All-optical thin-film switch yields 20-ns response times

All-optical thin-film switch yields 20-ns response times

Kyoichi Sasaki and Toshihiko Nagamura at Shizuoka University (Hamamatsu, Japan) have devised an all-optical switch that may ultimately prove useful in ultrafast data processing. The researchers report 20-ns response times in the switching device based on changes in the complex refractive index of a sandwich of silver and polymer thin films containing photochromic dye.

Sasaki and Nagamura used the device to control the reflection of a probe beam, provided by a tunable HeNe laser at 543 nm, from the silver surface of the thin films. The reflection was turned on and off on the opposite polymer surface by 8-ns, 1-2.5-mJ pulses from a Nd:YAG laser at 355 nm and 8-ns, 6-mJ pulses from an OPO producing 600 nm, respectively. The researchers reported a tenfold difference in reflectance between the on and off states, which could be maintained without applied power. They also believe that the all-optical nature of the switching should provide picosecond response times.