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We report our advances in development of subwavelength engineered metamaterial structures in silicon waveguides, specifically high-efficiency fiber-chip couplers, ultra-broadband surface grating couplers and nanophotonic beam splitters, evanescent field waveguide sensors and on-chip Fourier-transform spectrometers.
Subwavelength engineering in silicon photonic integrated circuits is a powerful design tool that allows one to synthesize an effective photonic medium with adjustable refractive index. This creates a new degree of freedom in photonic circuit design. We present an overview of the fundamental concept and its application to address several important practical challenges in the implementation of silicon...
Subwavelength grating structures with a pitch smaller than the Bragg resonance length can be used for engineering the refractive index in silicon photonic waveguides. We discuss the principles, design, fabrication and applications of subwavelength nanostructures in silicon photonics and review our recent results on fiber-chip coupling structures, surface grating couplers, waveguide crossings, and...
We present hermetically encapsulated, mechanically coupled, 20 MHz breathe-mode ring filters with ultra narrow bandwidths of 5.9 kHz and 8.9 kHz, which correspond to 0.029% and 0.044% bandwidth with less than 2.7 dB insertion loss. This is the narrowest percent bandwidth achieved by a mechanically coupled MEMS filter. The ability to attain an insertion loss this small for such a small percent bandwidth...
The rapid development of electronic equipment makes the study on electromechanical coupling problem (EMCP) a new research area. The electromechanical coupling analysis is a multidisciplinary problem mainly involving the structure, electromagnetics and thermology. To begin with, the methods of calculating three fields are presented involved in EMCP, which is followed by the coupling relation. Then,...
The additional estimation error introduced by the use of finite ground planes is evaluated numerically for two types of conventional direction finding (DF) systems. The analysis reveals that commonly accepted ground plane dimensions result in degraded estimation accuracy when the incoming signals are of unknown polarization.
Tactical ground-based electronic warfare systems have conflicting requirements for wide frequency coverage, good sensitivity and direction finding accuracy, and small size and weight. An experimental multi-band direction finding (DF) antenna was developed to investigate the feasibility of constructing a compact lightweight antenna array by superposing three sub-arrays in the same plane. Experimental...
Direction finding (DF) techniques based on a circular array of monopoles or dipoles have the advantage of being able to provide unambiguous direction of arrival (DOA) estimates over 360 degrees. Of the various implementation approaches that are possible, the Adcock direction finder (ADF) is commonly used at UHF and lower frequency ranges. One of the physical constraints is that the diameter of the...
An extremely high power, second harmonic TE21 gyrotron traveling wave amplifier (gyro-TWT) utilizing a MIG beam will be described. Based on a marginal stability procedure [1], a second harmonic gyro-TWT using a 100 kV, 25 A MIG beam with α = 1 and Δvz/vz = 5% has been designed, where the total interaction tube is comprised of three sections separated by absorbing severs. The length of each section...
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