Apresentação em tema: "Resumo anterior Modulação"— Transcrição da apresentação:
1Resumo anterior Modulação Eletromecânica – chopperEletro-ópticaEfeito PockelEfeito KerrMagneto-ópticaEfeito FaradayMagneto-KerrAcusto-ópticaReflexão de Bragg, célula de BraggXstal de quartzo, PZTFotolitografia. Demo de materias p/ fotolitografia: placa cobreadas de fenolite, fibra de vidro, face simples , face duplas. Fotolito.Litografia
8A colocação de água aumenta a NA (nsenq) Litografia de imersãoLimite de resolução para litografia é usando a eq de Rayleigh:W é a largura da linha impressa.Onde k1 é o fator de resolução, l é o comprimento de onda da radiação de exposição e NA é a apertura numérica.Immersion lithography Stepper resolution is normally expressed as W = R = k (process coefficient) x lambda (light source wavelength) / NA (numerical aperture; the brightness of the projection lens). The shorter the wavelength of the light source and the higher the NA of the lens, the higher the resulting resolution. NA itself is expressed as n x sin theta, where n is the refractive index of the material through which the light passes, and theta is the angle of incidence of that light. Normally this light beam passes through air, meaning that n = 1. In immersion lithography, however, a liquid with a refractive index of greater than 1 is placed between the projection lens and the wafer, resulting in a corresponding increase in the NA of the system. For a given incident angle theta, minimum feature size can be reduced (improved) to 1/n. For a given NA theta can be reduced, allowing the focal depth to be increased n times. If an ArF laser is used as the light source, distilled water with a refractive index of 1.44 is placed between the projection lens and the wafer. This technique has been used for some time in microscopes.A colocação de água aumenta a NA (nsenq)
9Litografia de imersãoThe most recent SEMATECH-led Litho Forum, an invite only event for around 100 of the top lithography experts in the semiconductor industry are reported to have confirmed that they expect 193nm ArF immersion lithography to pattern critical layers at the 45nm half-pitch node in 2009 as well as continue at the 32nm half-pitch "The surveys indicated an aggressive adherence to the half-pitch targets identified by the International Technology Roadmap for Semiconductors (ITRS)," said Michael Lercel, SEMATECH Lithography director and conference chair. "However, cost concerns for new approaches are in the forefront of many people's minds." Immersion lithography is a technology in which lithographic exposure of a resist coated wafer is performed with purified water introduced between the projection lens of a stepper and the wafer. The light source of the leading-edge stepper currently used in production lines is the ArF 193nm excimer laser, and the resolution is approximately 90nm. 65nm is said to be the limit even for a system for research and development. The idea behind immersion lithography is to use the same ArF light source and yet realize a semiconductor process technology that achieves a resolution higher than 65nm.================================================================================================= This is in respect to double patterning that could be necessary at the 32nm node should EUV Lithography not be ready for volume production in that time frame. EUVL was deemed the only choice at the 22nm node as concerns have arisen over the extendibility of immersion to higher NA's that will require higher index fluids and lenses. Although other technologies such as maskless lithography and nano-imprinting technology were reviewed at the forum, it would seem that optical lithography will continue to be the preferred choice through to the 22nm node.
10Evolução da largura de linha mínima e l O fator de resolução k1 é um fator complexo que depende de várias variáveis no processo de fotolitografia: qld do fotoresist, técnicas de melhoramento da resolução, tipo de mascaras, tipo de iluminação, entre outros.
11Evolução de NA e k1 G-line => 436nm I-line => 365nm Laser de ArF=> 193 nmg-lineAn emission line of the mercury discharge lamp centered about 436nm.In the visible portion of the EM spectrum.First generation of lithography tools used this emission line for photoresist exposure.Yields resolution of 1um in resist. See Description of Rayleigh equation for discussion on resolution dependence on wavelength.i-lineAn emission line of the mercury discharge lamp centered about 365nm.Second generation of lithography tools used this emission line for photoresist exposure.In the ultraviolet portion of the EM spectrum.Yields resolution of 0.5um in resist. See Description of Rayleigh equation for discussion on resolution dependence on wavelength.
12Imersão numerical aperture the product of the lowest index of refraction in the object space multiplied by the sine of half the angular aperture of the objective.numerical aperture (NA)For a microscope, (the half angle of the cone of light accepted by the objective lens) x (refractive index of the medium between the specimen and the lens). Also similarly for the cone of light emerging from the condenser lens.The numerical aperture of a lens system (objective or condenser). It is the sine of one-half the angular aperture times the refractive index of the medium (1.0 for air, for Cargille immersion oil, etc.) between objective and specimen. The numerical aperture is a measure of the light gathering capacity of the lens system and determines its resolving power and depth of field.
13Existem vários tipos de processos litográficos Feixe de elétronsEUVSPLRaio-XMas
22Independente da forma como é realizada.... Observar o produto final objetivo dos efeitos que desejamos
23Óptica integradaDesenvolvimento de dispositivos ópticos miniaturizados, em escala de micro – nano, de alta funcionalidade sobre substratos.Nesta área é possível distinguir:Circuitos ópticos integrados. A luz é confinada em guias de onda de filmes finos, depositados ou cavados no substrato (vidro, xstal dielétrico, semicondutor).Dispositivos ópticos planares
24Canais de guia de onda fio de cobre As guias de onda são feitas pordeposição de material sobre o topo dosubstrato e posteriormente atacadoquimicamente para retirar o restodo material. Pode ser ao contrário tb,Fazendo os sulcos por ataque químicoe posteriormente preenchido commaterial da guia de ondaCondições: índice de refraçãomaior na guia do resto domaterial.
