Hi damian,
http://ieeexplore.ieee.org/xpl/articleDetails.jsp?tp=&arnumber=6081949&queryText%3DSurface+Plasmon+Antenna+with+Gold+Line+and+Space+Grating+for+Enhanced+Visible+Light+Detection+by+a+Silicon-on-Insulator+Metal%E2%80%93Oxide%E2%80%93Semiconductor+Photodiode
this is the link for my earlier question.