Nomenclature Explosion

Laser diode structures with a saturable absorber for high-energy picosecond optical pulse generation by combined gain-and Q-switching

“…As in previous papers [4,5], the gain spectrum was modelled using an infinite response digital filter, corresponding in frequency domain to a Lorentzian. The peak position and width were taken as carrier density dependent; specifically, the spectral shift of the gain peak frequency peak with carrier density was taken as linear, in good agreement with microscopic calculations using a model similar to that of [28,15], from which the value of d peak /dN=1.6×10 -5 s -1 cm 3 was taken; the broadening of the gain spectrum with carrier density was taken as approximately twice this value, so as to keep the long-wavelength edge of the gain spectrum approximately in the same place, also as suggested by microscopic calculations.…”

“…In the following experiments, the laser diodes were driven with a custom pulse generator that consist of a MOS switch and an LCR transient circuit [27,28]. In this kind of a driver, the current pulse amplitude and width are determined by the supply voltage (in the range of ~100V) and the LC time constant of the circuit, respectively.…”

“…Secondly and most importantly, we found that, with the high power pulses we are simulating, the absorber is very quickly (typically within the first half of the leading edge of the pulse) saturated completely, which makes the precise form of the (N) dependence not too important given a correct value of the unsaturated absorption 0 and a roughly correct carrier density 0 / for full absorption saturation. Calculations using the model of [28,15] imply that with the bulk material used in the experiments, the operating wavelength is within the plateau of the absorption spectrum, therefore the width of the absorption peak was taken much larger than that of the gain peak.…”