[Jenne and Kevin]
I started testing the REFL55 photodiode. With a light bulb, I saw ~270 mV of DC voltage from the photodiode but still could not see any RF signal. I connected the RF out from the spectrum analyzer to the test input and verified that the circuit was working.
I then set up the AM laser and looked at the laser light with REFL11 and an 1811 photodiode. I was able to see an RF signal and verified that the resonant frequency is 55 MHz.
The current setup is not very reliable because the laser is not mounted rigidly. Next, I will work on making this mounting more reliable and will continue to work on finding an RF signal with a flashlight.