Purdue University researchers have developed a new "plasma oxidation of the material," it is expected to bring ultrafast all-optical communications technology, at least compared with traditional approaches to 10 times faster. Related papers published in the near future, "optics" Journal of the Optical Society of America.

Optical communication with the laser pulse along the fiber to transmit information for telephone services, Internet and cable TV; and all-optical technology, whether the data stream or control signals are light pulses, without any electrical signal to control the system. First author, doctoral student Nathaniel Kinsey said data transfer, the amount of reflected light can be modulated is a necessary condition, "We can design a film so that the reflected light increases or decreases, the use of light reflection increased or decreased to encode the data, the change will result in changes in the reflected transmission. "

The researchers proved that aluminum-doped zinc oxide (AZO) to produce optical thin film material is modulated. They aluminum-doped zinc oxide, saturated with aluminum atoms in the zinc oxide to alter the optical properties of the material, so that it becomes like a metal at a specific wavelength, while at other wavelengths such as high resistance media.

AZO film refractive index close to zero, it can use the electron cloud-like surface plasmon to control the light. AZO pulsed laser will change the refractive index, thereby modulating the amount of reflected light. This material can work in the near infrared spectral range can be used in optical communications, and is compatible with complementary metal oxide semiconductor (CMOS).

The researchers assume that the use of this material to create a kind of "all-optical plasma modulator," or called optical transistors. In the electronic device, silicon is responsible for switching power transistor, the amplified signal. Optical transistor is a light rather than electricity to perform similar tasks, will greatly accelerate system operation.

This material is irradiated with a pulsed laser, the material of the electrons from one energy level (valence band) to move to a higher energy level (conduction band), leaving a hole, and finally re-combined with the holes. Transistor switching speed is limited by the completion of this cycle. In their AZO film, this period is about 350 femtoseconds, faster than the crystalline silicon about 5,000 times. This speed increase was transformed into the device, than traditional silicon-based electronic device at least 10 times faster.