Piper Jaffray analyst Troy Jensen says he's turning more upbeat on the optical group on the anticipation that demand trends should improve in the second half of 2018 and the upcoming 400G cycle should provide a tailwind for growth in 2019 and beyond. While the core optical sector has been struggling for the past five quarters, growth rates have bottomed, estimates have been reduced and better times should be facing the industry in the second half of the year, Jensen tells investors in a research note. His favorite stocks in the space are Lumentum (LITE), II-VI (IIVI) and Fabrinet (FN).