| 摘要 |
A light emitting device for generating at least one beam of output radiation from an input current of electrons comprises at least two p-n junction devices for converting the input current of electrons into photons, wherein the p-n junction devices are electrically connected in series such that the input impedance of the light emitting device is substantially equal to the sum of the individual impedance of the p-n junction devices. Hence the quantum efficiency of the light emitting device is substantially equal to the sum of the individual quantum efficiencies of the p-n junction devices. In a preferred embodiment, the light emitting device comprises a plurality of p-n junction devices connected in series such that the input impedance of the light emitting device is equal to 50 Omega without the need for additional circuitry or impedance matching elements. The device may therefore have a 50 Omega impedance over a broad frequency band, limited by the modulation frequency limit of the individual p-n junctions. Typically, the p-n junctions may be AlGaAs, AlGaInP, AlGaInAs or AlGaInAsp laser diode devices. The invention also relates to an optically coupled bipolar transistor device. |
