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You might think "What is PG-FROG? Is it kind of ... errr ... brand new reptile or something?! Or, FROG with Parent's Guide?!". Almost all people in this world might think in this way. Of course it is incorrect. This is a story of Optics. FROG stands for "Frequency Resolved Optical Gating", and PG stands for "Polarization Gate", which were termed by Rick Trebino's research team. ...are you feeling like escaping from this webpage? Wait! This webpage is intended for introducing the concept of FROG to those who think "What the hell is FROG anyway?". The idea of FROG was invented by Rick Trebino's research group in 1993. In order to conduct the measurement of ultrashort optical pulse, some intricated technique is necessary. Actually it was impossible in the past, but with the emergence of FROG, it is going to be possible. The idea of FROG is very sophisticated, which is organized by two procedures. First, we measure the spectrum of the target pulse. We get such measurement result like below: 
The second step is, reconstruct the target pulse from the obtained data. The reconstruction procedure requires iterative calculation algorithm which is shown below. 
Here it should be noted that this algorithm is only for PG(Polarization-Gate)-FROG. For another FROGs, such as SHG FROG, SD FROG, another procedure has to be plussed. I made a Simulator for this reconstruction procedure. This Simulator's procedure is organized as follows: 1. Create the original pulse 2. Create the data of |Esig| (spectrum) from the original pulse 3. Only from the created |Esig| data, reconstruct the original pulse We can get to know if the reconstruction algorithm is valid or not (if there is no bug in the Simulator's program :-). If your CPU is slower than this, your PC might stop. ok ... that is all my brief introduction to this Simulator. Please enjoy this Simulator ! |