100 GHz ultra-high Q-factor photonic crystal resonators

We demonstrate an ultra-high Q-factor photonic crystal resonator operating in the millimeter-wave band, which is suitable for use as an integrated sensing platform. Experimental results show that at 100 GHz a loaded Q-factor of 5 000 and 8 700 can be achieved with a strongly and weakly coupled cavity design, respectively. The uncertainty in the experimental results has been analyzed and a new technique of propagating uncertainty in S-parameter measurements for the determination of Q-factor is given. The result of this uncertainty analysis gives an unloaded Q-factor of 9 040 ± 300; being fundamentally limited to ∼10 000 by the intrinsic dielectric loss of the high resistivity silicon substrate. Utilizing standard bulk-micromachining of silicon, the resonators can be monolithically integrated into RFICs and MMICs for applications including liquid and gas sensing.