CW blue-green light emission from GaN and SiC by sum-frequency generation and second harmonic generation

Continuous wave (CW) back-scattered sum-frequency generation (SFG) and second harmonic generation (SHG) have been obtained from GaN and SiC. GaN samples were obtained from GaN films grown by molecular-beam epitaxy (MBE), metalorganic chemical-vapor deposition and hydride vapor-phase epitaxy. The SiC samples were obtained from 3C SiC/Si grown by chemical vapor deposition (CVD), 4H and 6H single crystal SiC substrates. The samples were optically excited with two CW lasers at the red (840 nm) and the infrared (1.0 µm). SHG at 420 nm and 500 nm and SFG at 455 nm were observed. SFG and SHG were verified by measuring their relative intensities against the pumping laser power. The SHG signals from GaN and SiC samples are compared with that from KH2PO4 (KDP).