According to the inherent requirements of education for talents' knowledge, quality and comprehensive ability and the major training goals of optoelectronics information science and engineering, in order to enhance the undergraduates' comprehensive practical ability and consciousness of innovation, we carried out the reforms of teaching method and teaching mode, which took the training programs of innovation and entrepreneurship for undergraduates, extracurricular academic research fund, "Chun-Tsung Scholar" program or research projects of their tutors as the guidance, and took the all levels of relevant discipline competitions as the promotion. And the training mainline of engineering innovation talents as "undergraduate's tutorial system →innovative training program or tutor’s research project →academic competition →graduation projects (thesis)" was constructed stage by stage by combining the undergraduates' graduation projects and their participated academic competition into one for improving the quality of the graduation projects (thesis). The practical results of the last several years illuminate that the proposed training model can effectively stimulate the students' awareness of autonomous learning, enhance their comprehensive ability of analyzing and solving problems and improve their ability of engineering practice and innovation as well as their teamwork spirit.
We investigate the group velocity of electromagnetic signals in compositionally graded films consisting of nonspherical particles. The theory is first based on generalized effective medium approximation to obtain the local dielectric function tensor in a <i>x</i> slice. Then, the effective dielectric tensor of the graded film is directly determined, and the group velocities for ordinary and extraordinary waves in the film are derived. It is found that the group velocity is dependent on the graded profile and the particles' shape. For a power-law graded profile <i>f</i>(<i>x</i>) = <i>ax<sup>m</sup></i>, increasing <i>m</i> results in the decreased extraordinary group velocity. Such a decreased tendency becomes significant when the incident angle increases. Moreover, enhanced or decreased group velocity may be achieved when the geometric shape of particles is non-spherical. In detail, oblate particles with large depolarization factor <i>L</i> results in large velocity enhancement and prolate one with small <i>L</i> leads to decreased velocity for normal incidence. Therefore, the non-spherical shape and graded profile play crucial roles in determining the magnitude of the group velocity in compositionally graded film.