Article comprising means for modulating the optical transparency of a semiconductor body, and method of operating the article

摘要

An article that comprises novel means for modulating the transparency of a semiconductor body in accordance with a modulating signal is disclosed. The body comprises one or more quantum wells (QWs), and the modulation mechanism comprises changing the free carrier distribution function in the QWs. An important feature of the inventive article is the use of (relatively long wavelength) inter-subband radiation (ISBR) to change the transparency of the body for (relatively short wavelength) inter-band radiation (IBR). In preferred embodiments the modulating signal is an electric field applied across the QWs, such that ISBR absorption can be tuned by means of the Stark effect. One embodiment of the invention makes it possible to rapidly modulate IBR, and another embodiment can form narrow (typically less than 10 ps) IBR pulses.