Ultrahigh-quality-factor silicon-on-insulator microring resonator

Abstract

The development of ultrahigh-quality-factor (Q) silicon-on-insulator (SOI) microring resonators based on silicon wire waveguides is presented. An analytical description is derived, illustrating that in addition to low propagation losses the critical coupling condition is essential for optimizing device characteristics. Propagation losses as low as 1.9 +/- 0.1 dB/cm in a curved waveguide with a bending radius of 20 microm and a Q factor as high as 139.000 +/- 6.000 are demonstrated. These are believed to be the highest values reported for a curved SOI waveguide device and for any directly structured semiconductor microring fabricated without additional melting-induced surface smoothing.

Silicon-based on-chip multiplexing technologies and devices for Peta-bit optical interconnects

“…Another potential way to achieve a large FSR is to depress the resonance peaks except the one to be used so that there is only one major resonance peak with a high ER over a broad band, which indicates an ultra-large quasi-FSR. It is well known that a high ER is achieved for the resonance wavelengths when the following critical coupling condition is satisfied [62] …”

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“…The high refractive index contrast between silicon and silicon dioxide enables one to design waveguides and devices with sub-micron features, greatly miniaturizing photonic integrated circuits [2], [26]. Devices using the SOI/CMOS technology have been fabricated recently with attractive optical functions and good performance including: high quality-factor resonators [27], [28], 80% efficiency vertical grating couplers [29], waveguides with small propagation losses (less than 2.5 dB/cm [4]), and low-loss, small-bend-radius waveguides (radii as small as 2 µm with 0.029 dB loss per 90…”

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