When a piezoelectric element 3 applies an external force to a plastic photonic crystal, the photonic crystal deforms, and accordingly, the photonic band gap easily changes. When the photonic band gap changes, transmission of light with a specific wavelength is limited. Therefore, light with a desired...http://www.google.com.au/patents/US7088747?utm_source=gb-gplus-sharePatent US7088747 - Variable wavelength light source