26Guia de onda em LiNbO3Tiras de Ti depositado no padrão de guia de onda desejado sobre substrato de LiNbO3 puroAquecimento => difusãoObtenção de guia de onda semicircular6 Lithium NiobateThe substrate is single-crystal lithium niobate, and the waveguides are usually part of the substrate with indiffused titanium. Lithium niobate has relatively low propagation loss in the telecommunications band (-0.2 dB/cm) yet has extremely high linear electrooptic coefficients (it is acentric). It can provide very fast and efficient phase shifters and polarization converters.The most common LiNbO3 waveguide is the Ti-diffused waveguide. lo7 Onto a substrate of LiNb03 (pure crystal), Ti strips are deposited in the desired waveguide pattern. Then the device is heated, and the Ti diffuses into the LiNb03 making a semicircular waveguide. This core is not buried, so care must be taken to keep electrodes on top from absorbing the light. The typical waveguide structure is shown in Fig. 53.Vol. 5, No. 2/February 1988/J. Opt. Soc. Am. B
27Phase ShifterA mudança de fase vem unicamente do efeito Pockels, campo elétrico provocado através dos dois fios de ouro, que fazem a mudança do índice de refração. Tem sido obtidos moduladores de até 40Gb/s.The phase shift arises solely from the Pockels effect. One simply places twogold lines, around the waveguide (see Fig. 54). The electric field then changesthe refractive index. 40 Gb/s modulators have been demonstrated.6.3 DIGITAL SWITCHOne can make a digital 2 x 2 switch in LiNb03 by placing electrodes on thewaveguides with the same width in an adiabatic coupler (see Sec 2.10).108W henno voltage is applied, the coupler acts as a 50/50 coupler, as expected. Whena voltage is applied to one waveguide, the switch is in either a bar or crossstate, and vice versa with application to the other waveguide. Once sufficientvoltage is applied to make the two waveguides no longer identical, a furtherincrease in voltage does not further affect the switching. Such switches havebeen combined in fabrics to make fully integrated spatial cross connects aslarge as 16 x 16.'09
28SAW = Surface Acoustic Wave Dispositivos acusto-ópticos são fabricados por processos fotolitográficosTipicamente consiste de dois conjuntos de transdutores interdigitais.Um transdutor converte a energia do sinal elétrico em energia mecânica ondulatória.O outro transdutor faz o processo reverso.A surface acoustic wave (SAW) is an acoustic wave traveling along the surface of a material having some elasticity, with an amplitude that typically decays exponentially with the depth of the substrate. This kind of wave is commonly used in piezoelectric devices called SAW devices in electronics circuits. SAW devices are employed as filters, oscillators and transformers based on the transduction of acoustic waves.Electronic devices employing the SAW normally utilize one or more interdigital transducers (IDTs) to convert acoustic wave to electrical signal and vice versa utilizing the piezoelectric effect of certain materials (quartz, lithium niobate, lithium tantalate, LGS etc). These devices are fabricated utilizing common processes used in the manufacture of silicon integrated circuits.SAW filters have enjoyed successful application in the booming cellular telephones market and provide significant advantages in performance, cost, and size over other filter technologies (digital signal processors, quartz crystals (bulk wave) , LC-filters, and waveguide filters).Significant research has been done in the last 20 years in the area of surface acoustic wave sensors. Sensor applications include all areas of sensing (such as chemical, optical, thermal, pressure, acceleration, and biological). SAW sensors have seen limited commercial success, but are commonly commercially available for some applications such as touchscreen displays.6.4 A COUSTOOPTIC FILTERA device that has both optical and acoustic waveguides is the acoustoopticfilter in LiNbO3. LiNb03 waveguides have different effective indices forTE- and TM-polarized light. However, by applying an acoustic wave overthe waveguide, the periodic nature of the wave can cause the TE and TMlights to be phase-matched at a certain wavelength. Then a diagonal-orientedbirefringence becomes significant, causing polarization conversion at thatwavelength.One way to couple the acoustic wave to the LiNb03 is to use a surface acousticwaveguide, made up of a thin film of a transparent material such as Si02or In203-doped SiO2."O So if one makes such an acoustic waveguide over anoptical waveguide and launches a traveling acoustic wave with a transducer, thepolarization in the optical waveguide will be converted at a certain wavelength.The wavelength response will have large sidelobes, however, without apodization.Apodization can be accomplished by tilting the acoustic waveguide withrespect to the optical waveguide.The polarization-converted light is, unfortunately, Doppler-shifted by theacoustic wave. One way to avoid this is to have the shifted light pass throughanother acoustic wave that is traveling in the opposite direction, in a secondstage. Several stages must be used to achieve low crosstalk anyway.One can launch a sum of acoustic frequencies in the waveguide makinga series of filters, such as for dropping multiple channels in a WDM system.When there is only acoustic frequency, then light that was polarizationconverted and Doppler shifted has the opposite Doppler shift if it happensto couple back into the original field. However, with multiple acoustic frequencies,polarization-converted light could be Doppler shifted back into theoriginal field with a different Doppler shift, resulting in intensity beating noise.Figure 55 shows the waveguide layout and filter characteristics of an adddropmade using acoustooptic polarization converters.Figure 1. Acoustic wave devices are manufactured by means of a photolithographic process similar to that used to make ICs. The only difference is that no junction exists in acoustic wave sensors.
