Reduction of polarization loss of five-splitting by T-shaped arrays

Abstract

We present five-splitting equal-intensity laser output based on a T-shaped reflection grating under normal incidence, which is aimed to reduce polarization loss. Although five-splitting has been reported by a single-layer grating, a set of parameters can only be effective for either TE or TM polarization. Both TE and TM polarizations can be operated simultaneously by T-shaped arrays. For only one set of groove profiles, splitting efficiencies of 18.26%/19.32%/18.53% and 18.34%/18.25%/19.56% can be reached in ±2nd / ± 1st / 0th orders for TE and TM polarizations, respectively. Within the incident wavelength of 1544 to 1552 nm and the incident angle range of 0 deg to 0.19 deg, each reflective efficiency for a five-splitting laser output is >17 % . The diffraction mechanism inside the grating can be explained by the modal method. The polarization-independent T-shaped grating with five-splitting laser output presented here should be useful in various laser fields due to good manufacturing tolerance and incident performance.