Polarization-dependent tuning of Bragg reflection enabled through tilted subwavelength grating waveguide Bragg gratings.

We propose and demonstrate experimentally tilted subwavelength grating (SWG) waveguide Bragg gratings (WBGs). By tilting the SWG segments and optimizing the duty cycle, we can achieve polarization-dependent tuning of the spectral response of the SWG WBG, namely, the spectral response of the fundamental transverse electric (TE) mode shifts toward shorter wavelengths, while that for the transverse magnetic (TM) mode remains almost unchanged. In particular, for tilting angles of 5° and 30°, we can obtain a blueshift in the Bragg wavelength of 7 and 35 nm for the TE mode, while the Bragg wavelength for the TM mode remains within 0.5 nm. The proposed tilted SWG WBGs provide a novel method to manage polarization and/or obtain polarization-dependent wavelength selectivity with integrated WBG devices.