Nonlinear Dynamics in Semiconductor Lasers 2023 - Abstract
Ackemann, Thorsten
Coauthors: S. Eisendorfer, J. Fletcher
The intriguing concept of photon condensation was originally proposed and demonstrated in microcavities filled with dyes [1] but more recent work yielded evidence for the same phenomenon in semiconductor microcavities [2]. We are investigating electrically pumped broad-area vertical-cavity surface-emitting lasers (VCSELs) very similar to the one investigated in [2] and vary injection current and ambient temperature. Ref. [2] reported a lower than expected fitted temperature for a moderate injection current (256 K for a substrate hold at 293 K) but did not provide a systematic investigation of the photon temperatures. We find consistently an exponential decay of the strength of the photoluminescence vs modal energy confirming thermalization of modes. For low injection currents the fits to the Boltzmann tail yields temperatures close to or slightly above room temperature as expected. However, for increasing injection currents the fitted temperatures drop significantly with increasing current and reach values below 200 K at the highest currents accessible. The scaling region becomes smaller and is confined to high energy modes. This indicates some non-equilibrium dynamics which is currently not understood.
[1] J. Klaers et al., Nature 468, 545 (2010)
[2] S. Barland et al., Opt. Exp. 29, 8368 (2021)