Abstract

Diode-pumped, intracavity-doubled Nd:YAG, Nd:YVO₄ green lasers, KTiOPO₄ (KTP) sum frequency mixing, KNbO₃ resonant ring doubler, periodically-poled KTP and LiNbO₃ waveguide blue lasers, and IIVI blue laser diodes are promising sources for future 4 to 5 time pit density optical disks. Although the blue diode (460nm) is expected to reduce the intersymbol interference in read out signal from higher density optical disks, considering its probable beam aspect ratio, astigmatism, and the spectral sensitivity of a Si PIN photodetector, at least 5mW room temperature cw output will be required for its future application. Efficient blue harmonic generation of Ti:Sapphire lasers in a periodically-poled LiNbO₃ waveguide and in a Cerenkov-radiation mode Ta₂O₅/KTP waveguide were also demonstrated. Their efficient stable coupling with a diode will be next key issue. Only applications of bulk nonlinear frequency conversion to actual optical disk systems have been demonstrated so far.

© 1993 Optical Society of America