35.5 MHz and 38MHz sideband frequencies are chosen for 1.45 " refcav. These frequencies will be suitable for cavities formed by 0.5/0.5m RoC mirrors and 1.0/1.0m RoC mirrors.
a) For0.5m/0.5m RoC mirrors 1.45" cavity, f1 = 35.5MHz. b) For0.5m/0.5m RoC mirrors 1.45" cavity, f2 = 38MHz
c) For 1m/1m RoC mirrors 1.45" cavity, f1 = 35.5MHz d) For 1m/1m RoC mirrors 1.45" cavity, f2 = 38MHz
Since we will use a crystal oscillator to drive the EOMs, I have to check how much power we need for the sideband.
If the crystal oscillator can provide us with enough power, we can use the crystal to drive a broadband EOM directly. Otherwise we will need an EOM driver, or a resonant EOM.
==shot noise level vs mod index(Beta)==
To see how much should the mod index be, I plot shot noise level vs Beta, with Power intpu = 1mW and 2 mW, and Finesse = 1e5 (for T=300 ppm mirrors)and 2e5 (For AlAs/GaAs coatings), with mode match = 80%. It seems that for the lowest shot noise level, we need beta = 0.8.
For resonant EOM, mod depth = 0.2 rad/V, for BB EOM, mode depth = 15mrad/V , see psl:745. These correspond to 4V (25dBm) and 53 V (47dBm) for the resonant and BB EOMs, respectively.