29Diferentes arranjos dos eletrodos IDT =InterDigital TransducerSOME UNUSUAL PROPERTIES OF SAW DEVICES Question 2: Before we go any further, tell me if surface acoustic wave (SAW) filters are analog or digital devices? Answer 2: Tricky question! My own view is that some configurations (as in the basic bidirectional interdigital transducer (IDT) structure of Figure 1), can be considered to operate as passive HYBRID analog/digital devices! The basic SAW filter sketched in Figure 1 is indeed a passive analog device. It is just a thin metal film structure deposited on top of a piezoelectric crystal substrate, with no power supplies to worry about. However, this is not the complete answer! Now for the digital part. Look at the constituent input/output IDTs. The layout pattern of these input/output thin metal film patterns is designed to provide the desired bandpass filtering function H(f) = Voutput/Vinput as the SAW propagates along the piezoelectric crystal surface. But these bidirectional IDTs may be considered to act as spatially-sampled versions of the corresponding time-evolving Inverse Discrete Fourier Transform (IDFT) h(t). (Remember that there is a unique correspondence between the frequency response H(f) of a filter, and its impulse response h(t). (Simple concepts for digital signal-processing engineers. Not so simple for old analog circuit designers like me !). Because of this, many digital signal processing techniques can be employed in the design of the IDT patterns. Additionally, SAW filters find applications in many digital communications systems.Question 4: Can SAW bandpass filters operate at harmonic frequencies? Answer 4: Yes. They can operate at selected harmonic frequencies, depending on the metalization ratio h = a/b in Figure 2. Rayleigh-wave delay-line filters employing split-electrode IDTs on YZ-lithium niobate have been reported as operating efficiently up to the 11th harmonic. (See: W. R. Smith, "Basics of the SAW interdigital transducer," in J. H. Collins and L. Masotti (eds.) Computer-Aided Design of Surface Acoustic Wave Devices. Elsevier: New York, Also see: W. R. Smith and W. F. Pedler, "Fundamental- and harmonic-frequency circuit model analysis of interdigital transducers with arbitrary metalization ratios and polarity sequences," IEEE Transactions on Microwave Theory and Techniques, vol. MTT-23, pp , November 1975). The IDTs in Figure 2(a) and Figure 2(b) can operate at selected odd-harmonic frequencies, while the IDT structure in Figure 2(c) can operate at selected even and odd harmonics, depending on the metalization ratio.
30SAW http://kmf.pa.msu.edu/Research/resrch01.asp Probing Disordered Metallic Films With Surface Acoustic WavesAmy Bylsma Engebretson and Brage GoldingDepartment of Physics and Astronomy, Michigan State UniversityA surface acoustic wave (SAW) can be generated and received by interdigital electrodes, or metal fingers, deposited onto a piezoelectric slab. A SAW is a sound wave which travels along the surface of a solid. Its wavelength is determined by the spacing of the fingers. The above SEM micrograph shows aluminum fingers on lithium niobate. The finger spacing of 1.36 micron (about inches) corresponds to the wave oscillating at frequencies near 700 MHz. By placing thin films of disordered metals in the path of the SAW, we can probe the interaction of the waves with the electrons and defects in the metal. At very low temperatures, near absolute zero, atoms that comprise the defects can absorb energy from the waves and move between two nearby positions. We are studying the characteristics of these transitions in order to arrive at a better understanding of the interactions between defects and electrons.
31SAW+fibra = demux = dispositivo integrado Conversor de polarização acusto-ópticoThe integrated acoustooptical polarization converter is one of the basic building blocks of the acoustooptical device family. The function of the converters is based on a wavelength selective coupling between orthogonally polarized optical waves induced by surface acoustic waves. Such surface acoustic waves (SAW) are a kind of ultrasound waves confined close to the surface of the crystal. The surface acoustic waves induce a periodic distortion for the optical waves resulting in a polarization conversion. An efficient process requires a coherent accumulation of the conversion along the interaction path. Therefore, the phase-matching condition must be fullfilled: The difference of the wave numbers of the optical waves must be compensated by the wave number of the SAW. This requirement leads to the wavelength selectivity of the conversion process. Via the frequency of the SAW the wavelength for optimum conversion can be adjusted.Devices are usually fabricated to operate in the 1.55 µm range for telecommunication applications. Phase-matching is obtained with SAW frequencies around 170 MHz and the tuning slope is given by about 8 nm/MHz.To enhance the efficiency of the polarization conversion surface acoustical waves can be laterally confined in guiding structures as well. For this purpose acoustical waveguides and even complexer structures such as directional couplers are fabricated. Such acoustical guides are formed by a Ti-indiffusion into the cladding regions of the guiding structures. Due to this indiffusion the stiffness of the material and, hence, the acoustical velocity increases yielding the guiding of the SAWs.Practically, acoustooptical polarization converters are most often realized by embedding a Ti-indiffused optical waveguide into an acoustical waveguide which forms one arm of a directional coupler. A SAW wave is excited via a RF-signal applied to the interdigital transducer electrodes. While propagating along the coupler structure the acoustic power is coupled into the adjacent guide with the embedded optical waveguide. A detailed study of such integrated acoustical structures has been performed to determine optimum coupler dimensions. By an appropriate choice of the waveguide dimensions the SAW fullfills exactly one coupling cycle within the structure.The main advantage of such polarization converters with acoustical directional couplers is an improvement of the spectral characteristics of the conversion process: The conversion characteristics of polarization converters with unguided SAWs or with SAWs guided in straight acoustical guides have pronounced sidelobes. Theoretically, these sidelobes should