is 1.26 W, where the wavelength resolution of OSA was set to 0.01 nm. The spectrum is flat and the spectrum fluctuation is less than Ϯ1.5 dB in bandwidth of 80 nm in the region from 1510 nm to 1590 nm, except that at the wavelength around 1550 nm, a pump component was residual, which was 5 dB higher than the SC spectrum.As we magnified the horizontal axis of the Figure, the structure of the 10 GHz spacing optical multicarrier becomes clear. The optical frequency chain spectra around 1520 and 1560 nm are shown in Figures 4(a) and 4(b), respectively. Over 1000 channel optical frequency chain with 10 GHz spacing can be sliced from the spectrum, and the power level of each channel can be easily equilibrated due to the flat SC spectrum. This type of source may be useful in applications such as WDM-based optical communications, wavelength converter, and WDM radio-on-fiber (ROF) systems.
CONCLUSIONEfficient and symmetric SC generation was achieved by using a dispersion-flattened MF with small normal dispersion. Flat and broadband optical spectrum with spectral width of over 80 nm was obtained from 80-m long MF and a10-GHz optical frequency chain, generated with over 1000 channels from a single SC source. It is expected that the SC source can be applied for WDM transmission systems and the generated optical frequency grids can also be applied to ROF systems. In recent years, there has been a continuing interest in the investigation of compact, efficient and wide impedance bandwidth antenna in satellite and wireless communication applications. A microstrip antenna is an ideal choice for communication purpose, but the major drawback of microstrip antenna is the innate narrow bandwidth. The narrow bandwidth of antenna is a major obstacle that restricts wider applications. Additionally, conductor and dielectric losses could be significant at millimeter-wave frequencies, which degrade the efficiency and adversely affect the performance of the system. A dielectric resonator antenna (DRA) fabricated from low-loss and high-permittivity microwave dielectric material has been widely used to implement microwave components. The resonant frequency of which is predominantly a function of size, shape, and material permittivity [1]. DRA were first proposed by Long, McAllister, and Shen in the early 1980s [2]. Since then, the DRA has been widely studied because they offer a number of advantages such as small size, lightweight, low cost, high radiation efficiency, and ease of excitation [3]. Additionally, DRA avoid some limitations of the patch antennas including the high-conductor losses at millimeter-wave frequencies, and sensitivity to tolerances, and provide different radiation patterns based on various modes of operation [4].
ACKNOWLEDGMENTSThe most common method of feeding is coaxial probe feed, microstrip feed, aperture-coupled feed and coplanar-waveguide feed. Among these excitation schemes, aperture coupling is most frequently used because of ease of fabrication, compatibility with MMIC, and offers isolation between the microstri...
