Optically controlled optoelectronics

Combining the functions of photodetection and modulation in one integrated device and/or circuit can allow low-energy, high-speed optoelectronic systems that can have many different possible functions depending on the structure and/or circuits. Devices employing quantum well modulators are particularly interesting because of their high speed, small size, and low energy requirements.

A first generation of such devices, the self-electrooptic-effect devices (SEEDs) exploited feedback within the structure to enable a variety of analog and digital functions. Other structures use direct control of a modulator diode by a photodiode for high-speed operations such as converting a signal from one wavelength to another. The process of diffusive conduction – a very high speed internal resistive-capacitive process that can be seen inside diodes (see here for a discussion of the physics of this process) – can allow another category of high-speed “diffusive conduction” devices.