Speaker
Description
Telecom-band nanowire lasers [1-3] based on III-V materials require continuous-wave (CW) operation at room temperature for future photonic on-chip processors. However, most of the nanowire lasers reported so far have been operated under pulse-pumping conditions, and the few that have shown CW lasing did so only at cryogenic temperatures. The critical issue to hinder room-temperature CW lasing is thought to be excessive heating. The cross sections of nanowires are typically hexagonal or circular due to the growth conditions; therefore, the thermal resistance could be elevated because the contact region between the substrate and nanowire is minimal. In addition, low reflectance at the nanowire edge further increases the lasing threshold. Lastly, the nanowire can be heated up by a pump laser before reaching the lasing threshold.
In this work, the heating effects limiting laser performance is systematically investigated for nanowires placed on Au-coated substrates before and after Al2O3 deposition and on Si and SiN waveguides. First, we ascertain the characteristic temperature by changing the substrate temperature and estimate the nanowire temperature by changing the pumping laser frequency. Then, we compare the lasing behavior of nanowires on Au, Au with Al2O3, a Si waveguide, and a SiN waveguide. Our findings indicate that nanowire heating is strongly related to the thermal resistance between the nanowires and substrates. Our results reveal the potential for future continuous-wave nanowire laser operation, towards future photonic on-chip processors with nanowires integrated on photonic platforms.
[1] M. Notomi, et.al., Opt. Mater. Express, 10, 2560 (2020)`
[2] G. Zhang, et.al., Sci. Adv., 5, eaat8896 (2019)
[3] M. Takiguchi, et.al., APL Photonics, 2, 046106 (2017)
| Speaker Country | Japan |
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