Fig. 1. (Color online) (a) DWDM source optical micrograph. (b) Illustration and relevant dimensions of the side-wall sampled grating with equivalent phase shift. (c) SEM picture of the side-wall sampled gratings. (d) Input part of the MMI coupler.

Fig. 2. (Color online) The simulated C-SBG power reflectivity of the four channels.

Fig. 3. (Color online) Measured from SOA side of the four channels (a) wavelengths vs I_DFB when I_SOA = 150 mA, and V_EAM = 0 V under 20°C, and (b) optical spectra when I_DFB = 300 mA, V_EAM = 0 V, and I_SOA = 150 mA under 20 °C.

Fig. 4. (Color online) (a) Measured lasing wavelength of the four channels and the curve of its linear fitting. (b) Residual of the lasing wavelength and SMSR of the four channels. (c) Measured ER from coupled SMF of the four channels. (d) Channel 1 small signal E/O response at different V_EAM with I_DFB = 300 mA, I_SOA = 150 mA.

Fig. 5. Schematic structures of (a) C-SBG, (b) 2PS-SBG, (c) 3PS-SBG, and (d) 4PS-SBG. P is the sampling period.

Fig. 6. (Color online) Simulated power reflection comparison between (a) uniform grating (UG) and C-SBG, (b) 2PS-SBG and C-SBG, (c) 3PS-SBG and C-SBG, (d) 4PS-SBG and C-SBG.

Fig. 7. (Color online) (a) Measured optical spectra of the 8-channel laser array at 100 mA (left to right, channels 1 to 8) and (b) 8-channel lasing wavelengths and the linear fitting.

Table 1. Comparison between PS-SGB and C-SBG in terms of reflection characteristics and effective κ value.