Abstract: Visible and infrared light sources on silicon that have several attractive properties with respect to integrated optics. First, the devices are operational at room temperature and strictly require no thermal processing in their synthesis (although low temperature annealing can be used to form Ohmic contacts). These devices could therefore be included at any stage of chip fabrication. The special ease of synthesis of these silicon LEDs enables simple fabrication of surface structures such as patterned emitters and photonic crystal surfaces that enhance light emission in the forward direction. The LEDs are color-switchable—by reversing the current one can switch from infrared emission to visible emission. The lifetime of the luminescence is much shorter than the standard carrier recombination time in silicon, suggesting direct modulation of the emitted light.

Abstract: Visible and infrared light sources on silicon that have several attractive properties with respect to integrated optics. First, the devices are operational at room temperature and strictly require no thermal processing in their synthesis (although low temperature annealing can be used to form Ohmic contacts). These devices could therefore be included at any stage of chip fabrication. The special ease of synthesis of these silicon LEDs enables simple fabrication of surface structures such as patterned emitters and photonic crystal surfaces that enhance light emission in the forward direction. The LEDs are color-switchable—by reversing the current one can switch from infrared emission to visible emission. The lifetime of the luminescence is much shorter than the standard carrier recombination time in silicon, suggesting direct modulation of the emitted light.

Abstract: Tunable photonic crystals offer an interesting possibility to adjust the photonic band gap (PBG) as per requirement. Various methods of achieving this have been tried that include polarization of liquid crystals, thermal effects and more. Chromogenic devices provided in accordance with the present invention include combinations and subcombinations of electrochromic, photochromic, thermochromic devices featuring TMO based inverse opals having tunable photonic band gaps (PBG) for certain frequencies. Electrochromic (EC) materials in which a reversible optical property change can be induced with the application of a small electric field offer a novel possibility to tune the PBG in a controlled and reversible way. The reversible chemical change and the ensuing change of optical constants in these periodically arranged EC materials make the PBG tunability possible. In a recent work we have demonstrated for the first time the PBG tunability of EC materials deposited in the form of periodic inverse opals.

Abstract: Tunable photonic crystals offer an interesting possibility to adjust the photonic band gap (PBG) as per requirement. Various methods of achieving this have been tried that include polarization of liquid crystals, thermal effects and more. Chromogenic devices provided in accordance with the present invention include combinations and subcombinations of electrochromic, photochromic, thermochromic devices featuring TMO based inverse opals having tunable photonic band gaps (PBG) for certain frequencies. Electrochromic (EC) materials in which a reversible optical property change can be induced with the application of a small electric field offer a novel possibility to tune the PBG in a controlled and reversible way. The reversible chemical change and the ensuing change of optical constants in these periodically arranged EC materials make the PBG tunability possible. In a recent work we have demonstrated for the first time the PBG tunability of EC materials deposited in the form of periodic inverse opals.