106 results about "Radiative transition" patented technology

The invention relates to a rare earth-based nano-crystalline cellulose fiber film having ultraviolet ray filtering performance and a preparation method thereof. The method comprises the following steps: nano-crystalline cellulose and a rare earth complex Eu(TTA)3(H2O)2 are mixed according to mass ratio of (10-33):1 and a mixture is added in ethanol, a backflow reaction is carried out; after reaction is completed, cooling and pumping filtration are carried out to obtain the rare earth-based nano-crystalline cellulose fiber film having ultraviolet ray filtering performance. In the preparation method, a rare earth Eu<3+> complex and nano-crystalline cellulose fiber are used to prepare the rare earth-based nano-crystalline cellulose through a solvent exchange method, and the film can be obtained through pumping filtration. The rare earth complex and nano-crystalline cellulose fiber with low cost are composited to the rare earth-based nano-crystalline cellulose fiber film, the prepared film can efficiently transfer the ultraviolet light to red light through radiative transition, and high light transmittance of visible light can be guaranteed.

A broadband CLE capable of operation simultaneously at multiple wavelengths comprises: a core region including a multiplicity or cascade of stages, each stage including a radiative transition region. A first group of stages emits radiation at a first wavelength and at a first aggregate intensity per group, and a second group of stages emits radiation at a second wavelength and at a second aggregate intensity per group lower than the first intensity. The invention is characterized in that the second group has more stages than said first group, and the per-stage intensity of the first group is greater than that of the second group. This design reduces the difference between said first and second aggregate intensities. In one embodiment, groups that are located at or near to the ends of the cascade have more stages than groups that are centrally located within the cascade regardless of their wavelength. Our invention significantly reduces variations in modal gain across the desired broadband spectrum and produces sufficiently flat gain without requiring elaborate redesign of the stages. These features enable cw operation of a broadband intersubband laser.

The invention relates to the design, fabrication, and use of semiconductor devices that employ deep-level transitions (i.e., deep-level-to-conduction-band, deep-level-to-valence-band, or deep-level-to-deep-level) to achieve useful results. A principal aspect of the invention involves devices in which electrical transport occurs through a band of deep-level states and just the conduction band (or through a deep-level band and just the valence band), but where significant current does not flow through all three bands. This means that the deep-state is not acting as a nonradiative trap, but rather as an energy band through which transport takes place. Advantageously, the deep-level energy-band may facilitate a radiative transition, acting as either the upper or lower state of an optical transition.

A method is presented for fabricating a semiconductor device operable to generate a THz spectral range radiation in response to an external field. According to this method, a heterostructure is formed from selected layers. The layers include at least first and second semiconductor layers made of materials having a certain initial overlap between the valence band of the second layer material and the conduction band of the first layer material. The heterostructure layers are arranged with a selected layout providing a quantum mechanical coupling between an electron quantum well (EQW) in said first layer and a hole quantum well (HQW) in said second layer. The layout is selected so as to define a predetermined arrangement of a plurality of energy subbands and a predetermined dispersion of these subbands to define a desired effective overlap between the energy subbands of said conduction and valence bands. This enables the device operation for generation of the THz spectral range radiation originating from multiple radiative transitions of non-equilibrium carriers including at least one transition from transitions between the following: energy subbands of the EQW, energy subbands of the HQW, and ground energy electron subband of the EQW and ground energy hole subband of the HQW.