High quality entangled photon sources are a key requirement for many promising quantum optical technologies. However, the production of multi-photon entangled states with good fidelity is challenging. Current sources of multi-photon entanglement require the use of post-selection, which limits their usefulness for some applications. It has been an open challenge to create a source capable of directly producing three-photon entanglement. An important step in this direction was achieved with the demonstration of photon triplets produced by a new process called cascaded downconversion, but these previous measurements were not sufficient to show whether these photons were in an entangled state and only had detection rates of five triplets per hour. In this thesis, we show the first demonstration of a direct source of three-photon entanglement. Our source is based on cascaded downconversion, and we verify that it produces genuine tripartite entanglement in two degrees of freedom: energy-time and polarization. The energy-time entanglement is similar to a three-particle generalization of an Einstein-Podolski-Rosen state; the three photons are created simultaneously, yet the sum of their energies is well defined, which is an indication of energy-time entanglement. To prove it, we use time-bandwidth inequalities which check for genuine tripartite entanglement. Our measurements show that the state violates the inequalities with what constitute, to the best of our knowledge, the strongest violation of time-bandwidth inequalities in a tripartite continuous-variable system to date. We create polarization entanglement by modifying our experimental setup so that two downconversion processes producing orthogonally polarized triplets interfere to create Greenberger-Horne-Zeilinger states. By using highly efficient superconducting nanowire single photon detectors, we improve the detected triplet rate by 2 orders of magnitude to 660 triplets per hour. We characterize the state using quantum state tomography, and find a fidelity of 86\% with the ideal state, beating the previous best value for a three-photon entangled state fidelity measured by tomography. We also use the state to perform two tests of local realism. We violate the Mermin and Svetlichny inequalities by 10 and 5 standard deviations respectively, the latter being the strongest violation to date. Finally, we show that, unlike previous sources of tree-photon entanglement, our source can be used as a source of heralded Bell pairs. We demonstrate this by measuring a CHSH inequality with the heralded Bell pairs, and by reconstructing their state using quantum state tomography.

<p> In past years, wireless technology has seen an incredible boom. As a result, industry has gone to great lengths to make wireless devices cheaper, smaller, faster and less power- hungry. This has prompted a significant interest in the research world to design circuit components that would facilititate these goals. However, much of the focus has been on wireless technology for communications applications, such as wireless telephony and wireless computer networking. More recently, there has been a focus on developing circuits for other wireless applications, one of which is wireless sensor networks. Such applications would demand extremely low-power operation, especially from the RF front-end. We have concentrated on achieving low-power operation for one of the important building blocks of the RF transceiver, which is the frequency downconversion mixer. </p> <p> In this thesis, we describe the design and results of two mixers, both designed in CMOS O.l8J.Lm technology offered by the Canadian Microelectronics Corporation (CMC). The first design uses the body terminal of the transistor as one of the inputs. This method allows for the radio-frequency (RF) and local oscillator (LO) stages in traditional switching mixers to be collapsed into one stage, thereby allowing for operation at lower supply voltages and lower power comsumption levels. This mixer was designed to downconvert a 1.9GHz RF signal to a 250MHz intermediate-frequency (IF) signal. The measured performance characteristics resulted in a power consumption of 400J.LW from a 0.8V supply, a conversion gain of 1dB, a single sideband (SSB) noise figure of 1ldB, and an input-referred 3rd-order intercept point (IIP3) of -9dBm. </p> <p> The second mixer design used a folding architecture to reduce the supply voltage headroom needed, as well as distribute the current appropriately for high-gain and lowpower operation. This mixer was designed to downconvert a 2.4GHz RF signal to a 100MHz IF signal. The simulated performance characteristics showed a power consumption of 640).1 W from a 1 V supply, a conversion gain of 4dB, a SSB noise figure of 19dB, and an IIP3 of -6.5dBm. </p> / Thesis / Master of Applied Science (MASc)

