誘導性エネルギー蓄積に基づくパルスパワー発生に関する研究

国立大学法人長岡技術科学大

Low-Power and Compact CMOS APS Circuits for Hybrid Cryogenic Infrared Fast Imaging

Peer reviewe

Active optical devices in silicon-on-insulator rib waveguides.

Much progress has been made in the development of active silicon opto-electronic devices over the last 15 years. This is primarily due to the widely accepted belief that the free carrier effect is the most efficient optical modulation and switching mechanism in silicon, along with the potential advantages of combining optical and electronic devices onto a single silicon substrate rather than using discrete components. A study of the scientific literature shows that whilst numerous devices have been reported, few have been seriously optimised. In the literature, devices have consisted primarily of two or three terminal devices based around a rib waveguide. The three terminal devices are fewer in number but generally perform better. Conversely, two terminal devices have received a little more attention in terms of producing faster devices. Therefore, this work provides an in depth analysis of the performance of p+-i-n+ diodes when configured as optical modulators, with the aim of improving both the device DC and transient performance characteristics. The primary DC performance characteristic is the current required to achieve a given phase change and the transient performance characteristics are measured in terms of the device rise and fall times. These characteristics have been studied with variations in geometrical and fabrication based parameters such as the position and doping concentration of the contacts, the aspect ratio of the rib waveguides, and the overall dimensions. The key result from the modelling is that the most efficient multi-micron size device is a three terminal device with high doping concentration, constant doping profiles and large diffusion depth doped regions located close to the rib edge. A theoretical device of this nature required a current of only 2.7mA for a ? radian phase shift with rise and fall times of 22ns and 2ns respectively. The best previously achieved was a device which theoretically required 4mA for a ? radian phase shift. Additionally, by including isolation trenches on either side of the doped regions the DC performance characteristics can be further improved by up to 74%. There are also advantages in reducing the dimensions of the devices to 1 micron or less. At these dimensions the DC and transient performance characteristics are improved by more than a further order of magnitude, hence requiring fractions of 1mA for a ? radian phase shift. Two of the most promising designs have been fabricated and experimentally analysed. Due to fabrication constraints the most efficient device was not fabricated. However, both two and three terminal devices were fabricated. The best device tested experimentally was a three terminal device that required a current of 14mA for a ? phase shift. The modelling and experimental results agree well therefore validating the modelling. Therefore we can be confident that the additional theoretical results for devices that could not be fabricated are reliable, and hence significant further improvements could be made by fabricating these devices. Likely roles for these types of devices are medium bandwidth modulators/switches and a variety of sensor applications

Design and implementation of ultra-high speed automatic flexible controlled SOA equalizer with wide dynamic range

The research work described in this thesis focuses on the design, implementation and measurement of an analog ultra-high speed Semicondutor Optical Ampliffier (SOA) equalizer. These activities are carried out in the framework of Erasmus+ internship program. Introducing optical switching technology, it has a prospective of offering exibility, power efficiency, providing large capacity and fast response. In this thesis, the resolution of monitoring and equalization of the power for these fast optical switches is studied. Not controlling the optical power, consecutive packets may suffer large variations in the signal power level. In an optical packet switching scenario, the dynamic performance of the packets duration is so short that analog circuit has to respond with enough speed to equalize the packets in this range of time. A fast optical switch usually use semiconductor optical amplifier (SOA) as switching gates, so their utility to equalize power variation of the packets becomes increasingly attractive due to its fast nano-scale response and adjustable optical gain. The analog equalizer has to provide the correct bias current to an in-line SOA for an equal- ization of the packets in a specific sub-micron time response. This is accomplished by studying the mathematical concept of equalization up to fully design an analog circuit. Simulation of each stage as well as the whole circuit performance has been employed, showing promising results in the dynamics of the circuit, 100 ns response time. Moreover, the design of a Printed Circuit Board (PCB) layout to integrate different prototypes has also been exploited, where two prototypes has been presented: fixed-slope configuration (High-Speed Equalizer v1.0) and full- exible configura- tion (High-Speed Equalizer 2.0). In the second prototype, programmable functionalities improving the exibility of the equalizer can be supported, by updating the value of the slope and reference voltage of the scaling stage in 68 ms. Exploiting the capability of the prototype, two different regions has been tested, achieving a linear dynamic range of 10dB. Finally, a response time of 150 ns is reached by the full- exible configuration with an average power consumption of 1.3W, where the penalty is introduced by the digital potentiometers

An integrated circuit/microsystem/nano-enhanced four species radiation sensor for inexpensive fissionable material detection

Small scale radiation detectors sensitive to alpha, beta, electromagnetic, neutron radiation are needed to combat the threat of nuclear terrorism and maintain national security. There are many types of radiation detectors on the market, and the type of detector chosen is usually determined by the type of particle to be detected. In the case of fissionable material, an ideal detector needs to detect all four types of radiation, which is not the focus of many detectors. For fissionable materials, the two main types of radiation that must be detected are gamma rays and neutrons. Our detector uses a glass or quartz scintillator doped with 10B nanoparticles to detect all four types of radiation particles. Boron-10 has a thermal neutron cross section of 3,840 barns. The interaction between the neutron and boron results in a secondary charge particle in the form of an alpha particle to be emitted, which is detectable by the scintillator. Radiation impinging on the scintillator matrix produces varying optical pulses dependent on the energy of the particles. The optical pulses are then detected by a photomultiplier (PM) tube, creating a current proportional to the energy of the particle. Current pulses from the PM tube are differentiated by on-chip pulse height spectroscopy, allowing for source discrimination. The pulse height circuitry has been fabricated with discrete circuits and designed into an integrated circuit package. The ability to replace traditional PM tubes with a smaller, less expensive photomultiplier will further reduce the size of the device and enhance the cost effectiveness and portability of the detector