A New Photodetector Introduced of Size Less than One Millionth of a Square Millimetre

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Data traffic is expanding globally. Cables based on glass-fibre transfer data over distances at a frequency of light. Once they reach their final point, these optical frequencies have to be transformed into electronic signals for further processing in a computer. Scientists have now introduced a new form of photodetector that required much less space than traditional ones. The device has a base dimension less than one millionth of a square millimetre without information transmission rate being altered greatly.

The newly introduced photodetectors, the tiniest photodetectors globally for optical data transmission, can be utilized for unified optical circuits that imperatively boost the functional performance of interactive optical systems. Due to less space required, numerous detectors can be organized on optical chips. In studies, the scientists reached a rate of data of up to 40 gigabits per second.

“Such component can transfer the elements of a complete DVD within a fraction of a time,” says expert physicist Sascha Muhlbrandt of KIT. He carried on his research at the Institute of Microstructure Technology and the Institute of Quantum and Photonics Electronics of KIT. The rate can be further enhanced. “It is till date the tiniest detectors reaching to such rate. It is one hundred times tinier than a traditional photodetector,” says Muhlbrandt. The fast speed photodetector, called PIPED, Plasmonic Internal Photoemission Detector is now introduced by Muhlbrandt.

A special benefit of the diminished size is that the photodetector can be incorporated with electrical components on the same CMOS based chip. “Introduction of new plasmonic elements for fast-speed transfer of data between electrical chips in the computer links the benefits of optical and electrical components, while the transfer rate is comparable or even enhanced,” says project associate Professor Manfred Kohl of Institute of Microstructure Technology, KIT.

The phototdetector was introduced under the NAVOLCHI project. Under the seventh EU Research Framework Programme, the three years project based on KIT duration in the field of communication and information technologies was funded with around EUR 500,000.

The great performing photodetector utilizes so-called surface plasmon polaritons, greatly concentrated electromagnetic waves at interfaces based on metallic-dielectric, to link electrical and optics on tiniest space. “This novel section of plasmonic transceivers is grounded on the mechanism creating photocurrent that is direct signal transfer at metallic interfaces with optical frequencies. The procedure is known as internal photoemission.  For augmenting the efficacy of light absorption as well as light conversion into electronic signals, charge carriers are prepared at a titanium-silicon transition and opted for another gold-silicon transition.

The boosted rate is due to the special detector geometry. Both silicon-metal transitions are placed less than one hundred billionths of a meter across.

The scientists consider the concept of PIPED to be necessary not only for further optical data transmission systems but also for wireless data transferring. “Such new approach to identifying optical symptoms enable the creation and identification of electromagnetic signals with bandwidths in a range of terahertz,” says lecturer Christian Koos of KIT. “Plasmonic elements might be useful in rapid wireless communication and enable for transmission rated of up to 1 terabit per second,” says Muhlbrandt.