The Improved Quasi-Fermi-Level Separation of InGaAs Well-Cluster Composite Nanostructure for Ultra-Wide Tunable Lasers

The development and application of tunable lasers have been constrained by a limited tuning range, primarily due to the small quasi-Fermi-level separation (ΔEf) and low carrier band filling levels. This study demonstrates an InGaAs/GaAs well cluster composite (WCC) nanostructure, developed based on the indium-rich cluster effect. The ΔEfand gain curves were obtained and analyzed by collecting photoluminescence (PL) spectra emitted from two 500-μm-long multisection regions under varying carrier concentrations (9.0 × 1017–9.6 × 1017cm−3) and working temperatures (280–330 K). Compared to traditional InGaAs/GaAs quantum well structures under identical working conditions, the ΔEfand gain bandwidth of the WCC structure were observed to be 1.08 and 5.3 times higher. This enhancement is attributed to the formation mechanism of the WCC structure, which contributes to a broader ΔEfand expanded spectral characteristics. This configuration highlights the significant application potential of the WCC nanostructure in advancing tunable laser technology.