be about -10 dB below the maximum conversion. To apply the acoustooptical devices as spectral filters for instance in WDM transmission systems such sidelobes are not acceptable. The sources for the sidelobes are the abrupt increase and decrease of the acoustooptical interaction at the transducer and absorber, respectively. With a soft increase and decrease the sidelobes can be tremendously reduced. Such a weighted (apodized) coupling is realized using the directional coupler as the acoustical power is continuously coupled into the interaction region and back again.Typical acoustooptical polarization converters are about 20 mm long. The spectral width (full-width at half maximum) is about 2.0 nm. Sidelobe levels are typically reduced to about -20 dB of the maximum conversion using acoustical directional couplers. RF-drive powers for a complete acoustooptical conversion are in the range of 50 mW. The tuning range is determined by the frequency bandwidth of the transducers to excite the SAWs. Typical tuning ranges exceed 150 nm. However, more than 250 nm has been demonstrated.A special unique feature of the acoustooptical polarization converters is their simultaneous multi-wavelength operation capability. By exciting several SAWs of different frequencies in the converter, conversion is obtained at several wavelengths simultaneously, too.Related publications:J. Frangen, H. Herrmann, R. Ricken, H. Seibert, W. Sohler Integrated optical, acoustically tunable wavelength filter Electron. Lett., Vol. 25, pp (1989)H. Herrmann, St. Schmid Integrated acoustooptical mode converters with weighted coupling using surface acoustic wave directional couplers Electron. Lett, Vol. 28, pp (1992)H. Herrmann, U. Rust, K. Schäfer Tapered acoustical directional couplers for integrated acoustooptical mode converters with weighted coupling J. Lightw. Technol., Vol.13, pp (1995)H. Herrmann, H. Mendis Broadly tunable integrated acoustooptical polarization converters in LiNbO3 Proc. 9th European Conference on Integrated Optics (ECIO'99), Torino, April 1999, pp
32Filtros TE e TM Y2O3 = 17nm Al = 100nm Comprimento = 1,5mm extinção 20dB TM e 0,5dB atenuação TETroca de Li por HRegião H aumenta neno diminuiTE se acopla na região H, extinção 25dBTM atenua 1dBAcoustooptical Devices Integrated TE- and TM-pass polarizersPolarizers are basic building blocks for the integrated acoustooptical devices. Two types of integrated polarizers are required: TE- and TM-pass polarizers. These polarizers are used to suppress one polarization component propagating in an optical waveguide. In conventional optics several types of polarizers are well-known. Integrated polarizers, however, must be compatible with the specific waveguiding structure.TE-pass polarizers The basic structure of a TE-pass polarizer consists of a sandwich layer system on top of the waveguide structure. This layer system is formed of a dielectric layer (yttrium oxide) followed by an absorbing metallic layer (aluminium). TM-polarized radiation is coupled to surface plasmons of the metallic layer resulting in a strong absorption. On the other hand, TE polarized optical waves are not strongly influenced by the layer system.Best performance properties have been obtained with 17 nm thick yttrium oxide layers and 100 nm thick aluminium layers. In 1.5 mm long structures extinctions of the TM-waves exceeding 20 dB have been achieved. The excess loss for the TE-polarized waves could be kept below 0.5 dB.TM-pass polarizers TM-pass polarizers are fabricated using the proton exchange technique in lithium niobate, i.e. lithium ions of the crystal are substituted by hydrogen ions. The extraordinary index of refraction is increased in the proton exchanged regions and the ordinary index is reduced. TM-pass polarizers are realized by using proton exchanged areas beside the Ti-diffused optical waveguides. In this way the extraordinary polarized (TE) waves couple into the exchanged areas whereas ordinary polarized (TM) waves remain in the Ti-diffused optical waveguide.To optimize TM-pass polarizers careful studies were necessary to investigate the profiles of the refractive indices in proton exchanged lithium niobate and to study the geometry of proton exchanged areas. We found that two major effects determine the polarizer performance: the gap between Ti-diffused optical guide and exchanged regions and the shape of the proton exchanged areas. A narrow gap results in a large extinction but also induces strong additional losses for the TM-waves. Therefore, a compromise has to be found. On the other hand the geometry of the outer boundaries determines the extinction ratio. If parts of the TE-waves are reflected at the outer boundaries they can be recaptured into the optical waveguides resulting in a low extinction ratio. With zig-zag shaped outer boundaries the best performance has been achieved. With such optimized polarizers extinction ratios of more than 25 dB for the TE-waves and excess losses of about 1 dB for the TM-polarized waves have been obtained.Related publications:H. Herrmann, P. Müller-Reich, V. Reimann, R. Ricken, H. Seibert, W. Sohler Integrated optical, TE- and TM-pass, acoustically tunable double stage wavelength filter in LiNbO3 Electron. Lett., Vol. 28, pp (1992)F. Tian, Ch. Harizi, H. Herrmann, V. Reimann, R. Ricken, U. Rust, W. Sohler, F. Wehrmann, S. Westenhöfer Polarization independent integrated optical, acoustically tunable double stage wavelength filter in LiNbO3 J. Lightwave Technol., Vol. 12, pp (1994)U. Hempelmann, H. Herrmann, G. Mrozynski, V. Reimann, W. Sohler Integrated optical proton exchanged TM-pass polarizers in LiNbO3: modelling and experimental performance J. Lightwave Technol. , Vol. 13, pp (1995)If this page is displayed without a button frame on the left side, please reload.Last update: H. Herrmann
33Materiais eletro-ópticos Table 1. Electro-Optic MaterialsMaterialAbbreviationChemical FormulaTransmission Range (mm)Bandwidth (MHz)Index of Refraction no,ne at wavelength (mm)Ammonium dihydrogen phosphateADPNH4H2PO4to 5001.51, 1.47 at 1.06Potassium dihydrogen phosphateKDPKH2PO4> 1001.51, 1.47 at 0.55Potassium dideuterium phosphateKD*PKD2PO4to 3501.49, 1.46 at 1.06Lithium niobateLNLiNbO3to 80002.23, 2.16 at 1.06Lithium tantalate—LiTaO3to 10002.14, at 1.00Cadmium tellurideCdTe2 - 16no = 2.6 at 10
