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PLASMONICS A NEW DEVICE TECHNOLOGY PRESENTED BY: C . Deepika Kameswari R. Nikhila Reddy [email protected] [email protected] ECE III/IV (II-SEM) ECE III/IV (II-SEM) Contact no.: 9985387080 C M R COLLEGE OF ENGG. & TECHNOLOGY PLASMONICS – THE NEXT DEVICE TECHNOLOGY fixed positive ions with a plasma frequency. Abstract: Plasmonics, Electronic circuits provide us with the ability to control the transport and storage of electrons. However, the performance of electronic circuits then, is the technology of transmitting these lights like waves along nanoscale wires. With every wave, we can, in principle, carry loads of information. is now becoming rather limited when digital information needs to be sent from one point to another. Photonics offers an effective solution to this problem by implementing optical communication systems based on optical fibers and photonic circuits. Unfortunately, the micrometer-scale bulky components of photonics have limited the integration of these components into electronic chips, which are now measured in nanometers. Surface plasmon–based circuits, which merge electronics and photonics at the nanoscale, may offer a solution to this sizecompatibility problem. Here we review the current status and future prospects of plasmonics Thus development of chip-scale electronics and photonics has led to remarkable data processing and transport capabilities that permeate almost every facet of our lives. Plasmonics is an exciting new device technology that has recently emerged. It exploits the unique optical properties of metallic nanostructures to enable routing and manipulation of light at the nanoscale. A tremendous integrating synergy can plasmonic, be attained electronic, by and conventional dielectric photonic devices on the same chip and taking advantage of the strengths of each technology. in various applications including plasmonic chips, light generation, and nanolithography. Introduction: The term Plasmonics is derived from ‘plasmons’, which are the quanta associated with longitudinal waves propagating in matter through the collective motion of large numbers of electrons. Plasma is a medium with equal concentration of positive and negative charges, of which at least one charge type is mobile. In as solid, the negative charges of the conduction electrons are balanced by an equal concentration of positive charge of the ion cores. A plasma oscillation in a metal is a collective longitudinal excitation of the conduction electron gas against a background of The ever-increasing demand for faster information transport and processing capabilities is undeniable. Our data-hungry society has driven enormous progress in the Si electronics industry and we have witnessed a continuous progression towards smaller, faster, and more efficient electronic devices over the last five realize decades. The scaling of these devices has also processing speeds. The metals commonly used in brought about a myriad of challenges. Currently, electrical interconnection such as Cu and Al two of the most daunting problems preventing allow the significant increases in processor speed are polaritons (SPPs). SPPs are electromagnetic thermal and signal delay issues associated with waves that propagate along a metal-dielectric electronic interconnection. Optical interconnects, interface and are coupled to the free electrons in on the metal. the other hand, possess an almost the dream of excitation of significantly surface faster plasmon- unimaginably large data carrying capacity, and may offer interesting for From an engineering standpoint, an SPP can be Optical viewed as a special type of light wave. The alternatives may be particularly attractive for metallic interconnects that support such waves future chips with more distributed architectures thus serve as tiny optical waveguides termed in which a multitude of fast electronic computing plasmonic waveguides. The notion that the units (cores) need to be connected by high-speed optical mode (‘light beam’) diameter normal to links. Unfortunately, their implementation is the metal interface can be significantly smaller hampered by the large size mismatch between than the wavelength of light has generated electronic and dielectric photonic components. significant excitement and sparked the dream Dielectric photonic devices are limited in size by that one day we will be able to interface the fundamental laws of diffraction to about half nanoscale electronics with similarly sized optical a wavelength of light and tend to be at least one (plasmonic) devices. It is important to realize or two orders of magnitude larger than their that, with the latest advances in electromagnetic nanoscale electronic counterparts. This obvious simulations and current complementary metal- size mismatch between electronic and photonic oxide components presents a major challenge for fabrication techniques, a variety of functional interfacing these technologies. Further progress plasmonic structures can be designed and will require the development of a radically new fabricated in a Si foundry right now. Current Si- chip-scale device technology that can facilitate based integrated circuit technology already uses information transport between nanoscale devices nanoscale metallic structures, such as Cu and Al at optical frequencies and bridge the gap between inter-connects, the between transistors on a chip. This mature circumventing world these of new solutions problems. nanoscale electronics and microscale photonics. semiconductor to route (CMOS)-compatible electronic signals processing technology can thus be used to our advantage in integrating plasmonic devices with Plasmonics as a new device technology their electronic counterparts. In and some dielectric cases, photonic plasmonic Metal nanostructures may possess exactly the waveguides may even perform a dual function right combination of electronic and