Fiber optics, almost one mm in diameter, hollow, filled with helium can conduct enough infrared laser power to eliminate the need for spark plugs:
http://appft1.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.html&r=1&f=G&l=50&s1=%2220060055925%22.PGNR.&OS=DN/20060055925&RS=DN/20060055925
Sorry about the long link.