Numerical analysis of DFB lasers with uniform longitudinal-intensity distributions using the modified time-domain traveling-wave algorithm

Abstract

Using the modified time-domain traveling-wave algorithm, we investigate DFB lasers with uniform longitudinal-intensity distributions. It is shown that a uniform longitudinal-intensity distribution is effectively obtained by a combination of adding multiple phase shifts and varying coupling coefficients along the longitudinal direction.ABSTRACT: Recently, in order to satisfy the demand for precise and reliable global positioning system (GPS) applications, the dual-band circularly polarized (CP) antenna has been developed. This paper describes a new design of a probe-fed dual-band CP microstrip antenna with two corner-truncated square patches that overlap without an air gap. Compared with the conventional dual-band CP antenna with an air-gap layer between the two patches, the volume of this antenna is reduced and its fabrication is easier. Details of the proposed antenna design and experimental results are presented and discussed. The measured results confirm the validity of this design, which can meet the requirement of GPS application at 1575/1227-MHz frequencies.