Diamond revolutionizes optomechanics

For the first time, researchers have managed to use polycristalline diamond to manufacture an optical circuit.



Two parallel free-standing waveguides made of polycrystalline diamond serve as mechanical resonators. Electromagnetic waves propagate inside of them.

Diamond has special physical characteristics: due to the high bond energy of the carbon atoms, diamond possesses a large bandgap and high thermal conductivity. In addition, it is mechanically and chemically stable. Little absorption in the visible range of the optical spectrum enables high transmission of photons even through thick layers. This makes diamond an ideal candidate for optomechanical applications.

A group of researchers has made use of the special characteristics of diamond in the development of an optical circuit. For the first time, they have managed to work with polycristalline diamond. So far, optical circuits have been manufactured using monocrystalline diamond substrates, which - due to their high level of purity - are difficult to manufacture and challenging to process. In contrast, polycristalline diamond consists of numerous small diamond crystals, which makes them easier to manufacture in larger sizes and process industrially. "We have optimized the deposition of artificial diamond in a way so that we can use standard technology processes. This makes processing easier, which in turn reduces production cost - new applications become possible" explains Dr. Christoph Nebel of the Fraunhofer Institute for Applied Solid State Physics IAF in Freiburg. Together with the company Diamond Materials in Freiburg, Fraunhofer IAF manufactures high quality nano- and polycrystalline CVD diamond layers. Researchers of the Karlsruhe Institute for Technology KIT were able to develop the optomechanical circuit on this basis.

New sensor technology thanks to diamond

Optomechanics combines integrated optics with mechanical elements. The researchers used nanomechanical diamond resonators for their circuit, which impress with high quality and sensitivity. In the future, this will enable sensor platforms which are completely optically controlled. Using diamond has made it possible "to manufacture all components of a ready-to-use optomechanical circuit monolithically" says Wolfram Pernice of KIT. Integrated optics works in a similar manner to integrated electrical circuits. Whereas optical circuits transmit information via photons, conventional electronic circuits transfer data via electrons.  Integrated optics aims to combine all components required for optical communication in an integrated optical circuit.

However, diamond is not only an ideal material basis for optical circuits. By integrating photonic centers it is possible to realize "single photon emitters", which serve as a light source for the photonic structures. Other applications can be found in the area of electrochemical sensors, which can help monitor water and food quality. Moreover, when integrated into bioanalytic systems they can help diagnose cancer early.


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