Highly efficient unibond silicon-on-insulator blazed grating couplers

In this letter, we report, design and fabrication of good asymmetrical Si-blazed gratings with a pitch of 383 nm, fabricated in unibond silicon-on-insulator using angled ion-beam etching. An output efficiency of 84% was achieved. The devices allow efficient coupling to/from small waveguides, of the order of 1 μm in height.