From your description in post #5, the input signal is *controlling* the LEDs, not powering them. This is an important distinction. Knowing which parts of your system are power supplies and which parts are not is critical to explaining what you want and understanding how things work.
Also, the LEDs need 100 mA, not mV. Amperes and Volts are different. And, at 100 mA per LED you will need a 0.5 A poser source and a medium-sized power transistor to drive the LEDs. The vast majority of opamps cannot make a 0.5 A output current.
Is it a requirement that the LEDs flicker at the same frequency as the input signal, or can they be on steady-state? If the latter, since the input is an on-off signal, all you really need is a comparator as a missing-pulse detector driving a power transistor. The resulting circuit can run on just the +9 V supply if you want.
ak