Figure 1
From: Negative-index gratings formed by femtosecond laser overexposure and thermal regeneration
Transmission spectra of the original type I-IR fibre Bragg grating (FBG) (upper panel), highly polarization dependant phase-shifted FBG (P-PSFBG) (middle panel) and negative-index FBG (lower panel).
(a) Transmission spectra (left axis) and polarization-dependent loss (PDL) (right axis). (b) Transmission spectra of two orthogonal polarization modes (TE, TM). All measurements conducted at room temperature, 20 °C.