Abstract Subsampling can be used in a radio receiver to perform signal downconversion and sample-and-hold operations in order to relieve the operation frequency and bandwidth requirements of the subsequent discrete-time circuitry. However, due to the inherent aliasing behaviour of wideband noise and interference in subsampling, and the difficulty of implementing appropriate bandpass anti-aliasing filtering at high frequencies, straightforward use of a low subsampling rate can result in significant degradation of the receiver dynamic range. The aim of this thesis is to investigate and implement methods for integrating filtering into high-frequency signal sampling and downconversion by subsampling to alleviate the requirements for additional front-end filters and to mitigate the effects of noise and out-of-band signal aliasing, thereby facilitating use in integrated high-quality radio receivers. The charge-domain sampling technique studied here allows simple integration of both continuous-and discrete-time filtering functions into high-frequency signal sampling. Gated current integration results in a lowpass sin(x)/x(sinc(x)) response capable of performing built-in anti-aliasing filtering in baseband signal sampling. Weighted integration of several successive current samples can be further used to obtain an embedded discrete-time finite-impulse-response (FIR) filtering response, which can be used for internal anti-aliasing and image-rejection filtering in the downconversion of bandpass signals by subsampling. The detailed analysis of elementary charge-domain sampling circuits presented here shows that the use of integrated FIR filtering with subsampling allows acceptable noise figures to be achieved and can provide effective internal anti-aliasing rejection. The new methods for increasing the selectivity of elementary charge-domain sampling circuits presented here enable the integration of advanced, digitally programmable FIR filtering functions into high-frequency signal sampling, thereby markedly relieving the requirements for additional anti-aliasing, image rejection and possibly even channel selection filters in a radio receiver. BiCMOS and CMOS IF sampler implementations are presented in order to demonstrate the feasibility of the charge-domain sampling technique for integrated anti-aliasing and image-rejection filtering in IF signal quadrature downconversion by subsampling. Circuit measurements show that this sampling technique for built-in filtering results in an accurate frequency response and allows the use of high subsampling ratios while still achieving a competitive dynamic range.

This thesis presents detail theoretical analysis of downconversion Gilbert cell mixer with the improvements on major performance parameters by utilizing different substrate biasing techniques. By modifying the threshold voltage of the switching core, the LO transistors perform more ideally as a perfect switch. It improves the active mixer performances in conversion gain, noise and linearity performances. The techniques are implemented on a 1.2 V low power CMOS downconversion mixer for performance comparisons between simulation and measurements result. They are realized in TSMC 0.18 um CMOS technology. It shows that body-biasing techniques help to increase the switching efficiency of the Gilbert mixer. And a mixer with a better switching provides better performance. With no additional power consumption, the no body effect technique in Design B has shown a 1.5 dB higher in conversion gain, 2 dBm higher in IIP3, and a 0.5 dB lower in NF performance. With the varying biasing technique implemented in Design C, it shows an improvement of 22 dB in conversion gain. Both Design B and C have less than 2 mW power consumption and are suitable for Bluetooth applications. This thesis introduces a stage-by-stage procedure for designing a Gilbert mixer; design tradeoffs at each stage are also discussed. / Thesis / Master of Applied Science (MASc)

ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, California / A Synthetic Beamforming antenna was built for Airborne Telemetry. Low-Noise Block-converters translated RF to IF suitable for direct analog-to-digital conversion. Then all telemetry functions were performed digitally via parallel FPGAs for 10 independent sources. Monopulse tracking and optimal diversity combination was performed using 4 antenna quadrants at two orthogonal polarizations. Novel estimation approaches drove digital demodulation, symbol- and bit- synchronization. Final telemetry outputs include: digital, analog (video), and analog IF (e.g., for downlink relay). This program has incubated several concepts that we believe have the combined potential to significantly improve the future of telemetry.

