Abstract

Low astigmatism in high power semiconductor lasers is desirable for optical storage use. In general, the relationship between astigmatism and the waveguiding mechanism is known. In fact, the amount of index and gain guiding in a given laser structure plays an important role in determining the astigmatism at a given power. We measured the astigmatic length and its optical power dependency for AlGaAs singlequantum well graded-index separate-confinement ridge waveguide lasers and for conventional laser structures such as channeled substrate planar (CSP). At low output power (2 mW), we observed 0.8-µm astigmatic length for the single-quantum well laser compared with 4.1 µm for the CSP laser. As the single-quantum well laser output power is increased, the astigmatic length is almost power-independent, shifting <0.5 µm at 40 mW. In contrast, the astigmatic length of the CSP laser shifts dramatically to –0.25 µm at 40 mW. In addition, calculations of astigmatic length using previously published models do not take into account optical power dependency and yield values much larger than the measured ones.

© 1989 Optical Society of America