Design of Control Electronics for Microwave Photonics Based Carrier Generation

Optical modulators having extremely low electro-optic response time supports high frequency modulating signals. This feature makes it highly attractive in comparison with microwave modulators. We propose a technique to generate microwave photonic signals modulated at very high bit rates by optical heterodyning. Optical heterodyning provides down conversion of corresponding modulated optical signals. The wavelength of the light emitted from the laser diode is sensitive to the temperature. Thus, the transistor based switching circuit is designed to control the ThermoElectric Cooler (TEC) module. The required temperature for the laser diodes is achieved by effectively sinking or sourcing the current into/from the TEC module. This in turn is dependent on the ambient temperature. In transistor based switching circuit the switching between the transistors takes place due to the variations observed by the thermistor housed inside the TEC module. Hence the design for temperature compensation elements based on the ThermoElectric Cooler (TEC) is proposed along with the constant current drive.