Imai Tadayuki, Yagi Shogo, Toyoda Seiji, Miyazu Jun, Naganuma Kazunori, Kawamura Sohan, Sasaura Masahiro, Fujiura Kazuo
NTT Photonics Laboratories, Nippon Telegraph and Telephone Corporation, Atsugi, Kanagawa, Japan.
Appl Opt. 2012 Apr 1;51(10):1532-9. doi: 10.1364/AO.51.001532.
We fabricated cylindrical varifocal lenses with fast responses by using the strong Kerr effect of KTa(1-x)Nb(x)O(3) (KTN) single crystals. We observed focus shifts of up to 87 mm with the assistance of a 250 mm focal length lens, which corresponds to a focus shift from infinity to 720 mm by the KTN lens itself. The response time was as fast as 1 μs. We also present a simulation method for calculating refractive index distributions in KTN single crystals, which is essential when designing the lens. The method is characterized by the strain contribution, which has not conventionally been typical of electro-optic simulations. We used this method to explain the refractive index modulations that are characteristic of the varifocal lenses.
