One of the three co-laureates of this year's Nobel Prize in physics said he fled Japan for the United States because of the stifling environment for entrepreneurs in his native country.

Speaking in Santa Barbara, California on Tuesday, 60-year-old materials scientist Shuji Nakamura said what had encouraged him in his work was "anger."

The professor at the College of Engineering at the University of California, Santa Barbara, cited two protracted legal disputes with his former employer, Tokushima Prefecture-based Nichia Chemicals.