Optical modulators using semiconductor nano-structures: Difference between revisions

Revision as of 00:44, 8 June 2017

Revision as of 01:01, 21 November 2017

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[[Optical modulators]] can be implemented using Semiconductor Nano-structures to increase the performance like high operation, high stability, high speed response, and highly compact system. Highly compact [[electro-optical modulators]] have been demonstrated in compound semiconductors.<ref>Sadagopan, T., Choi, S. J., Dapkus, P. D. & Bond, A. E. Digest of the LEOS Summer Topical Meetings MC2–-3 (IEEE, Piscataway, New Jersey (2004)</ref> However, in [[silicon photonics]], electro-optical modulation has been demonstrated only in large structures, and is therefore inappropriate for effective on-chip

integration. Electro-optical control of light on [[silicon]] is challenging owing to its weak electro-optical properties. The large dimensions of previously demonstrated structures were necessary to achieve a significantsignificant modulation of the transmission in spite of the small change of refractive index of silicon. Liu et al. have recently demonstrated a high-speed silicon [[optical modulator]] based on a metal–oxide–semiconductor (MOS) configurationconfiguration.<ref>Liu, A. et al. Nature 427, 615–618 (2004)</ref> Their work showed a high-speed optical active device on silicon—a critical milestone towards [[optoelectronic]] integration on silicon.

== Electro-optic modulator of nano-structures ==

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== Magneto-optic modulator of nano-structures ==

A dc magnetic field Hdc is applied perpendicular to the light propagation direction to produce a single ___domain, transverse directed 4~Ms. The rf modulation field Hrf, applied by means of a coil along the light propagation direction, wobbles 4~Ms through an angle of @ and produces a time varying magnetization component in the longitudinal direction. This component then produces an ac variation in the plane of polarization via the longitudinal Faraday effect. Conversion to [[amplitude modulation]] is accomplished by the indicated analyzer.

[[File:optical mod2.jpg]]

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MODULATION OF THz RADIATION BY SEMICONDUCTOR NANOSTRUCTURES<ref>MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 35, No. 5, December 5, 2002</ref>

As a result of increased demand for bandwidth, wireless short-range communication systems are expected to extend into the THz frequency range. Therefore, the fundamental interactions between THz radiation and semiconductors are receiving increasing attention. This new quantum structure is based on the well-established technology for producing high electron mobility transistors where an electron gas is confinedconfined at a GaAs/AlxGa1 xAs interface. The electron density at the hetero-interface can be controlled by the application of an external gate voltage, which in turn will alter the transmission/reflection characteristics of the device to an incident THz beam.

== Applications and Commercial products ==