Large Optical Nonlinearities in Hybrid Semiconductor Devices

In hybrid semiconductor devices artificial optical nonlinearities can occur as a result of combined optoelectronic and electro-optical effects. The principle of such a two-step process is discussed in detail where basic structures as shown in Fig. 1 are considered. In particular, the device is assumed to exhibit firstly the properties of an optoelectronic photodetector, where optical power is absorbed to generate a photocurrent. Secondly, it is assumed that the same device simultaneously behaves as a modulator, where electrical signals control the optical output by using some electro-optical mechanisms. Obviously, both properties are coupled by the photocurrent which finally leads to a self-interaction process. As a result, a self-electro-optic effect occurs giving rise to an effective optical nonlinearity according to the following scheme As can be seen, an artificial optical nonlinearity is obtained which can electrically, i. e. externally be controlled.