Neste trabalho foram estudados diferentes vidros de telureto dopados com íons de terras raras (TR) e nanopartículas (NPs) metálicas visando aplicação sobre a superfície de dispositivos fotovoltaicos. O objetivo foi utilizar os processos luminescentes de tais íons para otimizar a eficiência de conversão de energia de células solares. Os vidros de telureto foram escolhidos por apresentarem boas características ópticas, físicas e luminescência na presença de íons de terra rara e de NPs. Diferentes composições de telureto foram estudadas (TeO2-ZnO, TeO2-ZnO-Na2CO3) para observar a influência de diferentes janelas de transmissão sobre o desempenho de células solares, conciliando a máxima luminescência com a máxima transmitância do vidro. As amostras vítreas foram produzidas mediante o processo tradicional conhecido por \"melting quenching\" seguido por tratamento térmico. Os dopantes utilizados foram os íons de Tb3+, Yb3+, Eu3+ e nanopartículas de prata (NPs de Ag). Através dos mecanismos de conversão descendente apresentados por tais íons é possível converter comprimentos de onda que o dispositivo fotovoltaico não absorveria, para comprimentos compreendidos no seu \"band gap\" de forma a aumentar a eficiência da célula solar. Foram feitas caracterizações espectroscópicas de luminescência, absorbância e transmitância para caracterizar as propriedades ópticas dos vidros e microscopias para observar a forma e tamanho das NPs. Também foram feitas caracterizações elétricas de dispositivos fotovoltaicos com as amostras vítreas colocadas sobre suas superfícies, a fim de verificar influencias em suas eficiências. Observou-se que o tipo de célula solar e o tipo de sistema vítreo influenciam os resultados de eficiência para cada combinação de íons de terras raras. Ressaltam-se que foram obtidos aumentos na eficiência relativa de dispositivos fotovoltaicos comerciais fabricados em Si e GaP em 14% e 34,5%, respectivamente, com a utilização de vidros TeO2-ZnO dopados com Eu3+ e NPs de Ag. Foi utilizado óleo para acoplamento entre o vidro e a célula solar para aumentar o contato óptico, que possibilitou fazer a comparação da eficiência da célula coberta em relação à célula descoberta. Usando a célula solar de Si monocristalino foi observado aumento de 12,8% de eficiência relativa, quando coberta com vidros TeO2-ZnO dopados com Eu3+ e NPs de Ag. Os resultados apresentados neste trabalho demonstram que a utilização de processos de conversão descendente de íons de TR em vidros de telureto são promissores para incrementar a eficiência de células solares, assim como, o uso de NPs metálicas. / In this work, different tellurite glasses doped with rare earth ions and metallic nanoparticles (NPs) were studied for applications on solar cells surface. The goal was to use the luminescent processes of the rare earth ions to optimize the solar cells energy conversion efficiency. Tellurite glasses were chosen because of the good optical and physical characteristics and luminescence in the presence of rare earth ions and metallic NPs. Different tellurite compositions were studied (TeO2-ZnO, TeO2-ZnO-Na2CO3) to observe the influence of different transmission windows on the solar cell performance, conciliating maximum luminescence with the maximum transmittance of the glasses. The vitreous samples were produced using the traditional \"melting quenching\" procedure followed by heat treatment. The dopants used were Tb3+, Yb3+, Eu3+ ions and silver NPs. The purpose was to use the downconversion processes of rare earth ions to convert the wavelengths that the photovoltaic device cannot absorb into wavelengths situated in its the band gap and enhance the energy conversion efficiency. Luminescence, absorption and transmittance spectroscopic characterizations were made to determine the optical properties of the glasses and microscopic measurements were used to observe the NPs size and shape. Electrical characterizations of the photovoltaic devices were also done with the glasses placed on their surfaces to verify the influence on their energy conversion efficiencies. It was observed that the type of solar cell and the glass host influenced the results, for each rare-earth ions combination. The results obtained with TeO2-ZnO glasses doped with Eu3+ and silver NPs can be highlighted, which show efficiency increase in 14% and 34,5%, when covering Si and GaP commercial solar cells, respectively. The oil matching was used between the solar cell and the glasses in order to enhance the optical contact and to allow the comparison between the results of the covered solar cell with the uncovered solar cell. It was observed for the energy conversion efficiency enhancement of 12% when the Si solar cell was covered with the TeO2-ZnO glasses doped with Eu3+ and with silver NPs. The results presented in this work demonstrate that the use of the rare earth ions downconversion processes are promising for improving the solar cells energy conversion efficiency as well as the use of metallic NPs.

