Figure 4

Typical experimental spectra and tunability of Vernier spectrum. (a) and (b) are reflection spectrum of the θ-shaped microfiber resonator with FSR 1 = 0.194 nm and the corresponded Vernier spectrum with FSR r = 6.253 nm, respectively. (c) and (d) are reflection spectrum of the θ-shaped microfiber resonator FSR 1 = 0.196 nm and the corresponded Vernier spectrum with FSR r = 8.917 nm, respectively.