Photonic devices optical switches

Nonlinear optical organic materials such as porphyrins, dyes, and phthalocyanines provide optical limiting properties for photonic devices to control light frequency and intensity in a predictable manner. The optical limit of CNTs composites is saturated at CNTs exceeding 3.8wt% relative to the polymer mass (Chen et al., 2002). Polymer/ CNT composites could also be used to protect human eyes, for example, optical elements, optical sensors, and optical switching (Cao et al., 2002). 

Losses still occur in the fibres developed for commercial use. Nonetheless, these have been reduced to a point where transmission over kilometres is possible. Along with transmission of information in telephone systems and similar applications, it has been suggested that optical devices may replace conventional electronics in more advanced applications such as computers. For such applications, it will be necessary to develop optical switches, amplifiers, and so on. In the last two decades, new materials have been developed that may form the basis of integrated optical circuits. These materials are photonic crystals. 

Another important characteristic of semiconductors is their optical absorption properties. The optical properties of semiconductors are crucial to their uses as photovoltaic energy conversion devices, photonic detectors, light-emitting diodes, solid state lasers, and optical switches see Semiconductor Interfaces). Some semiconductors absorb both visible and ultraviolet light, while others only absorb photons in the... 

In a semiconductor, some of the most important electronic transitions arise from the optical excitation of an electron across the semiconductor band gap. This excitation leads to the promotion of an electron from an orbital in the valence band to an orbital in the conduction band. This fundamental and extremely important process is crucial to the use of semiconductors as photovoltaic devices, photonic detectors, and optical switches. It is possible to understand the optical properties of semiconductors using the band structure formalism described above. 

Polynuclear complexes, molecular dyads, triads, and other supermolecules composed of redox- and photo-active metal polypyridine units have a great promise as components of future molecular electronic or photonic devices as optical switches, relays, memories, etc. [38, 46],... 

Substantial progress has been accomplished in the fabrication of molecular and biomolecular optoelectronic devices. Light-activated molecular and bio-molecular systems have been integrated with electronic transducers, and the optical switching of the systems has been electronically transduced to the macroscopic environment. In particular, the photonic switching of an electron-transfer cascade has allowed the amplified electronic transduction of an input... 

A current challenge is the development of efficient strategies for the design of switchable nonlinear optical (NLO) materials. The ability to switch the NLO activity of a molecule on and off is of relevance for the development of molecular photonic devices, as those properties can be... 

Near resonant z-scan studies provide both nonlinear refractive coefficients, ni, and two photon absorption coefficients, p. Results for a selection of PDAs in solution at 532 nm are given in Table 1. Diethylamino-PDA (lid) and the related quatemized polymer (15a) show comparable magnitudes of nonlinear absorption and refraction to those of poly-4-BCMU, with figures of merit, T, which satisfy the requirement for nonlinear optical switching devices. The metal-containing PDAs... 

---