Fig. 1. (a) Schematic diagram of the experimental setup for writing FBG and FBG arrays; (b) physical images of RIM regions of varying sizes.

Fig. 2. RIP of the drawn 1 km-long fiber.

Fig. 3. Resonant spectral transmission and reflection of the 3# FBG sample at 1555 nm.

Fig. 4. Spectral characteristics of the fabricated FBG. (a) 1# sample, without slit shaping and the super-Gaussian apodization region; (b) 2# sample, with the super-Gaussian apodization region; (c) 3# sample, with a 500 µm narrow slit and super-Gaussian apodization.

Fig. 5. Reflection response spectra of the fabricated FBG array.

Fig. 6. (a) Relationship between the Bragg wavelength and the electric oven temperature; (b)–(e) reflection response spectra of the fabricated FBG at different temperatures (25°C, 135°C, 225°C, and 350°C).