Polycrystalline diamond fabrication of wafer-based optomechanical circuits

Diamond is optically transparent over a wide range of light wavelengths, including the visible spectrum from 400 to 750 nm. Because of this feature, it can be used specifically as an optomechanical circuit element in applications such as sensor technology, fluorescence imaging, optical biometry, etc. The manufactured components, ie resonators, circuits and chips, are of high quality and very popular.

To make full use of photons in the circuit, materials need to have specific optical and mechanical properties. Recently, scientists have realized the fabrication of optical circuits on single-crystal diamond substrates (high-purity crystals with no more than one impurity atom in every 100 million diamond atoms). Such loops are necessarily small and, therefore, their application in optical systems requires advanced fabrication methods.

A research experiment using polycrystalline diamond made of two parallel independent waveguides as a mechanical resonator, within which a light field (indicated in red/blue) can be observed propagating

Now, for the first time, researchers have achieved the fabrication of wafer-based optomechanical circuits using polycrystalline diamond. These vibratory systems are capable of responding to specific frequencies that excite the resonator into a vibratory state.

Although the crystal structure of polycrystalline diamond is more irregular, it is strong enough and easy to process. These special properties make polycrystalline diamond more widely used than single crystal materials. Polycrystalline diamond transports photons almost as efficiently as single-crystal substrate materials and is more suitable for industrial use.

“Nanomechanical resonators are currently the most sensitive sensors for a variety of precision measurements. However, it is extremely difficult to handle these smallest components with conventional measurement methods. In our study, This takes full advantage of the fact that it is currently possible to fabricate nanophotonic components of the same size as nanomechanical resonators. When the resonator responds, the corresponding optical signal can be transmitted directly into the loop.”