An Integrated-Photonics Optical-Frequency Synthesizer

Integrated-photonics microchips now enable a range of advanced functionalities for high-coherence applications such as data transmission, highly optimized physical sensors, and harnessing quantum states, but with cost, efficiency, and portability much beyond tabletop experiments. Through high-volume semiconductor processing built around advanced materials there exists an opportunity for integrated devices to impact applications cutting across disciplines of basic science and technology. Here we show how to synthesize the absolute frequency of a lightwave signal, using integrated photonics to implement lasers, system interconnects, and nonlinear frequency comb generation. The laser frequency output of our synthesizer is programmed by a microwave clock across 4 THz near 1550 nm with 1 Hz resolution and traceability to the SI second. This is accomplished with a heterogeneously integrated III/V-Si tunable laser, which is guided by dual dissipative-Kerr-soliton frequency combs fabricated on silicon chips. Through out-of-loop measurements of the phase-coherent, microwave-to-optical link, we verify that the fractional-frequency instability of the integrated photonics synthesizer matches the $7.0*10^{-13}$ reference-clock instability for a 1 second acquisition, and constrain any synthesis error to $7.7*10^{-15}$ while stepping the synthesizer across the telecommunication C band. Any application of an optical frequency source would be enabled by the precision optical synthesis presented here. Building on the ubiquitous capability in the microwave domain, our results demonstrate a first path to synthesis with integrated photonics, leveraging low-cost, low-power, and compact features that will be critical for its widespread use.Comment: 10 pages, 6 figure

Programmable Logic Devices in Experimental Quantum Optics

We discuss the unique capabilities of programmable logic devices (PLD's) for experimental quantum optics and describe basic procedures of design and implementation. Examples of advanced applications include optical metrology and feedback control of quantum dynamical systems. As a tutorial illustration of the PLD implementation process, a field programmable gate array (FPGA) controller is used to stabilize the output of a Fabry-Perot cavity

Precision Clock for Moon Bouncing

As comunicações Earth-Moon-Earth, também conhecidas como moon bouncing, consistem em transmitir um sinal para a Lua e receber seu eco. Embora já não sejam usadas para comunicações, ainda representam um desafio interessante a ser superado devido à grande distância que separa os dois corpos. Uma prática semelhante é a de fazer radar na superfície da Lua. Para fazer isso, uma alta coerência de fase entre o sinal transmitido e o sinal recebido é necessária para correlacionar ambos e formar uma imagem. Isso é feito usando uma referência de relógio muito estável. O objetivo desta tese é criar uma referência de tempo estável e precisa, utilizável para moon bouncing, sendo ao mesmo tempo de menor custo em comparação com as alternativas do mercado. Um GPS Disciplined Oscillator (GPSDO) será desenvolvido para atingir esse objetivo. Consiste num Oscilador local (neste caso um OCXO) escravizado ao Pulso Por Segundo (PPS) de um GPS aproveitando assim a estabilidade de curto prazo do primeiro e a estabilidade de longo prazo do último. O seu princípio de funcionamento é muito semelhante ao de uma Phase Locked Loop (PLL) diferindo principalmente no filtro do loop onde o GPSDO usa um microcontrolador para executar um algoritmo que ajusta o oscilador local com base nas leituras de suas entradas. Primeiramente, um diagrama de blocos baseado numa PLL comum será estabelecido e posteriormente melhorado para atender à resolução e aplicações exigidas. Os componentes serão selecionados tendo em consideração as rígidas restrições de tempo e o sistema será montado. Um algoritmo PID será então desenvolvido para controlar o loop. Finalmente, o sistema será testado e comparado com o resultado esperado e outras referências de tempo. O objetivo do autor nesta tese é alcançar uma estabilidade de frequência de curto prazo de 0,0218 PPB, que corresponde à variação de um quarto do período da portadora ( de frequência 2,45GHz) durante o tempo que o sinal leva para ir nos dois sentidos entre a Terra e a lua.Earth-Moon-Earth communications, also known as moon bouncing, consist on transmitting a signal to the Moon and receiving its echo. Although not used for communications anymore, it still poses an interesting challenge to overcome due to the large distance that separates both bodies. Similarly to that practice is the one of doing radar on the moon's surface. To do so, an high phase coherence between the transmitted and the received signal is needed in order to correlate both to make an image. This is accomplished by using a very stable clock reference. The goal of this thesis is to create a stable and precise time reference, usable for moon bouncing, while being of lower cost compared to alternatives in the market. A GPS Disciplined Oscillator (GPSDO) will be developed to achieve that goal. It consists on a local Oscillator (in this case an OCXO) enslaved to the Pulse Per Second (PPS) signal of a GPS thus taking advantage of both the short term stability of the first and the long term stability of the latter. Its working principle is very similar to that of a Phase Locked Loop (PLL) differing mainly on the loop filter where the GPSDO uses a microcontroller to run an algorithm that adjusts the local oscillator based on readings from its inputs. Firstly, a block diagram based on a common PLL will be established and later improved to meet the required resolution and applications. The components will be selected taking into account the strict time restrictions and the system will be assembled. A PID algorithm will then be developed to control the loop. Finally, the system will be tested and compared with the expected result and other time references. The author's objective in this thesis is to achieve a short-term frequency stability of 0.0218 PPB, which corresponds to the variation of a quarter of the carrier period (of frequency 2,45GHz) during the time it takes for the signal to go both ways between the Earth and the moon

