of said multiplied second pulse pattern as illustrated in fig4 during which the laser is on a duty cycle d of 25 would mean for example that the laser is on during 25 of the time in each cycle d 50 appears to be an optimal duty cycle d it means that the duration during which the laser is at the high laser current write level ihwl is the same as the duration during which the laser is at the low level said duty cycle may nevertheless be chosen to be different effectively smaller duty cycles provide more power savings but they may lead to increased jitter thus the achievable power reduction is dependent on the duty cycle on the threshold current on the low level and on the losses in the internal capacitance associated with the laser caused by the switching the average light power reaching the optical medium is assumed to be the same this is not a necessary assumption this assumption means that if pulses with a duty cycle of 50 are realized the delta current should be twice as high resulting in the same average light power being emitted pulsing the laser according to the invention achieves a saving in threshold current the amount of threshold power that is saved when pulsing with a low level ll of zero is 1 d times the threshold power thus if a conventional pulse pattern is used and a duty cycle d is applied to the second multipled pulse pattern the power p saving is expressed by as.