34Table 2. Acousto-Optic Materials Material Chemical formula Spectral range (mm)Figure of merit M2 ( m2/W)Bandwidth (MHz)Typical drive power (W)Index of RefractionAcoustic Velocity (m/sec)Fused silica/quartzSiO21.6to 2061.46 (634,3 nm)5900Gallium arsenideGaAs104to 35013.37 (1.15 mm)5340Gallium phosphideGaP45to 1000503.31 (1.15 mm)6320GermaniumGe840to 54.0 (10.6 mm)5500Lead molybdatePbMoO4to 501 - 22.26 (633 nm)3630Tellurium dioxideTeO235to 3004200Lithium niobateL6Nb030.5-27> 30050-1002.20 (633nm)6570
35DispositivosPodem ser fabricados sobre substratos planares usando processos litográficos comuns e tecnologia de filmes finos.Litografia por feixe de elétrons ou por laserMétodos epitaxiais para fabricação de fontes, detectores e circuitos opto-eletrônicos.AsGa, Si, InPramificação
36Acoplamentos Acopladores direcionais como ramificadores por acoplamento de ondas evanescentesentre acopladores adjacentesAcoplador por reflexão de Bragg
37Interferômetro Mach-Zehnder ChaveamentoInterferômetro Mach-ZehnderAquecedor (ms) ou onda acústica (piezo) (ms) ou sinal elétrico num dos braços
38Outro tipo de chaveamento Integrated electro-optic Mach-Zehnder switch realizedby Zinc in-diffusionD. A. May-Arrioja and P. LiKamWaCollege of Optics and Photonics, University of Central Florida, Orlando, FL5th Iberoamerican Meeting on Optics and 8th Latin American Meeting on Optics, Lasers,and Their Applications, edited by A. Marcano O., J. L. Paz, Proc. of SPIE Vol. 5622(SPIE, Bellingham, WA, 2004) · X/04/$15 · doi: /
51Processo de photoresist para litografia SCUM = a film or layer of foul or extraneous matter that forms on the surface of a liquid.DESCUM = limpeza de qq resíduo pelicular existente ou melhor: lavagem
54Fontes de luz em litografia G-line nmI-line nmKrF Excimer nmArF Excimer nmEUV < 13nmg-line A light source used in the repeated exposure of a mask pattern in the photolithography process, with the objective of transferring the pattern to the surface of a wafer. Classified as visible light, g-line light has a wavelength of 436nm and is used to resolve patterns of 0.5 microns or larger. Steppers employing this light are called g-line steppers.i-line A light source used in the repeated exposure of a mask pattern in the photolithography process, with the objective of transferring the pattern to the surface of a wafer. Classified as ultraviolet light, i-line light has a wavelength of 365nm and is used to resolve patterns of 0.25 to 0.5 microns. Steppers employing this light are called i-line steppers.
56Materiais Fotônicos Dispositivos Fotônicos Cristais Fotônicos Algumas referenciasCid Araujo, Óptica Não-linear. VIII Escola J.A. Swieka 2002
57FotônicaCiência e tecnologia baseada em e relacionada com o controle e processamento de radiação eletromagnética, fóton de luz, incorporando óptica – eletrônica - ciência dos materiais – laser – memória – processamentos.É o equivalente óptico da eletrônica
65Trabalhar em qq sala? Sala limpa Qualidade, temperatura e unidade do ar altamente controlada para evitar contaminação, e.g.:Centros cirúrgicos (aquela estória de infecção hospitalar)Laboratórios de processamentos litográficosRemoção de partículas e impurezas, inclusive bactérias, através de processos de filtragemClassificação de Sala Limpa:Americano: Federal Standard 209Europeu: ISOA work area in which the air quality, temperature and humidity are highly regulated in order to protect sensitive equipment from contamination. Clean rooms are important features in the production of silicon chips, hard disk drives and other technologies such as satellites. The air in a clean room is repeatedly filtered to remove dust particles and other impurities that can damage the production of highly sensitive technologies. The measure of the air quality of a clean room is described in Federal Standard 209. Clean rooms are rated as "Class 10,000," where there exists no more than 10,000 particles larger than 0.5 microns in any given cubic foot of air; "Class 1000," where there exists no more than 1000 particles; and "Class 100," where there exists no more than 100 particles. Hard disk drive fabrication requires a Class 100 clean room.People who work in clean rooms must wear special protective clothing called "bunny suits" that do not give off lint particles and prevent human skin and hair particles from entering the room's atmosphere.
66Classes de sala limpa, padrão Americano Número máximo de partículas no ar (partículas por pé cúbico de ar)ClasseTamanho da Partícula0.1 μm0.2 μm0.3 μm0.5 μm5.0 μm1357.531035075301007503001,000710,00070100,000700
67Classes de sala limpa, padrão ISO Número de partículas por metro cúbico por tamanho micrométrico0.1 um0.2 um0.3 um0.5 um1 um5 umISO 1102ISO 2100244ISO 31,000237102358ISO 410,0002,3701,02035283ISO 5100,00023,70010,2003,52083229ISO 61,000,000237,000102,00035,2008,320293ISO 7352,00083,2002,930ISO 83,520,000832,00029,300ISO 935,200,0008,320,000293,000
68Outras normas ISO para sala limpa ISO DocumentTitleISOClassification of Air CleanlinessISOCleanroom Testing for ComplianceISOMethods for Evaluating & Measuring Cleanrooms & Associated Controlled EnvironmentsISOCleanroom Design & ConstructionISOCleanroom OperationsISOTerms, Definitions & UnitsISOEnhanced Clean DevicesISOMolecular ContaminationISOBiocontamination: Control General PrinciplesISOBiocontamination: Evaluation & Interpretation of DataISOBiocontamination: Methodology for Measuring Efficiency of Cleaning Inert Surfaces
70Outra representação dos tamanhos HEPA = high efficiency particulate airA high efficiency particulate air, or HEPA (pronounced /ˈhɛpə/), filter is a type of high-efficiency air filter.What is HEPA Filtration?HEPA filtration was developed by the Atomic Energy Commission during World War II to remove radioactive particles from the air in manufacturing plants.Definition of HEPA FilterA HEPA filter must remove at least 99.97% of all airborne particles by particle count at a size of 0.3 microns which is one-300th the diameter of a human hair. It approaches total efficiency on all known organisms harmful to man.Common Uses for HEPA FiltersIn hospital operating rooms, burn centers, laboratories and manufacturers of critical products like computer chips, where particle and bacteria free air is mandatory, HEPA filtration systems are used to remove bacteria and other airborne contaminants.Filters are Maintenance FreeHEPA filters require no cleaning or maintenance to maintain efficiency, and studies have proven that HEPA filters actually increase in efficiency with use over their 3 to 5 year life.
