Ultracompact polarization converter with a dual subwavelength trench built in a silicon-on-insulator waveguide

• Published in: Optics letters Vol. 37; no. 3; p. 365
• Main Authors: Velasco, Aitor V, Calvo, María L, Cheben, Pavel, Ortega-Moñux, Alejandro, Schmid, Jens H, Ramos, Carlos Alonso, Fernandez, Iñigo Molina, Lapointe, Jean, Vachon, Martin, Janz, Siegfried, Xu, Dan-Xia
• Format: Journal Article
• Language: English
• Published: United States 01.02.2012
• Subjects: Optical Phenomena; Rotation; Silicon
• ISSN: 1539-4794
• DOI: 10.1364/OL.37.000365

The design and fabrication of an ultracompact silicon-on-insulator polarization converter is reported. The polarization conversion with an extinction ratio of 16 dB is achieved for a conversion length of only 10 μm. Polarization rotation is achieved by inducing a vertical asymmetry by forming in the waveguide core two subwavelength trenches of different depths. By taking advantage of the calibrated reactive ion etch lag, the two depths are implemented using a single mask and etching process. The measured converter loss is -0.7 dB and the 3 dB bandwidth is 26 nm.