Papers by Keyword: Coupling Efficiency

Abstract: The modulation mechanism of the optical fiber phase sensor with ZnO coating is analyzed intensively in this paper. An extensive particle swarm ant colony algorithm and ant colony algorithm are used to optimize the power coupling efficiency of the sensor. The influences of the optimized device parameters on the power coupling efficiency are also investigated.

Abstract: Based on theoretical analysis, the beam expender used in all fiber lidar with a coupling efficiency of single mode fiber (SMF) is investigated. Some numerical computations are carried out and following results are obtained. For all fiber lidar in order to get the maximum coupling efficiency on SMF, the relationship between the distance d, ranged from the secondary to primary lens of the beam expender, and the laser waist spot location l, which is at a distance from the secondary lens of beam expender are obtained. And also the relationship between l and the measurable bandwidth is analyzed. Under the condition that if the laser location is certain and the imagine spot location is infinite, with adjusting the distance d which can make the image spot size obtain its minimum, the maximum coupling efficiency about 70.6% is got and the adjusting range of d has only 0.2~0.9mm. Assuming that the image spot distance is infinite, and the minimum of spot radius is got after the laser waist spot goes through the beam expender, the function between d and l is retrieved by use of laser propagation theory. By comparing the theoretical curve with the computing one, the theoretical function agrees with the numerical computing curve approximately. These conclusions have the important directive significance for design of all fiber Lidar.

Abstract: ICCD is one of the opto-electronic image sensors, commonly used in neutron low-light-level imaging system and the coupling of CCD and Image-Intensifier is the key technology in ICCD. This paper discussed the structure of ICCD, and simulated the coupling of relay lens, cone fibers and grin lens based on ZEMAX. We analyzed and checked their parameters such as geometric image, MTF, coupling efficiency, etc. Experimental results show that: The coupling of relay lens has high image quality; the coupling of cone fibers has high coupling efficiency; the performance of grin lens falls in between.

Abstract: In this paper, we investigate theoretically the coupling characteristics of two identical microfibers or nanofibers (MNFs) with different ambient refractive indices. The results show that, compared with weakly coupled waveguides, coupled two MNFs can provide a much smaller coupling length without sacrificing high coupling efficiency. This feature is helpful for studying and developing microphotonic or nanophotonic devices with MNFs.

Abstract: The paper proposes the simulation of aspheric lensed fiber for efficient coupling between laser diode and single-mode aspheric lensed fiber, which is applying SIMULINK in MATLAB with the theory of ABCD Matrix.

Abstract: Thin film based passive optical components assembled with a stainless steel tube via soldering is investigated under a packaging procedure. Finite element analysis is utilized to simulate the packaging procedure in the present study. Mismatch of the coefficient of thermal expansion among various components could induce residual stress over the assembly structure. Coupled thermal-elastoplastic analysis is adopted to predict the plastic deformation of the structure under the solidification process of solder joints. This post-solder-deformation could deteriorate the associated coupling efficiency due to the mis-alignment of the optical fibers. Temperature-dependent mechanical properties of the solder joint are employed in the simulations. Both two-dimensional plane strain and three-dimensional solid models are implemented into the analysis for comparisons. In order to improve the fiber alignment, and thus the coupling efficiency, a three-point bending device is externally loaded on the structure. Unloading procedure is subsequently performed to evaluate the ultimate deformed shape of the structure. Measurements of the insertion loss will be conducted using a power meter in the near future, while a correlation between the coupling efficiency and the fiber alignment can then be expected.

Abstract: An InGaAsP/InP Electroabsorption Modulator (EAM) with single-sided large optical cavity (LOC) was studied and fabricated by low-pressure Metal Organic Chemical Vapor Deposition (MOCVD). Results show that the optical profile of EAM is greatly improved by the LOC structure, which is expected to increase the coupling efficiency and the optical saturation power.

Abstract: In this paper we have proposed a photonic crystal structure to enhance the coupling efficiency between photonic crystal waveguide (PCW) and the conventional dielectric waveguide. The proposed waveguide characterized with employing the taper structure and varying the holes’ radius in the taper. Two-dimensional (2D) finite-difference time-domain (FDTD) method has been used to analyze the structure. The simulation results show that the coupling efficiency can be achieved as high as 81.6% at the wavelength of 1.55um.