80MEMS = Micro Electro Mechanical System Micro-Electro-Mechanical Systems (MEMS) is the integration of mechanical elements, sensors, actuators, and electronics on a common silicon substrate through microfabrication technology. While the electronics are fabricated using integrated circuit (IC) process sequences (e.g., CMOS, Bipolar, or BICMOS processes), the micromechanical components are fabricated using compatible "micromachining" processes that selectively etch away parts of the silicon wafer or add new structural layers to form the mechanical and electromechanical devices.MEMS promises to revolutionize nearly every product category by bringing together silicon-based microelectronics with micromachining technology, making possible the realization of complete systems-on-a-chip. MEMS is an enabling technology allowing the development of smart products, augmenting the computational ability of microelectronics with the perception and control capabilities of microsensors and microactuators and expanding the space of possible designs and applications.Microelectronic integrated circuits can be thought of as the "brains" of a system and MEMS augments this decision-making capability with "eyes" and "arms", to allow microsystems to sense and control the environment. Sensors gather information from the environment through measuring mechanical, thermal, biological, chemical, optical, and magnetic phenomena. The electronics then process the information derived from the sensors and through some decision making capability direct the actuators to respond by moving, positioning, regulating, pumping, and filtering, thereby controlling the environment for some desired outcome or purpose. Because MEMS devices are manufactured using batch fabrication techniques similar to those used for integrated circuits, unprecedented levels of functionality, reliability, and sophistication can be placed on a small silicon chip at a relatively low cost.
85MEMS compatible micro-GRIN lenses for fiber to chip coupling of light Michael Zickar, Wilfried Noell, Cornel Marxer, Nico de Rooij. Institute of Microtechnology (IMT), University of Neuchatel, Switzerland
87Novos materiais óptica integrada ® material for the fabrication of integrated optical and opto-electronic devices. They exhibit low optical losses in the NIR range, especially at the most important wavelengths for optical communications (0.3 dB/cm at 1320 nm, 0.6 dB/cm at 1550 nm, without fluorination). The refractive index is easily and reproducibly tunable by mixing with an appropriate resin of different index. Moreover, process parameters have been optimized to achieve low cost packaging even in higher layer thicknesses (at present 100 mm within one step). In addition to a mechanistic study of the initial polycondensation reaction, examples for the applicability of the mentioned materials are given. Embedded channel waveguides have been produced as well as active devices like digital optical switches.ORMOCER®s in general are a class of hybrid inorganic/organic materials which amongst other utilizations prove highly valuable for application in packaging of integrated circuits. They show good optical and dielectric properties as well as good thermal stability (decomposition not below 270 °C). Furthermore, their chemical synthesis meets the requirements of microoptics and microelectronics industry since it enables highly reproducible low cost production of ORMOCER® micro structures.ORMOCER®s are manufactured in a two-step process, the first of which consists of the hydrolysis and polycondensation reaction of organically functionalized alkoxysilanes. The following reaction scheme (1) depicts the modified synthesis of the presented materials which focuses on alkoxylation. Diphenylsilanediol is reacted with 3-methacryloxypropyltrimethoxysilane under addition of a suitable condensation catalyst:
88Outro sistemaFigure 6 (a) Manufacturing Optical Layers by Hot Embossing (Rib Cladding Process); (b) Manufacturing Optical Layers by Hot Embossing (Groove Filling Process) (Griese, 2002)
89Microfone ópticoFig. 1: optical principleFig. 2: basic build-upIn the last years several transduction mechanisms for optical microphone technology have been developed. These are based on phase, polarisation and intensity modulation of light. The developed fiber optical microphone (FOM) is based on an intensity modulation and transduces airborne acoustic signals to light wave signals. This project was funded by “Micro System Technology (MST) Niedersachsen” in cooperation with “Sennheiser”, “Gesamtzentrum für Verkehr” (GZVB) and “Laser Laboratorium Göttingen” (LLG).Optical principle:The main principle of the optical microphone is to detect the vibration of a membrane using light. The emitted light from an LED is sent through an optical fiber onto the membrane which is furnished with a reflecting spot. The reflected light is coupled into the receiving fiber. When sound waves agitate the membrane it starts to vibrate, resulting in a toggling of the light spot on the receiving fiber. Consequentially a different intensity can be detected at the photo diode and is transformed into an electrical signal.Basic build-up:The design of the optical microphone basically consists of a mechanical part - housing, chip holder and buckling protection - and a functional part - membrane and positioning chip. The positioning chip serves as a micro-macro-interface for fiber optics and contains discrete or integrated optical components with high precision self-adjustment. Structuring the optical fibers toproduce a prism by polishing the chipoptical work bench with discreteoptical componentsIntegrated optics like lenses, prismsand waveguides
90Temos elétrons em sólidos e fótons em......materiais fotônicos Cristais FotônicosElétrons de um lado e fótons do outro lado, junção de fóton + eletrônicoTemos elétrons em sólidos e fótons em......materiais fotônicos
91Cristais fotônicos Analogias Em Cristal Sólido Em Cristal Fotônico Analogia entre cristal sólido e cristal fotônico.AnalogiasportadoresestruturabandasdefeitosEm Cristal Sólidoelétronspotencial periódicobanda de energiadefeitos: estados dentro da banda proibidaEm Cristal Fotônicofótonsmodulação da constante dielétricaBanda de energia fotônica = photonic band gap (PBG)defeitos: estados dentro da banda com direcionalidade bem definidaEscola André Svieca 2002? Cid AraujoYablonovitch, PRL 58 (1987) 2059; John, PRL 58 (1987) 2486
92Band Theory: “Bound” Electron Approach For the total number N of atoms in a solid (1023 cm–3), N energy levels split apart within a width E.Leads to a band of energies for each initial atomic energy level (e.g. 1s energy band for 1s energy level).Two atomsSix atomsSolid of N atomsElectrons must occupy different energies due to Pauli Exclusion principle.
