Ed - First and foremost, there must exist a resonant cavity formed inside the semiconductor or in combination of the semiconductor die and its packaging. Then the threshold current (for population inversion of the lasing medium) must be exceeded. Only the latter is related to external faults of any kind. Without the former, you will not get any semiconductor diode to lase.
It seems likely that the resonant cavity would be inadvertent or incidental. I suppose it's possible that some diodes that don't meet spec for use as a laser _might_ get recycled as a common LED, so the effort in their creation isn't a total loss, but such is pure speculation. Regards, Peter L. Tarver, PE Product Safety Manager Sanmina Homologation Services peter.tar...@sanmina.com > From: Price, Ed > Sent: Wednesday, June 20, 2001 7:32 AM > > The discussion about LEDs "lasing" during a fault > condition started me doing > some review about LEDs. > > But first, what is the fault condition here? Is > this a condition where a > power source or limiting resistor fails, allowing > the LED to draw more > current than desired (although not enough to > destroy the LED), thus creating > a very bright LED? > > Or does something happen to the operation of the > LED, causing it to emit > coherent radiation and/or change its emission beamwidth? > > Regards, > > Ed > ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: pstc_ad...@garretson.org Dave Heald davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.rcic.com/ click on "Virtual Conference Hall,"
