The polarization rotation of an optical slot structure from the vertical to the horizontal direction, or vice versa, is demonstrated theoretically within an ultrashort conversion length. Based on mode-evolution theory and three-dimensional finite-difference time-domain simulation, two parallel nonlinearly tapered crossings are introduced and optimized in the transition region, which efficiently decreases the conversion length from 11 to 5 μm for the wavelength of 1.55 μm in a silicon-on-isolator system. More importantly, the extinction ratio of 22 dB and loss of 0.12 dB are numerically obtained using practical material parameters. The method and result presented here may be extremely valuable for the applications of integrated slot structures.
© 2013 Optical Society of America
Original Manuscript: March 27, 2013
Revised Manuscript: May 7, 2013
Manuscript Accepted: May 7, 2013
Published: May 31, 2013
Guoqiang Chen, Lixue Chen, Weiqiang Ding, Fangkui Sun, and Rui Feng, "Ultrashort slot polarization rotator with double paralleled nonlinear geometry slot crossings," Opt. Lett. 38, 1984-1986 (2013)