Microwave Photonics

Basic components: RF -> optical : CW source and a modulator. opical -> RF : Photodetector. OIP3 (output intercept point). Assumption in all math: output noise independent of input power. phase change with thermal conductivity: optical fibre is chosen over RF cable. Direct Modulation: Shot noise : -168 dBm , Thermal noise : -174 dBm. Laser relative intensity noise(RIN): We do not desire RIN peaks in the passband. shot noise = 2*q*I*R*B. B- Bandwidth, linear with current. thermal noise = k*T*B. We would like to approach the shot noise limited performance. RIN is proportional to (I^2). Noise factor = (effective input noise)/(Thermal noise). Effective input noise is (output noise)/(Gain). <math>1/3</math>