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.