93Filtro de Fabry-Perot C_MEMS A C-MEMS Fabry-Perot filter consists of a micromachined silicon chip set comprising three or four individual chips. One chip has high-reflectivity and anti-reflective coatings on each side of its optically active area, which is surrounded by a large electrode. An elastomeric ring provides the filter's flexible element and provides a passive counterbalance to the electrostatic force. A second chip incorporates the drive electrodes, spaced several microns away from the movable mirror. Bonding the two pieces together with a reference mirror forms a basic mirror-driving unit with a reasonable voltage budget. An alternate configuration uses four chips to create two identical mirror-drive units.In either case, C-MEMS requires a low voltage budget to move the mirror along its normal optical axis and tune over the full range of channels in the C- or L-band at scan rates of at least 10 Hz. More important, it ensures a high degree of parallelism and a consistent filter shape with peak wavelength insertion losses under 2 dB.As a result of conditioning treatments, C-MEMS Fabry-Perot tunable filters have a simple calibration process. They only require a simple curve-fit method that yields accuracies of picometers. Such filters have demonstrated wavelength repeatability of 10 pm over the C-band tuning range.Like the optical networks they constitute, optical components confront diverse environmental conditions under which they must deliver consistent and predictable performance. The most common environmental factors are vibration and temperature change. Together, these factors present major design and packaging challenges for all devices placed in the optical path.Passive isolation-the common solution-proved insufficient to protect Fabry-Perot filters from residual environmental changes. A better approach is to configure filters with dual mirrors suspended in identical driving units. This enables common-mode cancellation principles to maintain zero relative differential movement for the mirror pairs-nulling environmental-vibration effects and yielding a stable filter peak position within several picometers when subjected to environmental vibration. This design has made C-MEMS tunable Fabry-Perot filters immune to the vibration encountered in normal operation.One effective design for C-MEMS Fabry-Perot filters maintains the core tunable filter chip set under a constant temperature condition. Heating the device to a higher temperature than the specified environmental extreme keeps the core filter chip set temperature stable.The supporting package temperature is still subject to environmental change and, if not properly isolated, mechanical thermal stress or stretch can impose wavelength drift. The solution: zero-stress or quasi-zero-stress attachment methods that minimize thermal stress spread into the optically active area. The approach enables reduction of peak wavelength temperature sensitivity to below 4 pm/ degrees C.If the device is configured to reoptimize every 30 minutes, it will lock the wavelength drift to less than plus/minus 30 pm under temperature-changing rates of 0.5 degrees C/minute. Performed more frequently, reoptimization can help reduce drift to less than 10 pm.
94O seguinte é um seminário dado por Steven G O seguinte é um seminário dado por Steven G. Johnson, MIT Applied Mathematics
95From electrons to photons: Quantum-inspired modeling in nanophotonics Steven G. Johnson, MIT Applied Mathematics
97can have a band gap: optical “insulators” Photonic Crystalsperiodic electromagnetic media18871987can have a band gap: optical “insulators”
98Electronic and Photonic Crystals atoms in diamond structuredielectric spheres, diamond latticewavevectorphoton frequencyPeriodicMediumBand DiagramBloch waves:electron energywavevectorinteracting: hard problemnon-interacting: easy problem
99Electronic & Photonic Modelling • strongly interacting—tricky approximations• non-interacting (or weakly),—simple approximations(finite resolution)—any desired accuracy• lengthscale dependent(from Planck’s h)• scale-invariant—e.g. size 10 10Option 1: Numerical “experiments” — discretize time & space … goOption 2: Map possible states & interactionsusing symmetries and conservation laws: band diagram
100Fun with Math get rid of this mess First task: dielectric function e(x) = n2(x)eigen-operatoreigen-valueeigen-state+ constraint
101Electronic & Photonic Eigenproblems nonlinear eigenproblem(V depends on e density ||2)simple linear eigenproblem(for linear materials)—many well-knowncomputational techniquesHermitian = real E & w, … Periodicity = Bloch’s theorem…
102A 2d Model System dielectric “atom” square lattice, a a TM e=12 (e.g. Si)square lattice,period aaaETMH
103Periodic Eigenproblems if eigen-operator is periodic, then Bloch-Floquet theorem applies:can choose:planewaveperiodic “envelope”Corollary 1: k is conserved, i.e. no scattering of Bloch waveCorollary 2: given by finite unit cell,so w are discrete wn(k)
104Solving the Maxwell Eigenproblem Finite cell discrete eigenvalues wnWant to solve for wn(k),& plot vs. “all” k for “all” n,constraint:where:H(x,y) ei(kx – wt)1Limit range of k: irreducible Brillouin zone2Limit degrees of freedom: expand H in finite basis3Efficiently solve eigenproblem: iterative methods
105Solving the Maxwell Eigenproblem: 1 Limit range of k: irreducible Brillouin zone1—Bloch’s theorem: solutions are periodic in kMkxkyfirst Brillouin zone= minimum |k| “primitive cell”XGirreducible Brillouin zone: reduced by symmetry2Limit degrees of freedom: expand H in finite basis3Efficiently solve eigenproblem: iterative methods
106Solving the Maxwell Eigenproblem: 2a Limit range of k: irreducible Brillouin zone12Limit degrees of freedom: expand H in finite basis (N)solve:finite matrix problem:3Efficiently solve eigenproblem: iterative methods
