GeSn Lasers Covering a Wide Wavelength Range Thanks to Uniaxial Tensile Strain

• Published in: ACS photonics Vol. 6; no. 10; pp. 2462 - 2469
• Main Authors: Chrétien, Jérémie, Pauc, Nicolas, Armand Pilon, Francesco, Bertrand, Mathieu, Thai, Quang-Minh, Casiez, Lara, Bernier, Nicolas, Dansas, Hugo, Gergaud, Patrice, Delamadeleine, Eric, Khazaka, Rami, Sigg, Hans, Faist, Jerome, Chelnokov, Alexei, Reboud, Vincent, Hartmann, Jean-Michel, Calvo, Vincent
• Format: Journal Article
• Language: English
• Published: American Chemical Society 16.10.2019
• Subjects: strain; nanophotonics; germanium tin laser; group IV; tunability
• ISSN: 2330-4022; 2330-4022
• DOI: 10.1021/acsphotonics.9b00712

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.