5 ms·
The bands of laser diodes are not necessarily sharp, so there can be a significant difference between the injection voltage and the photon energy. The paper men
by fsh 7y ago
The bands of laser diodes are not necessarily sharp, so there can be a significant difference between the injection voltage and the photon energy. The paper mentions that their particular doping method produces a step-less valence band profile.
Furthermore, they need a fairly large current (0.4 A) to get this thing to lase. The "knee" in the U-I curve is at around 9 V and 0.05 A, so there seems to be a fair bit of voltage drop due to internal resistance of the device. This is probably also why they have to pulse the laser with a 0.01 % duty cycle in order not to produce too much heat.
- MayeulC 7y agoBy sharp, do you mean a direct band-gap? I recall that you sometimes want to pump your atoms in a higher energy state than the one that corresponds to the output energy, but I forgot its usefulness. Could someone enlighten me on this? Or is it just for optically pumped mediums (thus pumped with higher energy photons than the emitted ones)?
- fsh 7y agoIt is impossible to achieve inversion (and therefore gain) by optically pumping a medium exactly at the emission wavelength. Therefore, optically pumped laser gain media are at least three (usually four) level systems.