Table 3.

Calculation of uncertainties of the first method experimental setup at ${\lambda }_{WM}\approx 1530\mathrm{nm}$.

Magnitude	Component of Uncertainty	Value (pm)	Type	Uncertainty Contribution (pm)
${\lambda }_{WM}$	Wavelength meter (WM) calibration	9.4 × 10−2	B	4.7 × 10−2
	Linewidth of FBG	1.4 × 100	B	3.9 × 10−1
	Repeatability of reference	4.0 × 10−1	B (*)	2.3 × 10−1
${\lambda }_{FBGI}$	Optical resolution	8.0 × 10−1	B	2.3 × 10−1
	Display resolution	1.0 × 10−2	B	2.9 × 10−3
	On-off repeatability	2.0 × 10−1	B (*)	1.2 × 10−1
	Expanded uncertainty (U) (k = 2)			±1.1 × 100

(*) Obtained by experimentally estimating the lower and upper bounds.