Recent demonstrations of optically pumped lasers based on GeSn alloys put forward the prospect of efficient laser sources monolithically integrated on a Si photonic platform. For instance, GeSn layers with 12.5% of Sn were reported to lase at 2.5 µm wavelength up to 130 K. In this work, we report a longer emitted wavelength and a significant improvement in lasing temperature. The improvements resulted from the use of higher Sn content GeSn layers of optimized crystalline quality, grown on graded Sn content buffers using Reduced Pressure CVD. The fabricated GeSn micro-disks with 13% and 16% of Sn showed lasing operation at 2.6 µm and 3.1 µm wavelengths, respectively. For the longest wavelength (i.e 3.1 µm), lasing was demonstrated up to 180 K, with a threshold of 377 kW/cm² at 25 K.
Silicon
photonics continues to progress tremendously, both in near-infrared
datacom/telecoms and in mid-IR optical sensing, despite the fact a
monolithically integrated group IV semiconductor laser is still missing.
GeSn alloys are one of the most promising candidate materials to realize
such devices, as robust lasing under optical pumping was demonstrated
by several groups up to mild cryogenic temperatures. Ideally, the
integrated lasers should be tunable by design over a wide spectral
range, offering a versatility that is required for optical sensing
devices. We present here an innovative approach, taking advantage
of local strain management in the semiconductor laser’s active
zone. Arrays of differently strained Fabry-Pérot GeSn microlasers
were fabricated side-by-side on the very same chip after blanket epitaxy
on a Ge-buffered silicon-on-insulator substrate. Thanks to the local
strain design, laser emission over a very large wavelength range under
optical pumping, with laser lines peaking from 3.1 up to 4.6 μm
at 25 K and with thresholds lower than 10 kW·cm–2. Laser operation persists up to 273 K, that is, very close to room
temperature. This strategy, implemented on group IV semiconductors,
opens up a new route to control the emission properties of microlasers
integrated on a chip over significant photon energy windows representing
a significant step forward in the integration and miniaturization
of light sources emitting at a process-defined wavelength.
Cavity mode analysis of photoluminescence spectra of uniaxial tensile stressed GeOI micro-bridges is shown. Several cavity modes show a strong increase of the Q-factor, which is signature of the emergent optical amplification due to gain.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.