Integrated optical-readout of a high-Q mechanical out-of-plane mode

• Published in: Light, science & applications science & applications, 2022-09, Vol.11 (1), p.282-282, Article 282
• Main Authors: Guo, Jingkun, Gröblacher, Simon
• Format: Article
• Language: English
• Subjects: 142/126; 639/624/399; 639/766/1130/2799; Crystal structure; Experiments; High temperature; Lasers; Microwaves; Optical and Electronic Materials; Optical Devices; Optics; Photonics; Physics; Physics and Astronomy; RF and Optical Engineering; Silicon nitride
• ISSN: 2047-7538; 2095-5545; 2047-7538
• DOI: 10.1038/s41377-022-00966-7

The rapid development of high- Q M macroscopic mechanical resonators has enabled great advances in optomechanics. Further improvements could allow for quantum-limited or quantum-enhanced applications at ambient temperature. Some of the remaining challenges include the integration of high- Q M structures on a chip, while simultaneously achieving large coupling strengths through an optical read-out. Here, we present a versatile fabrication method, which allows us to build fully integrated optomechanical structures. We place a photonic crystal cavity directly above a mechanical resonator with high- Q M fundamental out-of-plane mode, separated by a small gap. The highly confined optical field has a large overlap with the mechanical mode, enabling strong optomechanical interaction strengths. Furthermore, we implement a novel photonic crystal design, which allows for a very large cavity photon number, a highly important feature for optomechanical experiments and sensor applications. Our versatile approach is not limited to our particular design but allows for integrating an out-of-plane optical read-out into almost any device layout. Additionally, it can be scaled to large arrays and paves the way to realizing quantum experiments and applications with mechanical resonators based on high- Q M out-of-plane modes alike. Multilayer structures integrating a photonic crystal cavity and a mechanical resonator with a high- Q M out-of-plane mode are fabricated, exhibiting high optomechanical coupling.