Abstract

Extensive research has been performed, with varying success, to develop red laser diodes which exhibit strong self-pulsation over an extended temperature range (0 - 80 °C) for optical storage applications. As an approach to understanding this problem we have investigated the dependence of self-pulsation characteristics in commercial CD laser diodes emitting at λ = 780 nm, when operated between T = 77 K and T = 310 K. Self-pulsation in these devices was found to extinguish below about T = 100 K. Measurements of the variation of self-pulsation frequency (v_sp) with bias current in the temperature range 150K to 310 K. (Fig. 1) showed a more sensitive dependence on bias current as the heatsink temperature decreases. When this data was viewed (Fig. 2) in the more conventional form, v_sp versus normalised bias current (I/I_th - 1), it is clear that the slope of these curves are not strongly temperature dependent. These results are interesting since it is commonly assumed that the selfpulsation frequency in CD laser structures occurs at the laser diode modulation resonance frequency (Ω_R) which predicts a quadratic dependence of normalised bias current on Ω_R and a temperature dependence of the slope due to the well known temperature dependence of carrier life - neither of which are apparent.

© 1998 IEEE