Fig. 1. Schematic diagrams of (a) the proposed DW laser, (b) the cross section of the DW laser chip, and (c) the distribution for the sampling grating period in the CSG. SCH-MQW, separate confinement hetero-structure-multi-quantum well; TAR, tail absorption region; SOA, semiconductor optical amplifier.

Fig. 2. (a) Sampling period of the CSG with two π-EPSs with various chirp rates for different wavelength spacing. (b) Simulated transmission spectra of chirped grating in front + mid, mid + rear, and total (front + mid + rear) with Bragg spacing at 0.8 nm.

Fig. 3. Simulated transmittance spectra of sampled grating with (a) high and (b) low Δn₀ at different Bragg spacing. (c) Simulated relationship between the Bragg spacing and the mode spacing of the sampled grating with Δn₀ at 0.0016 and 0.0005.

Fig. 4. Mode wavelength spacing of the DW laser with Bragg spacing at 0.4 nm and varying n_eff in front and rear sections.

Fig. 5. (a) Microscopic top view of the proposed DW laser and (b) the PI curve for the DW laser in the range of 0 to 240 mA.

Fig. 6. Mapping diagrams about the spectra of the DW laser at the C band with high Δn₀ and the wavelength shift of two modes by varying (a) I_SOA from 0 to 60 mA, (b) I_rear from 30 to 90 mA, and (c) I_front from 30 to 80 mA.

Fig. 7. Spectra of the DW laser with high Δn₀ with various (a) I_rear and (b) I_front at different states.

Fig. 8. Mapping diagrams about the spectra of the DW laser in the O band with low Δn₀ and the wavelength shift of two modes by varying (a) I_SOA from 0 to 60 mA, (b) I_rear from 90 to 180 mA, and (c) I_front from 90 to 120 mA.