High-performance all-silicon polarizer with 415 nm bandwidth
Weixi Liu, Daoxin Dai, Yaocheng Shi
Abstract
On-chip silicon polarizers have been widely used in polarization controllers. However, there is limited research on all-silicon polarizer covering the whole optical communication band due to the strong waveguide dispersion for silicon waveguides. In this Letter, we demonstrated an all-silicon TE polarizer with high polarization extinction ratio and low insertion loss, working for the whole optical communication band. The device is based on a shallow-etched waveguide realized on a silicon-on-insulator (SOI) platform. The optical field of TE polarization is designed to be tightly confined in the shallow-etched silicon waveguide, while that of TM polarization is weakly confined. As a result, TE polarization propagates through the waveguide with low loss, while TM polarization leaks into the substrate and decays finally. The measurements show that a maximum insertion loss <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo><</mml:mo> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>0.25</mml:mn> </mml:mrow> <mml:mspace width="thickmathspace"/> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">d</mml:mi> <mml:mi mathvariant="normal">B</mml:mi> </mml:mrow> </mml:mrow> </mml:math> and polarization extinction ratio <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mo stretchy="false">(</mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">P</mml:mi> <mml:mi mathvariant="normal">E</mml:mi> <mml:mi mathvariant="normal">R</mml:mi> </mml:mrow> </mml:mrow> <mml:mo stretchy="false">)</mml:mo> <mml:mo>></mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>20</mml:mn> </mml:mrow> </mml:mrow> <mml:mspace width="thickmathspace"/> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">d</mml:mi> <mml:mi mathvariant="normal">B</mml:mi> </mml:mrow> </mml:mrow> </mml:math> over an ultrabroad operation band from 1260–1675 nm have been achieved for the proposed polarizer.