107Solving the Maxwell Eigenproblem: 2b Limit range of k: irreducible Brillouin zone12Limit degrees of freedom: expand H in finite basis— must satisfy constraint:Planewave (FFT) basisFinite-element basisconstraint, boundary conditions:Nédélec elements[ Nédélec, Numerische Math.35, 315 (1980) ]constraint:nonuniform mesh,more arbitrary boundaries,complex code & mesh, O(N)uniform “grid,” periodic boundaries,simple code, O(N log N)[ figure: Peyrilloux et al.,J. Lightwave Tech.21, 536 (2003) ]3Efficiently solve eigenproblem: iterative methods
108Solving the Maxwell Eigenproblem: 3a Limit range of k: irreducible Brillouin zone12Limit degrees of freedom: expand H in finite basis3Efficiently solve eigenproblem: iterative methodsSlow way: compute A & B, ask LAPACK for eigenvalues— requires O(N2) storage, O(N3) timeFaster way:— start with initial guess eigenvector h0— iteratively improve— O(Np) storage, ~ O(Np2) time for p eigenvectors(p smallest eigenvalues)
109Solving the Maxwell Eigenproblem: 3b Limit range of k: irreducible Brillouin zone12Limit degrees of freedom: expand H in finite basis3Efficiently solve eigenproblem: iterative methodsMany iterative methods:— Arnoldi, Lanczos, Davidson, Jacobi-Davidson, …,Rayleigh-quotient minimization
110Solving the Maxwell Eigenproblem: 3c Limit range of k: irreducible Brillouin zone12Limit degrees of freedom: expand H in finite basis3Efficiently solve eigenproblem: iterative methodsMany iterative methods:— Arnoldi, Lanczos, Davidson, Jacobi-Davidson, …,Rayleigh-quotient minimizationfor Hermitian matrices, smallest eigenvalue w0 minimizes:“variationaltheorem”minimize by preconditionedconjugate-gradient (or…)
111Band Diagram of 2d Model System (radius 0.2a rods, e=12) frequency w (2πc/a) = a / lirreducible Brillouin zoneGXMGMEgap forn > ~1.75:1TMXGH
112solutions are orthogonal and satisfy a variational theorem Origin of the Band GapHermitian eigenproblems:solutions are orthogonal and satisfy a variational theoremElectronicPhotonicfield oscillations• minimizekinetic + potential energy(e.g. “bonding” state)• minimize:field in high e• higher bands orthogonal to lower —must oscillate (high kinetic) or be in low e (high potential)(e.g. “anti-bonding” state)
113Origin of Gap in 2d Model System orthogonal: node in high eEzlives in high eGXMGEzEgap forn > ~1.75:1TMH–+
114The Iteration Scheme is Important (minimizing function of 104–108+ variables!)Steepest-descent: minimize (h + a f) over a … repeatConjugate-gradient: minimize (h + a d)— d is f + (stuff): conjugate to previous search dirsPreconditioned steepest descent: minimize (h + a d)— d = (approximate A-1) f ~ Newton’s methodPreconditioned conjugate-gradient: minimize (h + a d)— d is (approximate A-1) [f + (stuff)]
115The Iteration Scheme is Important (minimizing function of ~40,000 variables)no preconditioning% errorpreconditionedconjugate-gradientno conjugate-gradient# iterations
116The Boundary Conditions are Tricky E|| is continuousE is discontinuous(D = eE is continuous)Any single scalar e fails:(mean D) ≠ (any e) (mean E)Use a tensor e:E||Ee?
117The e-averaging is Important backwards averagingcorrect averagingchanges orderof convergencefrom ∆x to ∆x2% errorno averagingtensor averaging(similar effectsin other E&Mnumerics & analyses)resolution (pixels/period)
118But, what can we do with the gap? Gap, Schmap?afrequency wGXMGBut, what can we do with the gap?
119Intentional “defects” are good microcavitieswaveguides (“wires”)
120Intentional “defects” in 2d (Same computation, with supercell = many primitive cells)
121Microcavity Blues For cavities (point defects) frequency-domain has its drawbacks:• Best methods compute lowest-w bands,but Nd supercells have Nd modesbelow the cavity mode — expensive• Best methods are for Hermitian operators,but losses requires non-Hermitian
122Time-Domain Eigensolvers (finite-difference time-domain = FDTD) Simulate Maxwell’s equations on a discrete grid,+ absorbing boundaries (leakage loss)• Excite with broad-spectrum dipole ( ) sourceDwsignal processingResponse is manysharp peaks,one peak per modecomplex wn[ Mandelshtam,J. Chem. Phys. 107, 6756 (1997) ]decay rate in time gives loss
123Signal Processing is Tricky complex wn?a common approach: least-squares fit of spectrumfit to:FFTDecaying signal (t)Lorentzian peak (w)
124problem: have to run long enough to completely decay Fits and Uncertaintyproblem: have to run long enough to completely decayactualsignalportionPortion of decaying signal (t)Unresolved Lorentzian peak (w)There is a better way, which gets complex w to > 10 digits
125Unreliability of Fitting Process Resolving two overlapping peaks isnear-impossible 6-parameter nonlinear fit(too many local minima to converge reliably)sum of two peaksThere is a better way, which getscomplex wfor both peaksto > 10 digitsw = iw = iSum of two Lorentzian peaks (w)
126Given time series yn, write: Quantum-inspired signal processing (NMR spectroscopy): Filter-Diagonalization Method (FDM)[ Mandelshtam, J. Chem. Phys. 107, 6756 (1997) ]Given time series yn, write:…find complex amplitudes ak & frequencies wkby a simple linear-algebra problem!Idea: pretend y(t) is autocorrelation of a quantum system:say:time-∆t evolution-operator:
127Filter-Diagonalization Method (FDM) [ Mandelshtam, J. Chem. Phys. 107, 6756 (1997) ]We want to diagonalize U: eigenvalues of U are eiw∆t…expand U in basis of |(n∆t)>:Umn given by yn’s — just diagonalize known matrix!
128Filter-Diagonalization Summary [ Mandelshtam, J. Chem. Phys. 107, 6756 (1997) ]Umn given by yn’s — just diagonalize known matrix!A few omitted steps:—Generalized eigenvalue problem (basis not orthogonal) —Filter yn’s (Fourier transform):small bandwidth = smaller matrix (less singular)• resolves many peaks at once• # peaks not known a priori• resolve overlapping peaks• resolution >> Fourier uncertainty
129Do try this at homeBloch-mode eigensolver:Filter-diagonalization:Photonic-crystal tutorials (+ THIS TALK):/photons/tutorial/