Figure 2
From: Negative-index gratings formed by femtosecond laser overexposure and thermal regeneration
Transmission evolution of fibre Bragg grating (FBG) in case of overexposure.
(a) Transmission spectrum evolutions of the two orthogonal polarization modes (TE and TM) from original type I-IR fibre Bragg grating (FBG) to highly polarization dependant phase-shifted FBG (P-PSFBG) in case of overexposure. (b) Measured transmission loss and Bragg wavelength of P-PSFBG as a function of exposure time.
