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Photonic and Optomechanical Sensors for Nanoscaled and Quantum Thermometry

WP1

Design and fabrication of photonic and quantum optomechanical devices

 

This work package is at the core of the project PhotOQuanT by working on the design and the fabrication of resonators necessary for the implementations of experiments envisioned in WP3 and WP4. It is also in strong interaction with WP2 to select the most advantageous materials for the targeted sensors, either based on photonic or optomechanical effects.

The first requirement for reaching the high sensitivity needed for the envisioned measurements is to obtain high quality factors. The two kinds of resonators studied in the project, photonic and optomechanical, both need a high optical quality factor (photonic sensors: Qo > 105; optomechanical sensors: Qo > 108). Several optical geometries will be investigated from micro-ring to photonic crystal cavity resonators. Going along with a high optical quality factor, high mechanical quality factor is also compulsory for optomechanical resonators. For these structures, both optical and mechanical modes, with their respective high quality factors, should also have a strong coupling. This so-called optomechanical coupling, overlap between the optical and the mechanical field, will be also investigated with Finite Element Methods (F.E.M.).

In order to reach high transduction between photons and phonons, one project's target is to reach state of the art values of the resonance frequency, around or above a few megahertz. Another key feature for optomechanical resonators is the f-Q product, the product of mechanical resonance frequency and quality factor. To be able to perform quantum experiments at room temperature, as targeted in WP3, the f-Q product has to be larger than 1012 Hz. Several strategies will be pursued to reach these high f-Q products, either by using a diffraction-limited cavity with a mechanical resonance frequency in the GHz or by drastically decreasing mechanical losses (anchor losses and thermo-elastic damping).

The first task of this WP is thus to design photonic and optomechanical structures and to optimize optical, mechanical and optomechanical parameters. Several partners have computation facilities whether it is for optical (F.T.D.T. simulation) or optomechanical (F.E.M. methods) design optimization. In the second task, the designed structures will be fabricated in the clean room facilities of the project partners with complementary know-how on material processing. These similar capabilities in terms of design and fabrication will ensure that the targets of this cornerstone WP are achieved.

 

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