Wide-band two-port polarization-independent beam splitter based on an encapsulated transmission grating

A wide-band two-port polarization-independent beam splitter is designed and analyzed at the incident wavelength of 1550nm. Diffraction efficiencies are 49.67%/49.57% and 48.69%/48.88% for TE and TM polarizations in the 0th and the -1st, respectively. Usually, it's difficult for two-port beam splitter to achieve wide bandwidth for both polarizations. In this paper, the presented grating has advantages of wide incident wavelength range of 110nm and angular bandwidth of 8.8 degrees with good splitting ratio uniformity for both polarizations, particularly TE polarization. Moreover, the aspect ratio of the grating depth to the ridge width is low, which can be etched relatively easily and effectively. This wide-band splitter should be highly interesting for practical applications.