Photochemical modulation of alignment of liquid crystals and photonic applications

The recent highlights in the photoinduced modulation of the liquid-crystalline (LC) alignment and their applications to photonics are reviewed. The molecular alignment of LCs can be controlled by either the photochemical process or the photophysical process and we can change the birefringence as well as refractive index of the material by the modulation of the LC alignment. The photoresponsive LCs show very quick response to stimulus light: the response time is ∼200 ns. Furthermore, the extremely large refractive index modulation (Δn=∼10−1) can be also induced. The photoresponsive LCs, therefore, are potential materials for holographic recording and other photonic device.