In the past several decades the technology for the creation and use of ultrashort pulses has progressed tremendously. Now, it is possible to generate laser pulses as short as a few femtoseconds in duration, and such pulses have been used for a wide range of applications. In addition, the means of measuring these pulses has progressed so rapidly. However, despite recent great advances in ultrashort-pulse measurement techniques, much remains to be done. In particular, pulse-measurement devices have relatively small wavelength-tuning ranges, and the phase-match is problematic for the pulses with a wide bandwidth such as supercontinuum. In this thesis, I will demonstrate a new pulse measurement technique which can phase-match ultra-broad bandwidth of super-continuum using transient grating frequency-resolved-optical-gating (TG FROG). Also, I will demonstrate a simplified device which can measure the UV ultra-short pulse using transient grating process, one of the third-order nonlinearity and can cover from UV to IR with the same arrangement.

Thermal switch is very important in today’s world and it has varies of applications including heat dissipation and engine efficiency improving. The commercial thermal switch based on mechanical design is very slow and the structure is too complicated to make them smaller. To enable fast thermal switch as well as to make thermal switch more compact, I try to use second-order phase transition material to enable our thermal switch. Noticing the transition properties of thermoresponsive polymer for drug delivery, its potential in thermal switch can be expected. I used Poly(N-isopropylacrylamide) (PNIPAM) as an example to show the abrupt thermal conductivity change of thermoresponsive polymer solutions below and above their phase transition temperature. A novel technique, transition grating method, is used to measure the thermal conductivity. The ratio of thermal switch up to 1.15 in transparent PNIPAM solutions after the transition is observed. This work will demonstrate the new design of using second-order phase transition material to enable fast and efficient thermal switch. / Master of Science / Controllable thermal conductivity (thermal switching) is very important to thermal management area and useful in a wide area of applications. Nowadays, mechanical thermal conductivity controller device suffers from large scale and slow transition speeds. To solve these problems, I tired the phase transition thermoresponsive polymers to create quick thermal switching because the thermal conductivity will change with the phase. Thermoresponsive polymers show sharp phase changes upon small changes in temperature. Such polymers are already widely used in biomedical-like applications, the thermal switch applications are not well-studied. In this work, I tested Poly(N-isopropylacrylamide) (the abbreviation is PNIPAM) as an example to show the quick thermal conductivity changing ability of thermoresponsive polymer when the transition was happened .I used a novel approach, called the TTG, transient thermal grating. It has easy setup and high sensitivity. The thermal conductivity switching ratio as high as 1.15 in transparent PNIPAM solutions after transition is observed. This work will give new opportunities to control thermal switches using the phase change of thermoresponsive material or abrupt other phase change material in general.

This thesis describes a method developed to quickly measure the Rayleigh wave Q for a test material using a minimally invasive laser probe. The probe was donated to our lab by Dr. Alex Maznev at Phillips AMS in Natick, Ma. The machine was originally used to measure ultra thin film metal thicknesses; however we have utilized it to suit our needs. The optics head relies on a technique known as the transient grating method to generate a dispersion curve. This dispersion curve is then operated on by a local approximation for the Kramers-Kronig relations. The Kramers-Kronig relations for acoustic waves relate the real and imaginary parts of the dynamic compressibility to one another. The real part of the compressibility relates to the phase velocity of the wave and the imaginary part relates to the attenuation. Once the attenuation for the corresponding range of frequencies is determined the last step is to apply both the dispersion data and the attenuation data to the material Q equation to find Q over a range of frequencies. This thesis discusses the design of the machine, the theory behind the Kramers-Kronig relations and surface acoustic waves, the experimental procedure, and lastly results generated by the technique.

Azo-Dye Doped Liquid Crystal (DDLC) is a developed material which can be used to fabricate optical shutter, displays, etc. In this thesis, we presents of the transient grating on a planar aligned DDLC. The effect of various polarizations of writing and probing beams, and of temperature on the transient grating are examined. Then, we propose a model to explain the result. Through this study, we understand the factors that determine the light-induced aligning Dye effect on nematic liquid crystals.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第21595号 / 理博第4502号 / 新制||理||1646(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 寺嶋 正秀, 教授 林 重彦, 教授 竹腰 清乃理 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

京都大学 / 新制・課程博士 / 博士(理学) / 甲第23033号 / 理博第4710号 / 新制||理||1675(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 寺嶋 正秀, 教授 林 重彦, 教授 渡邊 一也 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

京都大学 / 新制・課程博士 / 博士(理学) / 甲第23723号 / 理博第4813号 / 新制||理||1689(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 寺嶋 正秀, 教授 林 重彦, 教授 渡邊 一也 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

京都大学 / 新制・課程博士 / 博士(理学) / 甲第23031号 / 理博第4708号 / 新制||理||1675(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 寺嶋 正秀, 教授 林 重彦, 教授 渡邊 一也 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

京都大学 / 新制・課程博士 / 博士(理学) / 甲第23720号 / 理博第4810号 / 新制||理||1688(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 寺嶋 正秀, 教授 林 重彦, 教授 渡邊 一也 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

Semiconductor nanostructures exhibit many remarkable electronic and optical properties. The key to designing and utilising semiconductor quantum structures is a physical understanding of the detailed excitation, transport and energy relaxation processes. Thus the nonequilibrium dynamics of semiconductor quantum structures have attracted extensive attention in recent years. Ultrafast spectroscopy has proven to be a versatile and powerful tool for investigating transient phenomena related to the relaxation and transport dynamics in semiconductors. In this thesis, we report investigations into the electronic and optical properties of various semiconductor quantum systems using a variety of ultrafast techniques, including up-conversion photoluminescence, pump-probe, photon echoes and four-wave mixing. The semiconductor quantum systems studied include ZnO/ZnMgO multiple quantum wells with oxygen ion implantation, InGaAs/GaAs self-assembled quantum dots with different doping, InGaAs/InP quantum wells with proton implantation, and silicon quantum dots. The spectra of these semiconductor nanostructures range from the ultraviolet region, through the visible, to the infrared. In the UV region we investigate excitons, biexcitons and oxygen implantation effects in ZnO/ZnMgO multi-quantum wells using four-wave mixing, pump-probe and photoluminescence techniques. Using time-resolved up-conversion photoluminescence, we investigate the relaxation dynamics and state filling effect in InGaAs self-assembled quantum dots with different doping, and the implantation effect in InGaAs/InP quantum wells. Finally, we study the optical properties of silicon quantum dots using time-resolved photoluminescence and photon echo spectroscopy on various time scales, ranging from microseconds to femtoseconds.