Journal of Lightwave Technology

We demonstrate the first millimeter-wave Gb/s transmission of broadband wireless signals using uncooled directly modulated lasers to give a low-cost solution. Data signals to and from the base station are distributed at intermediate frequencies for reduced chromatic dispersion together with a remote 40-GHz local oscillator signal for frequency upconversion/downconversion. Coarse-wavelength-divisio... View full abstract»

We investigate the impact of state-complexity reduction on the performance of maximum likelihood sequence detection (MLSD) receivers for direct-photodetection long-haul optical communication systems affected by uncompensated chromatic dispersion (CD). We directly compare two possible approaches: (i) detection through a simple ldquobrute-forcerdquo state-complexity reduction strategy and (ii) a mor... View full abstract»

We consider an optical hybrid switch that can function as an optical burst switch and/or optical circuit switch. We propose and describe in detail a new implementation whereby circuits have nonpreemptive priority over bursts. To achieve nonpreemptive priority, during circuit setup time, if there exist bursts that use wavelength channels (also called links) required by the circuit, the circuit is a... View full abstract»

A coupler-type transverse electric/transverse magnetic (TE/TM) polarization splitter, in which a metal-loaded core is slightly widened, is analyzed using the three-dimensional beam-propagation method. Before analyzing the splitter with the slightly different core widths, the performance of a splitter with two identical cores is evaluated. The use of the two identical cores results in a high crosst... View full abstract»

We present an overview of our results on the design, material growth, device characterization, and spectroscopic applications of MOVPE-grown quantum cascade lasers (QCLs). These devices are capable of room-temperature (RT) continuous-wave operation and high power emission. The first section focuses on growth of laser material, device fabrication, and quantum design The second section discusses RT ... View full abstract»

The dependence of luminous efficacy on phosphor concentration and thickness for high-power white light-emitting-diode (WLED) lamps is investigated by employing three-dimensional ray-tracing simulations. The simulations show that the brightness or luminous efficacy of WLED lamps highly depends on the combination of phosphor concentration and phosphor thickness (or phosphor-matrix composite volume).... View full abstract»

The coupling between negative and positive index medium waveguides is investigated theoretically in this paper. A coupled mode theory is developed for such a waveguide system and its validity is verified. Interesting phenomena in the coupled waveguides are demonstrated, which occur in the case when the negative index medium waveguide in isolation guides its mode backward. A new type of coupled mod... View full abstract»

An improved version of a digital-to-analog converter (DAC) based on a multi-electrode Mach-Zehnder interferometer (MZI) is presented and analyzed. The device described has superior performance regarding both linearity and dynamic range. The improvements are achieved by utilizing a special mapping method between the analog input and the digital sequence applied to the device, and by an optimized se... View full abstract»

This paper provides some mathematical formulae for Risley beam steer control system that is used for free space optical interconnection system. Given the prisms' orientations, the analytic formulae can be used to calculate the pointing position. For the inverse problem, i.e., given the desired pointing position, the required prisms' orientations can be obtained efficiently by applying any numerica... View full abstract»

We present a multimode longitudinal pumping scheme for integrated rare-earth-doped waveguide amplifiers which allows an efficient use of low cost multimode pump sources. The scheme is based on evanescent pump light coupling from a multimode low loss waveguide to a single mode active core. Multimode pump light is gradually coupled to the active waveguide, which is single mode at the signal waveleng... View full abstract»

We present a new method for analyzing eye diagrams that always provides a unique solution by making use of a robust, least-median-of-squares (LMS) location estimator. In contrast to commonly used histogram techniques, the LMS procedure is insensitive to outliers and data distributions. Our motivation for developing this algorithm is to create an independent, benchmark method that is both amenable ... View full abstract»