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I'm looking at the time reversed laser and I was having trouble understanding why we call this device a laser. To me this device is more like the absorbers found in FDTD codes, something like a CPML.

I am having trouble finding the analogs to the following processes in traditional lasers.

  1. What is the mechanism for feedback. In a laser we have stimulated emission producing an exponential increase in output intensity, until the system saturates. In the reverse laser I only see an attenuation constant, whose constant value to me seems exactly like an absorber and not a laser.
  2. Does this device have modes, does the feedback select an absorption width that narrows? The claims of an absorb band corresponding to the visible range (200nm-800nm) is a rather broad range that is characteristic of mostly everything?
  3. What does population inversion and threshold mean for the reverse laser? If it is an absorber doesn't that mean that even a single photon knocks it out stability. In one paper the authors described a 2 state reverse laser system, we know that a 2 state laser is not possible....

Some images of time reversed lasers.

enter image description here This also looks nice, maybe

Where is the lasing?

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Related: physics.stackexchange.com/q/9628/2451 –  Qmechanic Nov 8 '12 at 0:44
it is a to long and descriptive type of question. –  Curious Nov 24 '12 at 4:33
@MANIKANTABORAH you make me sad. –  Mikhail Nov 24 '12 at 4:59
Did you show this link eng.yale.edu/stonegroup/cpa/cpa.html And follow the all links which is given in this site? –  Android Boy Nov 27 '12 at 9:48
Because the absorption is using the same transition as a lasing transition, with a cavity, provides a narrow absorption line width(s)? With a saturable absorber, you also have the absorption (instead of gain) falling off with light irradiance, which is like a laser. –  daaxix Jan 1 '13 at 21:09
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protected by Qmechanic May 4 '13 at 12:57

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