Widely Tunable III–V/Silicon Lasers for Spectroscopy in the Short-Wave Infrared

Integrating III-V gain material with silicon photonic integrated circuits enables the realization of advanced laser sources and full integrated systems for optical communication and sensing applications. The availability of III-V/silicon laser sources operating in the 2-2.5 μm short-wave infrared wavelength range is very valuable for spectroscopic sensing since many important industrial gases and blood glucose have absorption bands in this wavelength range. In this paper, first we present our latest results on heterogeneously integrated III-V-on-silicon distributed feedback (DFB) laser arrays. A III-V-on-silicon DFB laser array covering the 2.27-2.39 μm wavelength range with 6 nm wavelength spacing is reported. This DFB laser array is employed as the light source for tunable diode laser absorption spectroscopy of different gases. A four-channel DFB laser array integrated with a beam combiner is used to perform spectroscopic sensing over a 7 nm spectral range without mode hopping at room temperature. Finally, we present our recent advances in widely tunable Vernier lasers based on heterogeneous integration and butt-coupling of the gain section. Continuous tuning near the absorption lines by thermally adjusting the laser cavity length enables high-resolution tunable diode laser absorption spectroscopy measurements together with wide wavelength coverage.