Towards attosecond 4D imaging of atomic-scale dynamics by single-electron diffraction

Many physical and chemical processes which define our daily life take place on atomic scales in space and time. Time-resolved electron diffraction is an excellent tool for investigation of atomic-scale structural dynamics (4D imaging) due to the short de Broglie wavelength of fast electrons. This requires electron pulses with durations on the order of femtoseconds or below. Challenges arise from Coulomb repulsion and dispersion of non-relativistic electron wave packets in vacuum, which currently limits the temporal resolution of diffraction experiments to some hundreds of femtoseconds. In order to eventually advance the temporal resolution of electron diffraction into the few-femtosecond range or below, four new concepts are investigated and combined in this work: First, Coulomb repulsion is avoided by using only a single electron per pulse, which does not repel itself but interferes with itself when being diffracted from atoms. Secondly, dispersion control for electron pulses is implemented with time-dependent electric fields at microwave frequencies, compressing the duration of single-electron pulses at the expense of simultaneous energy broadening. Thirdly, a microwave signal used for electron pulse compression is derived from an ultrashort laser pulse train. Optical enhancement allows a temporal synchronization between the microwave field and the laser pulses with a precision below one femtosecond. Fourthly, a cross-correlation between laser and electron pulses is measured in this work with the purpose of determining the possible temporal resolution of diffraction experiments employing compressed single-electron pulses. This novel characterization method uses the principles of a streak camera with optical fields and potentially offers attosecond temporal resolution. These four concepts show a clear path towards improving the temporal resolution of electron diffraction into the few-femtosecond domain or below, which opens the possibility of observing electron densities in motion. In this work, a compressed electron pulse's duration of 28±5 fs full width at half maximum (12±2 fs standard deviation) at a de Broglie wavelength of 0.08 Å is achieved. Currently, this constitutes the shortest electron pulses suitable for diffraction, about sixfold shorter than in previous work. Ultrafast electron diffraction now meets the requirements for investigating the fastest primary processes in molecules and solids with atomic resolution in space and time

Power Management ICs for Internet of Things, Energy Harvesting and Biomedical Devices

