Ultraviolet picosecond optical pulse generation from external cavity modelocked GaN based laser/diodes

摘要

Modelocked semiconductor lasers have been studied quite extensively by many research groups motivated by their compactness and capability of generating subpicosecond optical pulses. Those works are, however, mostly done in near infrared wavelength range owing to the lack of available semiconductor optical amplifiers (SOA) in visible or ultraviolet region. Recent developments of GaN based semiconductor lasers have made it possible that semiconductor lasers can cover entire wavelength range from UV to IR. Ultrashort optical pulses of wavelength near 400 nm are typically generated by the frequency doubling of modelocked Ti : Sapphire lasers or dye lasers output. In view of this fact, modelocked semiconductor lasers at these wavelengths are very attractive light sources due to their compact and efficient nature. In addition, subsequent frequency doubling of these semiconductor lasers output can generate light at ～200 nm for lithography applications. In this paper, we present ultraviolet picosecond optical pulse generation from external cavity actively modelocked InGaN lasers.