Fig. 1. (a) Schematic of the widely tunable III-V-on-silicon laser; (b) microscope image of the fabricated laser.

Fig. 2. (a) Simulated reflectivity of DBR1 and DBR2. The inset shows the cross section of the fabricated DBRs; (b) dependence of the reflection spectra on the pitch of DBR1; (c) simulated transmission spectra of the two MRRs and Vernier filter; (d) longitudinal modes of the Fabry–Perot cavity filtered by the Vernier filter.

Fig. 3. (a) Gain spectrum of the III-V-on-silicon SOA at 150 mA at 5°C. The inset shows the fiber-to-fiber transmission spectra of the silicon waveguide with (in red) and without (in black) integrated SOA. (b)–(d) Emission spectra from III-V-on-silicon Fabry–Perot lasers with different DBR pitches. All Fabry–Perot lasers are driven at 160 mA at 5°C in CW regime.

Fig. 4. (a) CW L-I curve of the III-V-on-silicon Vernier laser with 420 nm DBR and MRRs with quality factor of 1500; (b) a fiber-coupled emission spectrum of the Vernier laser.

Fig. 5. Fiber-coupled emission spectrum of the laser with different MRRs. (a) Q≈500, biased at 160 mA at 5°C; (b) Q≈5000, biased at 160 mA at 0°C.

Fig. 6. Superimposed CW lasing spectra of lasers with (a) DBR pitch of 420 nm and MRR Q factor of 2500, (b) DBR pitch of 435 nm and MRR Q factor of 2500, and (c) DBR pitch of 460 nm and MRR Q factor of 1500. All lasers are biased at 160 mA, the two lasers with the higher Q MRRs are measured at 0°C, and the laser with lower Q is measured at 5°C. (d) Dependence of the lasing wavelength on the electrical power dissipated in the two MRRs of the laser shown in (b).

Fig. 7. Superimposed lasing spectra (pulsed) of lasers with (a) DBR pitch of 420 nm and MRR Q factor of 2500 and (b) DBR pitch of 460 nm and MRR Q factor of 1500. Both lasers are driven at 150 mA at 5°C.

Fig. 8. Superimposed CW lasing spectra obtained by tuning both MRRs.

Fig. 9. Spectral map of fiber-coupled emission spectrum of a Vernier laser as a function of bias current at 5°C in CW regime.

Fig. 10. (a) Contour map of the fiber-coupled laser spectra after the light has passed through the CO gas cell; (b)–(d) TDLAS spectrum of CO gas and the corresponding HITRAN spectrum at different absorption lines. The driven current used in the TDLAS measurements is shown in the respective figures.