This dissertation focuses on the power management unit (PMU) and integrated circuits (ICs) for the internet of things (IoT), energy harvesting and biomedical devices. Three monolithic power harvesting methods are studied for different challenges of smart nodes of IoT networks. Firstly, we propose that an impedance tuning approach is implemented with a capacitor value modulation to eliminate the quiescent power consumption. Secondly, we develop a hill-climbing MPPT mechanism that reuses and processes the information of the hysteresis controller in the time-domain and is free of power hungry analog circuits. Furthermore, the typical power-performance tradeoff of the hysteresis controller is solved by a self-triggered one-shot mechanism. Thus, the output regulation achieves high-performance and yet low-power operations as low as 12 µW. Thirdly, we introduce a reconfigurable charge pump to provide the hybrid conversion ratios (CRs) as 1⅓× up to 8× for minimizing the charge redistribution loss. The reconfigurable feature also dynamically tunes to maximum power point tracking (MPPT) with the frequency modulation, resulting in a two-dimensional MPPT. Therefore, the voltage conversion efficiency (VCE) and the power conversion efficiency (PCE) are enhanced and flattened across a wide harvesting range as 0.45 to 3 V. In a conclusion, we successfully develop an energy harvesting method for the IoT smart nodes with lower cost, smaller size, higher conversion efficiency, and better applicability. For the biomedical devices, this dissertation presents a novel cost-effective automatic resonance tracking method with maximum power transfer (MPT) for piezoelectric transducers (PT). The proposed tracking method is based on a band-pass filter (BPF) oscillator, exploiting the PT’s intrinsic resonance point through a sensing bridge. It guarantees automatic resonance tracking and maximum electrical power converted into mechanical motion regardless of process variations and environmental interferences. Thus, the proposed BPF oscillator-based scheme was designed for an ultrasonic vessel sealing and dissecting (UVSD) system. The sealing and dissecting functions were verified experimentally in chicken tissue and glycerin. Furthermore, a combined sensing scheme circuit allows multiple surgical tissue debulking, vessel sealer and dissector (VSD) technologies to operate from the same sensing scheme board. Its advantage is that a single driver controller could be used for both systems simplifying the complexity and design cost. In a conclusion, we successfully develop an ultrasonic scalpel to replace the other electrosurgical counterparts and the conventional scalpels with lower cost and better functionality

High resolution rotation sensor based on cold atom interferometry

[no abstract

Phase Noise Analyses and Measurements in the Hybrid Memristor-CMOS Phase-Locked Loop Design and Devices Beyond Bulk CMOS

Phase-locked loop (PLLs) has been widely used in analog or mixed-signal integrated circuits. Since there is an increasing market for low noise and high speed devices, PLLs are being employed in communications. In this dissertation, we investigated phase noise, tuning range, jitter, and power performances in different architectures of PLL designs. More energy efficient devices such as memristor, graphene, transition metal di-chalcogenide (TMDC) materials and their respective transistors are introduced in the design phase-locked loop. Subsequently, we modeled phase noise of a CMOS phase-locked loop from the superposition of noises from its building blocks which comprises of a voltage-controlled oscillator, loop filter, frequency divider, phase-frequency detector, and the auxiliary input reference clock. Similarly, a linear time-invariant model that has additive noise sources in frequency domain is used to analyze the phase noise. The modeled phase noise results are further compared with the corresponding phase-locked loop designs in different n-well CMOS processes. With the scaling of CMOS technology and the increase of the electrical field, the problem of short channel effects (SCE) has become dominant, which causes decay in subthreshold slope (SS) and positive and negative shifts in the threshold voltages of nMOS and pMOS transistors, respectively. Various devices are proposed to continue extending Moore\u27s law and the roadmap in semiconductor industry. We employed tunnel field effect transistor owing to its better performance in terms of SS, leakage current, power consumption etc. Applying an appropriate bias voltage to the gate-source region of TFET causes the valence band to align with the conduction band and injecting the charge carriers. Similarly, under reverse bias, the two bands are misaligned and there is no injection of carriers. We implemented graphene TFET and MoS2 in PLL design and the results show improvements in phase noise, jitter, tuning range, and frequency of operation. In addition, the power consumption is greatly reduced due to the low supply voltage of tunnel field effect transistor