We demonstrate fully-etched fiber-waveguide grating couplers with sub-wavelength gratings showing high coupling efficiency as well as low back reflections for both transverse electric (TE) and transverse magnetic (TM) modes. The power reflection coefficients for the TE and TM modes have been significantly suppressed to -16.2 dB and -20.8 dB, respectively. Focusing grating lines have also been u...

We report on the design and fabrication of compact and potentially low-cost multimode fiber matched 1 x N and N x N couplers for LAN’s. The design utilizes the self-imaging effect and tapering of the Multi-Mode Interference (MMI) section. An extended mode propagation analysis and 3-D beam propagation method (BPM) were used to analyze and design these structures. The simulations show that the co...

An interferometric model is proposed to estimate the phase differences in lossless, strongly coupled biconical fiber couplers. This approximate method is simpler than the traditional s-parameter network theory-based analysis technique and minimizes the number of unknowns. The phase difference between the transmitted and coupled light fields is directly related to the field interaction and can b...

Analytical expressions are derived which relate the optical bandwidth and the fabrication tolerances of multimode interference (MMI) couplers to their most important design parameters. These expressions compare adequately with mode analysis simulations. For strong guided structures, the optical bandwidth is shown to be inversely proportional to the number of input and output ports N and to the ...

This paper describes the design and testing of a feed network for a transparent flat plate array antenna. This antenna is the top of a stack of three antennas that must occupy the same volume while pointing in different directions. At many pointing angles, the antenna will create blockage for the antennas underneath. In order to minimize the blockage, the array and its transmission lines must b...

Recent experience with X-band accelerator structure development has shown the rf input coupler to be the region most prone to rf breakdown and degradation, effectively limiting the operating gradient. A major factor in this appears to be high magnetic fields at the sharp edges of the coupling irises. As a first response to this problem, couplers with rounded and thickened iris horns have been e...

A family of self-aligning micromachined fluidic couplers are presented here. Bulk micromachined and DRIE processed silicon structures have been investigated as a means of providing external connections via fused silica capillaries for MEMS fluidic devices. These couplings can have arbitrary geometry, ensuring compatibility with most fluidic ports. In addition, performance exceeds typical requir...