c0f2bbb1   
   XPost: sci.electronics.design   
   From: gherold@teachspin.com   
      
   So I was putting ~100MHz sidebands on a diode laser (modulating the   
   current.) to get a frequency 'measure' of the length of a (~20cm)   
   Fabry-Perot cavity (confocal).  Wavlength ~780nm, FSR ~380 MHz, a   
   source at 190 MHz would be perfect, but I don't have anything that   
   high.  So I cranked up the power with 95 MHz and got the second order   
   sidebands at the frequency I wanted.  (RF voltage of about 1 Vp-p into   
   50 ohms so modulating the current by maybe +/- 10mA, it's not clear   
   how much of the RF gets into the diode.)   
      
   What was weird (unexpected) was that when I cranked up the RF power   
   the laser frequency shifted... but I had to *increase* the laser   
   current to get it back to the wavlength where it started.  The   
   increase in the DC current was a few mA out of ~50mA.   
      
   Anyone know what's going on?  I expected that adding RF would heat up   
   the diode and thus lead to a lower DC current.   
      
   Thanks,   
   George H.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)