Analysis of an integrated tunable spectrometer for the short to mid-infrared range based on a ring resonator

Abstract

An integrated, tunable spectrometer based on a silicon-on-sapphire platform is designed at wavelengths of 2.29-2.35 μm. Its pivotal component is a 4.7 μm-radius ring resonator on a graphene monolayer. Its full width at half-maximum and free spectral range are ∼1.5 and ∼45 nm, respectively, as found through a numerical simulation and theoretical computation. Sixteen characteristic peaks are obtained by tuning the Fermi level of graphene. The gap between the ring and waveguides is increased by 0.5 μm to increase the resolution, and though this can drastically reduce the transmission rate, an upper sapphire layer maintains light to the drop port.

Single-waveguide-based microresonators for optical sensing

“…It needs a K 2 than the latter to achieve s better ER, and it requires larger K 1 values than the former to get a better Q factor. Therefore K 1 and K 2 are set to 0.5 and 0.43, respectively, where a Q factor of 1.23 × 10 5 and an ER value of 62.1 dB can be obtained. The selected K 1 and K 2 can only be realized by varying the coupling gaps of corresponding couplers.…”

“…The devices basically rely on the overlap interaction between the evanescent wave and bioanalytes absorbed on device surfaces or in the surrounding medium [4] . They are typically based on siliconon-isolator (SOI) material systems offering extremely low absorption and bending losses, which allows many flexible geometry designs such as rings [5] , disks [6] , or toroids [7] . Their attractive properties, such as high quality factor (Q factor) and small footprint, mean that the light would circle the resonators dozens of times before being lost, which makes high power enhancement easy to achieve and, accordingly, makes attractive high sensitivity possible.…”