J. M. Xu

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—We propose a new concept of binary superimposed gratings (BSG's) as multiwavelength grating reflectors and show it as an effective structural improvement over the existing designs, to both the fabrication process and device performance. We also present a study of key design issues for widely tunable lasers based on grating mirrors with a comb-like(More)
— We employ two-dimensional (2-D) self-consistent physical modeling of a particularly promising lateral current injection laser reported recently in the literature to gain insight into the physical mechanisms governing the operation of this family of devices. We demonstrate the substantial benefits to be obtained from improved hole injection facilitated by(More)
We present a study of the first silicon microdisk resonators which are smaller than the free-space resonant wavelength in all spatial dimensions. Spectral details of whispering gallery modes with azimuthal mode number m = 4-7 are measured in microdisks with diameters between 1.35 and 1.89microm and are studied at wavelengths from 1.52 to 1.62microm. For the(More)
The authors propose a new approach to THz power generation: the " nanoklystron. " Utilizing silicon micromachining techniques, the design and fabrication concept of a mono-lithic THz vacuum-tube reflex-klystron source is described. The nanoklystron employs a separately fabricated cathode structure composed of densely packed carbon nanotube field emitters(More)
Typically the disorder that alters the interference of particle waves to produce Anderson localization is potential scattering from randomly placed impurities. Here we show that disorder in the form of random gauge fields that act directly on particle phases can also drive localization. We present evidence of a superfluid bose glass to insulator transition(More)
Spatially tiled architectures such as CGRAs are robust architectural choices for accelerating applications in the DSP, scientific computing, and embedded domains. In the embedded application domain in particular, CGRAs offer a low power alternative to FPGAs by providing coarse-grained word-level computation resources as opposed to FPGAs' fine-grained(More)
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