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

Method of operating an article that comprises a semiconductor body comprising a multilayer structure comprising at least one quantum well (QW);

• associated with said QW being a bandgap energy and a subband energy difference;
• associated with free carriers of a first conductivity type in the QW being a free carrier distribution function, and associated with the body is a lattice temperature;
• the method comprising
• a) providing electromagnetic radiation of a first wavelength to the body;
• and
• b) providing a modulation signal to the body;
• characterized in that
• c) the first wavelength is selected to correspond to said bandgap energy, the first wavelength radiation to be referred to as "inter-band radiation" or "IBR";
• and the method further comprises
• d) providing electromagnetic radiation (to be referred to as "inter-subband radiation" or "ISBR") of a second wavelength to the body, the second wavelength being longer than the first wavelength and selected such that the free carrier distribution function is varied in accordance with the modulation signal, such that the IBR is modulated in accordance with the modulation signal, the modulated IBR being emitted from the body;
• and
• e) providing modulated IBR utilization means.

An article comprising

• a) a semiconductor body;
• b) contact means adapted for providing an electric field across the body, the contact means comprising at least one substantially planar contact quantum well (QW) layer, with a charge carrier gas in said contact QW layer;
• c) means for providing electromagnetic radiation to the body, associated with said radiation being a photon energy, a polarization and an electric vector, said means for providing the radiation being adapted for providing to the body radiation that is, in the body, substantially TM polarized, with electric vector substantially normal to the plane of the contact QW;
• and
• d) associated with the charge carrier gas in the contact QW layer is a minimum energy that can be absorbed from said polarized radiation;
• and
• e) the composition and thickness of the contact QW layer are selected such that said photon energy is less than said minimum energy.

An article comprising

• a) at least a first quantum well (QW) in a semiconductor body;
• b) means for providing a modulating signal to the body, said means comprising contact means adapted for applying an electric field across the body;
• c) means for providing inter-subband radiation (ISBR) to the body, associated with said ISBR is a photon energy selected such that ISBR is substantially not absorbed in the first QW for a first given value of applied electric field, and such that ISBR is absorbed in the first QW for a second given value of applied electric field, whereby modulated ISBR can be emitted from the body;
• and
• d) modulated ISBR utilization means;
• wherein
• e) said contact means comprise at least a second quantum well, to be designated "contact QW", with a carrier gas in said contact QW, associated with the carrier gas in the contact QW is a minimum energy which can be absorbed from said ISBR, the composition and thickness of the contact QW selected such that the photon energy associated with ISBR is less than said minimum energy.