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Optical low-coherence interferometry (OLCI) takes advantage of the variation in refractive index in silicon-wire microring resonator (MRR) effective lengths to perform glucose biosensing using MRR interferograms. The MRR quality factor (Q), proportional to the effective length, could be improved using the silicon-wire propagation loss and coupling ratio from the MRR coupler. Our study showed that multimode interference (MMI) performed well in broad band response, but the splitting ratio drifted to 75/25 due to the stress issue. The glucose sensing sensitivity demonstrated 0.00279 meter per refractive-index-unit (RIU) with a Q factor of ∼30,000 under transverse electric polarization. The 1,310 nm DFB laser was built in the OLCI system as the optical ruler achieving 655 nm characterization accuracy. The lowest sensing limitation was therefore 2 × 10−4 RIU. Moreover, the MRR effective length from the glucose sensitivity could be utilized to experimentally demonstrate the silicon wire effective refractive index with a width of 0.45 μm and height of 0.26 μm.

We experimentally demonstrate a tunable fiber ring laser with narrow linewidth and fine tuning resolution based on Er3+-doped fiber(EDF) laser material. A tunable fiber Bragg grating(FBG) filter is used in the system as the frequency selecting element, and a stepping motor together with a single chip acts as the precise tuning mechanism. The fiber ring laser has a narrow linewidth of ~0.07nm, a tuning resolution of ~1.5pm/pulse, an output power of ~25 mW, and a slope efficiency of ~17.9%.