Synergistic spectral tuning in 250 nm AlGaN deep-ultraviolet monolithic photonic chips

Spectral mismatch between on-chip emitters and photodetectors remains a critical bottleneck for AlGaN-based deep-ultraviolet (DUV) monolithic photonic integration. Here, a 250 nm AlGaN DUV monolithic integrated photonic chip with improved emission–detection spectral matching is demonstrated. By tailoring the aluminum content in the quantum barriers, the detector absorption edge is redshifted due to the enhanced quantum-confined Stark effect (QCSE), while the emission peak is blueshifted owing to the carrier screening effect (CSE) and strengthened quantum confinement effect (QCE). This spectral engineering broadens the emission–detection overlap region from 19 to 35 nm and enables complete coverage of the defined electroluminescence (EL) spectral width by the detector responsivity window. In addition, a photocurrent model based on the interplay between photovoltaic current and external-field-induced current is established to describe the bias-dependent on-chip signal conversion. On-chip DUV optical communication is further verified by 50 Mbps pseudorandom binary sequence transmission. These results provide a practical route for overcoming spectral mismatch in AlGaN DUV monolithic photonics and open a route toward high-performance integrated systems for optical communication and integrated photonic sensing.