摘要： Sub-Wavelength Grating (SWG) periodic media are comprised of alternative dielectric layers with a pitch Λ small enough in comparison to the wavelength to supress any diffraction or interference effect. As a good first approximation, SWG media can be considered as uniform and lossless ones, with an averaging effect over the dielectric permittivity [1]. The use of SWG media as core and/or cladding materials of optical waveguides was first proposed and demonstrated in 2010 [2] as a way to realize easy engineering of the refractive guided index of light with simple lithographic patterning. Since then, SWG waveguides have found various applications such as waveguide crossing, multimode interferometers, optical filters, mid-infrared waveguides, or even optical biosensing [3]. We propose to include SWG waveguides within a suspended Fabry-Perot (FP) cavity (see Fig. 1a). The core of the cavity is formed by alternative Silicon and Air SWG layers, while the input and output mirrors are two Direct Bragg Reflectors (DBR). The whole structure is fully suspended through the use of two support arms. We present the theoretical modelization, technological realization and optical characterisations of such a cavity. The design was conducted through both an analytical model that treats SWG media with equivalent refractive indexes, and two dimensional effective index Finite-Difference Time-Domain (FDTD) simulations. Actual devices were realized on 200 mm silicon on insulator (SOI) wafers in our clean room facilities with e-beam patterning of the waveguide level, and characterized via full-scale wafer optical spectrum measurement between 1520 nm and 1580 nm. At time of writing, we measured optical quality factors of 10 000 over 2 μm long cavities. We believe this kind of suspended structure can be used in the field of Cavity Optomechanics, where an optical cavity is coupled to a mechanical resonator [4]. Indeed, because it is fully suspended, we await mechanical resonance to occur, the cavity behaving similarly to a doubly clamped holey cantilever (see Fig. 1c). Apart from the traditional optical phase shift occurring with propagation length variations of the cavity, there should also be a phase shift arising from the SWG nature of the waveguide, whose equivalent refractive index depends on the pitch Λ (and thus length) of the cavity. Due to this additional effect, we expect a strong optomechanical coupling rate.