PMC

The fiber strain testing setup for two reflective FBG spectral linewidth characterization.

a The frequency noise power spectral density for two different comb lines. At low offset frequencies, all comb lines display higher frequency noise than the pump due to the TRN, while at high offset frequency range, some comb lines close to the quiet mode may have lower frequency noise than the pump. b Comparison between Lorentzian and effective linewidth. Because of the low-frequency noise, the effective linewidth is higher than the Lorentzian linewidth, and the linewidth distribution appears symmetrically located with respect to the pump.

Simulation of (a) the spectral profiles of the generated beams from a single-pass SPDC (green), singly resonant oscillator (SRO) (orange), and doubly resonant oscillator (DRO) (blue); (b) singly resonant cross-correlation function; (c) doubly resonant cross-correlation function.
Terms: δυ_PM: phase-matching linewidth; δυ_mode: modal linewidth; Δν_fsr: free spectral range; τ₀: temporal linewidth; T_rt: round-trip time.

A. Change in linewidth as a function of first-order B0 inhomogeneity for 40 ms, 80 ms and 160 ms inherent linewidths in a (2cm)³ voxel. B. Change in linewidth as a function of first-order B0 inhomogeneity for varying voxel sizes, (1 cm)³, (2 cm)³, and (3 cm)³. C. Change in linewidth against second-order B0 gradient for ZX, ZY, XY, Z² and (X² – Y²) at an inherent linewidth of 80 ms. D. Spectral amplitude as a function of second-order B0 terms ZX, ZY, XY, Z² and (X² – Y²), relative to the amplitude in a homogeneous VOI.