Neste trabalho foram estudados diferentes vidros de telureto dopados com íons de terras raras (TR) e nanopartículas (NPs) metálicas visando aplicação sobre a superfície de dispositivos fotovoltaicos. O objetivo foi utilizar os processos luminescentes de tais íons para otimizar a eficiência de conversão de energia de células solares. Os vidros de telureto foram escolhidos por apresentarem boas características ópticas, físicas e luminescência na presença de íons de terra rara e de NPs. Diferentes composições de telureto foram estudadas (TeO2-ZnO, TeO2-ZnO-Na2CO3) para observar a influência de diferentes janelas de transmissão sobre o desempenho de células solares, conciliando a máxima luminescência com a máxima transmitância do vidro. As amostras vítreas foram produzidas mediante o processo tradicional conhecido por \"melting quenching\" seguido por tratamento térmico. Os dopantes utilizados foram os íons de Tb3+, Yb3+, Eu3+ e nanopartículas de prata (NPs de Ag). Através dos mecanismos de conversão descendente apresentados por tais íons é possível converter comprimentos de onda que o dispositivo fotovoltaico não absorveria, para comprimentos compreendidos no seu \"band gap\" de forma a aumentar a eficiência da célula solar. Foram feitas caracterizações espectroscópicas de luminescência, absorbância e transmitância para caracterizar as propriedades ópticas dos vidros e microscopias para observar a forma e tamanho das NPs. Também foram feitas caracterizações elétricas de dispositivos fotovoltaicos com as amostras vítreas colocadas sobre suas superfícies, a fim de verificar influencias em suas eficiências. Observou-se que o tipo de célula solar e o tipo de sistema vítreo influenciam os resultados de eficiência para cada combinação de íons de terras raras. Ressaltam-se que foram obtidos aumentos na eficiência relativa de dispositivos fotovoltaicos comerciais fabricados em Si e GaP em 14% e 34,5%, respectivamente, com a utilização de vidros TeO2-ZnO dopados com Eu3+ e NPs de Ag. Foi utilizado óleo para acoplamento entre o vidro e a célula solar para aumentar o contato óptico, que possibilitou fazer a comparação da eficiência da célula coberta em relação à célula descoberta. Usando a célula solar de Si monocristalino foi observado aumento de 12,8% de eficiência relativa, quando coberta com vidros TeO2-ZnO dopados com Eu3+ e NPs de Ag. Os resultados apresentados neste trabalho demonstram que a utilização de processos de conversão descendente de íons de TR em vidros de telureto são promissores para incrementar a eficiência de células solares, assim como, o uso de NPs metálicas. / In this work, different tellurite glasses doped with rare earth ions and metallic nanoparticles (NPs) were studied for applications on solar cells surface. The goal was to use the luminescent processes of the rare earth ions to optimize the solar cells energy conversion efficiency. Tellurite glasses were chosen because of the good optical and physical characteristics and luminescence in the presence of rare earth ions and metallic NPs. Different tellurite compositions were studied (TeO2-ZnO, TeO2-ZnO-Na2CO3) to observe the influence of different transmission windows on the solar cell performance, conciliating maximum luminescence with the maximum transmittance of the glasses. The vitreous samples were produced using the traditional \"melting quenching\" procedure followed by heat treatment. The dopants used were Tb3+, Yb3+, Eu3+ ions and silver NPs. The purpose was to use the downconversion processes of rare earth ions to convert the wavelengths that the photovoltaic device cannot absorb into wavelengths situated in its the band gap and enhance the energy conversion efficiency. Luminescence, absorption and transmittance spectroscopic characterizations were made to determine the optical properties of the glasses and microscopic measurements were used to observe the NPs size and shape. Electrical characterizations of the photovoltaic devices were also done with the glasses placed on their surfaces to verify the influence on their energy conversion efficiencies. It was observed that the type of solar cell and the glass host influenced the results, for each rare-earth ions combination. The results obtained with TeO2-ZnO glasses doped with Eu3+ and silver NPs can be highlighted, which show efficiency increase in 14% and 34,5%, when covering Si and GaP commercial solar cells, respectively. The oil matching was used between the solar cell and the glasses in order to enhance the optical contact and to allow the comparison between the results of the covered solar cell with the uncovered solar cell. It was observed for the energy conversion efficiency enhancement of 12% when the Si solar cell was covered with the TeO2-ZnO glasses doped with Eu3+ and with silver NPs. The results presented in this work demonstrate that the use of the rare earth ions downconversion processes are promising for improving the solar cells energy conversion efficiency as well as the use of metallic NPs.

