that provide the qualitative and molecular information that SPR lacks. In this paper, advances in studies that present molecular identification to quantitative measurements by SPR are reviewed. In particular, coupling of SPR measurements and MALDI mass spectrometry (MALDI-MS) has been broadly explored where plasmon-assisted ionization upon gold substrates appears to demonstrate many added benefits. Imaging SPR analysis, upon coupling, has contributed to new analytical capability that proves to be powerful with elevated throughput. The combination of SPR and Raman spectroscopy has also found a wide range of applications in providing molecular information that promotes quantitative analysis. Similar to MALDI, the plasmonic thin-film metal substrates provide a desired surface structure and property for Raman enhancement, improving subsequent molecular recognition. Instrumentation advancements and improvements in coupling efficiency has facilitated a series of SPR sensor developments where the plasmonic properties of the surface contribute uniquely to the performance of the coupled technique.

Parabolic microlensed optical fiber for coupling efficiency improvement in single mode fiber

The efficiency of optical coupling between an optical fiber and other components be it a light source, a photodetector or another fiber, often depends on the performance of the focusing components. In optoelectronics, microlenses are generally incorporated at the end of optical fibers to ensure optimal coupling. These microlenses are primarily fabricated with a spherical profile easier to achieve, with a determined radius and at low production costs. However, these microlenses exhibit a relatively large waist due to intrinsic spherical aberrations making it difficult to couple light into single mode fibers. This paper presents the results of a study of a microlens having a parabolic profile that has been made of polydimethylsiloxane (PDMS) at a single mode optical fiber (SMF 9/125) end terminal. The contribution of the parabolic profile as compared to spherical shaped one is analyzed. Estimates at the wavelengths of primary importance, λ =1.310 µm and λ =1.550 µm, have shown a decrease in the spot radius diagram in the focal plane by 3, from an root mean square (RMS) value of 0.623 µm in the spherical case to less than 0.229 µm in the parabolic case. The measured optical coupling has improved to 98.5% under optimal conditions (without taking into account the bulk absorption and the effects of Fresnel reflection). For different studied microlens curvatures’ radii, the obtained waist values vary from 1.00 to 4.90 µm with working distances from 5.80 to 48.80 µm, respectively.

Modulating the Coupling Efficiency of P450 BM3 by Controlling Water Diffusion through Access Tunnel Engineering.

Cytochromes P450 have gained much interest for their broad substrate scope in the catalysis of oxidation reactions for pharmaceuticals, plastics, and hormones. However, achieving high coupling efficiency by the engineering of P450s is still a big challenge. The presence of extra water around the active site is deemed to be related to uncoupling. In this study, the access tunnels of P450 BM3 from Bacillus megaterium are engineered to control water access from bulk solvent to the active site. Nine residues located in tunnels are investigated by site‐saturation mutagenesis to reduce water diffusion, thereby improving the coupling efficiency. The recombined variant N319L/T411V/T436A shows improved coupling efficiency (from 31.2 % to 52.6 %). Tunnel polarity analysis and molecular dynamics simulation further indicate that reduced water molecules around the active site lead to higher coupling efficiency. Overall, this study provides valuable insight on improving coupling efficiency by controlling water diffusion through tunnel engineering.

Inhomogeneous defect distribution of triangular WS2 monolayer revealed by surface-enhanced and tip-enhanced Raman and photoluminescence spectroscopy

Confocal optical microscopy and tip-enhanced optical microscopy are applied to characterize the defect distributions in chemical vapor deposition-grown WS2 monolayer triangles qualitatively and quantitatively. The presence of defects in individual monolayer WS2 triangles is revealed with diffraction-limited spatial resolution in their photoluminescence (PL) images, from which the inhomogeneous defect density distribution is calculated, showing an inverse relationship to the PL intensity. The defect-related surface-enhanced Raman spectroscopy (SERS) effect is investigated by depositing a thin copper phthalocyanine layer (5nm) as the probe molecule on the monolayer WS2 triangles surface. Higher SERS enhancement effects are observed at the defect-rich areas. Furthermore, tip-enhanced optical measurements are performed, which can reveal morphologically defected areas invisible in the confocal optical measurements. Furthermore, the area with high defect density appears brighter than the low-defected area in the tip-enhanced optical measurements, which are different from the observation in the confocal optical measurements. The underlying reasons are attributed to the near-field enhancement of the defect exciton emission induced by the optically excited tip and to an improved coupling efficiency between the tip-generated near-field with the altered dipole moment orientation at the local defect.

Designing a high-efficiency coupling system to couple a hollow Gaussian beam into single-mode fiber.

The low efficiency of coupling a hollow Gaussian beam into single-mode fiber terribly decreases the transmission efficiency of an optical communication system. In this paper, a coupling system containing a shaping lens and a coupling lens is designed based on the vector theory of refraction. The simulation results show that our coupling system can improve coupling efficiency to 81.45%, and the efficiency can still reach 74.73% even though chamfering and other factors are considered. This paper may not only provide engineers with a more efficient coupling system but also provide designers with ideas of hollow-solid (or solid-hollow) beam shaping systems.

Relaxed Tolerance Low-Loss Adiabatic Si3N4 to Polymer Waveguide Coupler for Dense Interconnects

Despite significant advances in silicon photonics, optical packaging and interconnection of photonic integrated circuits constitutes a large portion of the associated manufacturing costs. Optical fibers are the dominant approach to optical interconnection. However, techniques that rely on fibers lack scalability, have low efficiency and show poor misalignment tolerance. Proposed alternative solutions using polymer waveguides have shown improved coupling efficiency, misalignment tolerance and scalability. Here we present the design, simulation and the experimental confirmation of an adiabatic silicon nitride taper to polymer waveguide coupler with only 0.52 dB of TE coupling loss at 1550-nm wavelength, excluding material loss. The coupler demonstrates $\pm 4~\mu \text{m}$ of lateral misalignment tolerance with a 1-dB penalty which, to the best of our knowledge, is the highest reported tolerance for silicon nitride to polymer waveguide coupling.

Coupling efficiency improvement of light source with a convex lens for space charge managements

Since Charge Management in space is mainly based on ultraviolet discharge technology, the ultraviolet light source system is one of the key devices of the charge management system, which significantly affects the performance of Charge Management. As reported recently, the coupling efficiency of the UV LED light source system is only about 13%. This paper analyzes the coupling types of UV LED light source system and establishes the LED-lens–fiber coupling model, next numerical simulations and experiments are carried out, finally the coupling efficiency of the UV light system is improved to 30%. Since improving the coupling efficiency can effectively reduce the power consumption and increase the useful life, the LED-lens–fiber coupling method has a strong prospect in space missions.

High precise time division multiplex UV pulse waveform measurement system for high power laser facility

In high power laser facility, the waveform measurement of UV pulse injected to target is very important for power balanced control and experiment result analysis. A time division multiplex UV frequency modulation pulse waveform measurement system based on fiber bundle and lens array is built for a high precise measurement result as well as low construction and maintaining cost. The system can remarkably improve coupling efficiency inject to fiber contribution to the aperture splicing sampling technology and a 50μm multi-mode UV fiber specially developed with 9.2GHz bandwidth@60m transmission. A “four-in-one” time division multiplex measurement system is built for laser facility and the practical experiment indicated that the system can realize precise waveform measurement within good economy and anti-interference performance.