Figure 4
From: Negative-index gratings formed by femtosecond laser overexposure and thermal regeneration
Spectra of the final negative-index FBG.
(a) Measured reflection spectrum (left axis) and measured transmission spectrum (right axis). (b) Measured and simulated reflection spectra of two orthogonal polarization modes TE (b1) and TM (b2). BW, bandwidth. Inserts: index profile models used in simulation (b3: index profile model in TE polarization, b4: index profile model in TM polarization, the grating pitches are exaggerated 200 times for clarity).