This thesis presents a Hamiltonian formulation of the electromagnetic fields in structured (inhomogeneous) media of arbitrary dimensionality, with arbitrary material dispersion and absorption consistent with causality. The method is based on an identification of the photonic component of the polariton modes of the system. Although the medium degrees of freedom are introduced in an oscillator model, only the macroscopic response of the medium appears in the derived eigenvalue equation for the polaritons. For both the discrete transparent-regime spectrum and the continuous absorptive-regime spectrum, standard codes for photonic modes in nonabsorptive systems can easily be leveraged to calculate polariton modes. Two applications of the theory are presented: pulse propagation and spontaneous parametric down-conversion (SPDC). In the propagation study, the dynamics of the nonfluctuating part of a classical-like pulse are expressed in terms of a Schr\"{o}dinger equation for a polariton effective field. The complex propagation parameters of that equation can be obtained from the same generalized dispersion surfaces typically used while neglecting absorption, without incurring additional computational complexity. As an example I characterize optical pulse propagation in an Au/MgF$_2$ metallodielectric stack, using the empirical response function, and elucidate the various roles of Bragg scattering, interband absorption and field expulsion. Further, I derive the Beer coefficient in causal structured media. The SPDC calculation is rigorous, captures the full 3D physics, and properly incorporates linear dispersion. I obtain an expression for the down-converted state, quantify pair-production properties, and characterize the scaling behavior of the SPDC energy. Dispersion affects the normalization of the polariton modes, and calculations of the down-conversion efficiency that neglect this can be off by 100$\%$ or more for common media regardless of geometry if the pump is near the band edge. Furthermore, I derive a 3D three-wave group velocity walkoff factor; due to the interplay of a topological property with a symmetry property, I show that even if down-conversion is into a narrow forward cone, neglect of the transverse walkoff can lead to an overestimate of the SPDC energy by orders of magnitude.

This thesis presents a Hamiltonian formulation of the electromagnetic fields in structured (inhomogeneous) media of arbitrary dimensionality, with arbitrary material dispersion and absorption consistent with causality. The method is based on an identification of the photonic component of the polariton modes of the system. Although the medium degrees of freedom are introduced in an oscillator model, only the macroscopic response of the medium appears in the derived eigenvalue equation for the polaritons. For both the discrete transparent-regime spectrum and the continuous absorptive-regime spectrum, standard codes for photonic modes in nonabsorptive systems can easily be leveraged to calculate polariton modes. Two applications of the theory are presented: pulse propagation and spontaneous parametric down-conversion (SPDC). In the propagation study, the dynamics of the nonfluctuating part of a classical-like pulse are expressed in terms of a Schr\"{o}dinger equation for a polariton effective field. The complex propagation parameters of that equation can be obtained from the same generalized dispersion surfaces typically used while neglecting absorption, without incurring additional computational complexity. As an example I characterize optical pulse propagation in an Au/MgF$_2$ metallodielectric stack, using the empirical response function, and elucidate the various roles of Bragg scattering, interband absorption and field expulsion. Further, I derive the Beer coefficient in causal structured media. The SPDC calculation is rigorous, captures the full 3D physics, and properly incorporates linear dispersion. I obtain an expression for the down-converted state, quantify pair-production properties, and characterize the scaling behavior of the SPDC energy. Dispersion affects the normalization of the polariton modes, and calculations of the down-conversion efficiency that neglect this can be off by 100$\%$ or more for common media regardless of geometry if the pump is near the band edge. Furthermore, I derive a 3D three-wave group velocity walkoff factor; due to the interplay of a topological property with a symmetry property, I show that even if down-conversion is into a narrow forward cone, neglect of the transverse walkoff can lead to an overestimate of the SPDC energy by orders of magnitude.

This thesis covers three different topics. The first part is a pedagogical review of the basic principles and recent advances in nonlinear optics. It was originally written as a chapter for the proceedings of the “International School of Physics (Enrico Fermi)” summer school on Photonics held in June, 2014. It is included to provide some background information about nonlinear optical processes in general, and is particularly relevant for the third part of this thesis which is based on the second-order nonlinear optical process of spontaneous parametric downconversion. The second part is based on original research, and deals with superradiance in plasmonic nanostructures. The process of superradiance, as introduced by Dicke in 1954, entails the shortening of the spontaneous emission lifetime of a collection of N quantum emitters as a consequence of the development of a macroscopic dipole moment. Specifically, the lifetime is shortened by a factor of 1/N, and the linewidth is broadened by a factor of N. Such a linewidth dependence has been previously observed in systems of several plasmonic ‘emitters’. However, a clear physical insight into this phenomenon and how it relates to Dicke superradiance has not been shown yet. In this part, we demonstrate by experiment, simulation, and a simple analytical model that Dicke’s superradiance can indeed be observed in a planar array of plasmonic nanoantennas, with a linewidth that scales linearly with the number of nanoantennas within a square wavelength. The third part is also based on original research, and is based on the scal- ing laws of spontaneous parametric downconversion (SPDC) for a type-I phase- matching configuration. The variation of bi-photon generation rate, heralding efficiency and radiance with parameters such as crystal length, pump focussing and collection waist sizes are examined for collinear and non-collinear emission. The results can be used to maximize the brightness of the SPDC source or increase the heralding efficiency depending on the application.