optical and simultaneously carry both optical and properties to tackle the issues outlined above and electrical signals, giving rise to exciting new nano-structured materials must be used to capabilities. fabricate effective plasmonic devices. For this reason, plasmonics is frequently associated with nanotechnology. Plasmonics describes how ultra-small metallic structures of various shapes capture and manipulate light and provides practical design tool for nanoscale optical components. The fact that light interacts with nanostructures overcomes the belief held for more than a century that light waves couldn’t interact with anything smaller than their own wavelengths. Fig (a) the red arrow shows how an SPP is launched from an excitation spot onto a metal film surface. When light of a specific frequency strikes a plasmon that oscillates at a compatible frequency, the energy from light is harvested by the plasmon, converted into electrical energy that Plethora of Benefits: propagates Plasmon waves through the nanostructure and eventually converted back into light. are of particular interest these because are at Limitations do exist! The optical plasmonics frequencies. The higher now the the frequency of today’s electronic microprocessors. right mainly that plasmons can wave, the more frequencies are about 100,000 times greater than is of limited by the fact frequency of the the information we can transport. Optical potential typically travel only several millimeters before they peter out. Chips, meanwhile, are typically about a centimeter across, so plasmons can’t yet go the whole distance. The distance that a plasmon can travel before dying out is a function The key is using a material with a low refractive index, ideally negative, such that the incoming electromagnetic energy is reflected parallel to the surface of the material and transmitter along its length as far as possible. There exists no natural material with a negative refractive index, so of several aspects of the metal. But for optimal transfer through a wire of any metal, the surface of contact with surrounding materials must be as smooth as possible and the metal should not have any impurities. For most wavelengths of visible light, aluminum Plasmonics has also been used in biosensors. allows plasmons to travel farther than other When a particular protein or DNA molecule rests metals such as gold, silver and copper. It is on the surface of a plasmon-carrying metallic somewhat ironic that aluminum is the best metal material, it leaves its characteristic signature in to use because the semiconductor industry the angle at which it reflects the energy. recently dumped aluminum in favor of copper – the better electrical conductor – as it is wiring of In the field of chemical sensing plasmonics choice. Of course, it may turn out that some kind offers the possibility of new technologies that of alloy will have even better plasmonic will allow Doctors, anti-terror squads and properties than either aluminum or copper. environmental experts to detect chemicals in quantities as small as a single molecule. Another classic semiconductor issue that the researchers will have to address is ‘heat’. Conclusions: Chipmakers are constantly striving to ensure that Plasmonics has their electronic chips don’t run too hot. the potential to Plasmonics also will generate some heat, but the play a unique exact amount is not yet known. Even if and important plasmonics runs as hot as electronics, it will still role in have the advantage of higher data capacity in the enhancing same space. processing Promising applications: speed of future Before all- plasmonic chips the integrated circuits. The field has witnessed an explosive growth over the last few years and our are developed, knowledge base in plasmonics is rapidly expanding. As a result, the role of plasmonic plasmonics will probably be integrated with devices on a chip is also becoming more well- conventional silicon devices. Plasmonic wires defined. In the past, devices were relatively slow will act as high band-width freeways across the and bulky. The semiconductor industry has busiest areas of the chip. Plasmon printing is a performed an incredible job in scaling electronic new approach to lithographic printing that takes devices to nanoscale dimensions. Unfortunately, advantage of the resonantly enhanced optical interconnect delay time issues provide significant intensity in optical near-field of metallic nano- challenges toward the realization of purely particles, and that could enable printing of deep electronic circuits operating above ~10 GHz. In sub-wavelength features using conventional stark contrast, photonic devices possess an photo-resist and simple visible ultra-violet light enormous data-carrying capacity (bandwidth). sources. Unfortunately, dielectric photonic components are limited in their size by the laws of diffraction, preventing the same scaling as in electronics. Finally, plasmonics offers precisely what electronics and photonics do not have: the size of electronics and the speed of photonics. Plasmonic devices, therefore, might interface naturally with similar speed photonic devices and similar size electronic components. For these reasons, plasmonics may well serve as the missing link between the two device technologies that currently have a difficult time communicating. By increasing the synergy between these technologies, plasmonics may be able to unleash the full potential of nanoscale functionality and become the next wave of chipscale technology. Acknowledgements: Articles from website http://www.sciencedaily.com Articles from website http://www.wisegeek.com Plasmonic technology and its applications by Dr S S Verma, professor in Dept of Physics, SLIET, Longolwal, Punjab Plasmonics, the next chip-scale technology – Rashid Zia, Anu Chandran and Mark L Brongersma from Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California USA End of Document