Ultra-high Q planar silicon microdisk resonators for chip-scale silicon photonics

Abstract

We report the fabrication and experimental characterization of an ultra-high Q microdisk resonator in a silicon-on-insulator (SOI) platform. We examine the role of the substrate in the performance of such microdisk resonators. While substrate leakage loss has warranted the necessity of substrate undercut structures in the past, we show here that the substrate has a very useful role to play for both passive chip-scale device integration as well as active electronic device integration. Two device architectures for the disk-on-substrate are studied in order to assess the possibility of such an integration of high Q resonators and active components. Using an optimized process for fabrication of such a resonator device, we experimentally demonstrate a Q approximately 3 x 10(6), corresponding to a propagation loss approximately 0.16 dB/cm. This, to our knowledge, is the maximum Q observed for silicon microdisk cavities of this size for disk-on-substrate structures. Critical coupling for a resonance mode with an unloaded Q approximately 0.7 x 10(6) is observed. We also report a detailed comparison of the obtained experimental resonance spectrum with the theoretical and simulation analysis. The issue of waveguide-cavity coupling is investigated in detail and the conditions necessary for the existence or lack of critical coupling is elaborated.

Dielectric microcavities: Model systems for wave chaos and non-Hermitian physics

“…For semiconductor microdisks the highest Q-factors can be achieved for "large" silicon cavities. Here, the Q ranges from 3 · 10 6 to 6 · 10 7 with disk radius of 20 − 60 µm Kippenberg et al, 2006;Soltani et al, 2007).…”

Multichannel cavity optomechanics for all-optical amplification of radio frequency signals

“…4d. Similar silicon micro-disk cavity with quality factor as high as 3 million has been reported in the literature 38 so it is possible to achieve even higher GF with a much lower power level. Although the operation speed of the device currently is limited by the relatively low mechanical frequency of the cantilevered signal waveguide, it is feasible to improve the mechanical frequency to the hundreds of megahertz range 39,40 , making it suited for radio-frequency (RF) photonics applications.…”

Silicon Multimode Photonic Integrated Devices for on-Chip Mode-Division-Multiplexed Optical Interconnects

“…This design rule usually works well especially for low index-contrast (∆) optical waveguides (e.g., SiO 2 -on-Si buried optical waveguides). However, it becomes very different for small optical waveguides with very high ∆, e.g., submicron SOI waveguides, which have been used widely for ultra-compact CMOS-compatible PICs [45][46][47][48][49][50][51][52][53][54][55][56]. For high-∆ optical waveguides, mode conversion between the eigenmodes may occur in an adiabatic tapered structure due to the mode hybridization at some special waveguide widths [57][58][59][60][61][62].…”