Search

To mitigate potential interferences with coexisting wireless systems operating over 3.3–3.6 GHz, 5.15–5.35 GHz, or 5.725–5.825 GHz bands, four novel band-notched antennas suitable for ultra-wideband (UWB) applications are proposed. These include UWB antennas with a single wide notched band, a single narrow notched band, dual notched bands, and triple notched bands. Each antenna comprises a half-circle shaped patch with an open rectangular slot and a half-circle shaped ground plane. Good band-notched performance is achieved by using high permittivity and low dielectric loss substrate, and inserting quarter-wavelength horizontal/vertical stubs or alternatively embedding quarter-wavelength open-ended slots within the feed line. The results of both simulation and measurement confirm that the gain suppression of the single and multiple band-notched antennas in each desired notched band are over 15 dB and 10 dB , respectively. The radiation pattern of the proposed triple band-notched design is relatively stable across the operating frequency band. [ABSTRACT FROM PUBLISHER]

We present a new distributed time domain model (DTDM) for use in complex laser modeling. Like several other models, we use Maxwell's wave equations, but with a time dependent polarization in the form of classical electron oscillators (CEO). It is based on the neoclassical rate equations of A. E. Siegman. The unique feature of our model is the use of a virtual electric field used to simulate random spontaneous emission. This approach has not been used before. The model includes effects such as gain suppression, optically induced gratings, and excess noise. We discuss our results and compare and contrast them with other published work. [ABSTRACT FROM PUBLISHER]

We observed experimentally four-wave mixing (FWM) between a 14xx-nm pump and a 15xx-nm signal in a forward-pumped distributed Raman amplifier (DRA) over 50 km of nonzero dispersion-shifted fiber with a zero dispersion wavelength of 1497 nm. The 100-mW pump Fabry-Perot (FP) spectra centered at 1440, 1450, and 1460 nm are reproduced via FWM around the single-wavelength probe signal around 1558, 1548, and 1538 nm, respectively. The suppression of DRA gain by about 2-3 dB was experimentally observed with peak FWM at minimum phase mismatching between two 14xx-nm FP pump wavelengths and two 15xx-nm signal wavelengths. This DRA gain suppression, together with the reproduced pump FP spectrum at 15xx-nm signal band, may limit the usefulness of the forward-pumped DRA, generating spectrally nonuniform FWM-induced noise floors and crosstalk in wavelength-division-multiplexed fiber-optic transmission systems. [ABSTRACT FROM PUBLISHER]