Experimental study of the self‐imaging phenomenon with weak‐guiding condition

Abstract

patterns in this case. By investigating the change of the antenna's performance, such as the impedance bandwidth, radiation patterns, and gains, due to the laptop housing, the design procedure of laptop antennas in a real situation can be further simplified. These structural features and electrical properties are very attractive for WLAN applications.ABSTRACT: This paper investigates a self-imaging phenomenon in a multimode interference (MMI) coupler. In the experiment, different selfimages which are undefined in MMI theory are observed. This undefined self-image is named the "pseudo-self-image " (PSI) as a matter of convenience. The characteristics of both the single self-image (0-dB selfimage: 0-dB SI), which is defined in MMI theory, and the PSI are compared and analyzed through simulation and experimentation to estimate the applicability of the PSI. Results show that the PSI has an imaging period the same as the 0-dB SI, and the excess loss and the extinction ratio of the PSI improve more than those of the 0-dB SI as the imaging period increases. ABSTRACT: A new technique for inducing relative group delays between the orthogonal transversal propagation modes in a single mode fiber is presented. It is based on a tunable linear chirp induced in aBragg grating written in a highly birefringent fiber by thermal means. The method can induce a relative delay over a wide range, making it possible for use in a polarization mode dispersion compensator.