We counteracted gain narrowing effects in an ultrafast CPA laser undergoing an upgrade. We used Fastlite’s DAZZLER to shape the pulse spectrum before amplification. We automated the process in LABVIEW. The upgraded laser should demonstrate an increase in peak power from 10 TW to 17.8 TW using this process. Supported by NSF.
We report amplitude and frequency noise measurements of an injection-locked ti:sapphire laser which is used to amplify a low power diode laser to Watt-level output powers. Frequency noise is measured using heterodyne techniques. We find a frequency width of 360 kHz and an rms amplitude noise level of 1%.
We examined experimentally dynamical behaviors (e. g., polarization switching, frequency locking and periodic oscillation) of a VCSEL operating in the multi-transverse mode regime under orthogonal optical injection. The dynamics of the VCSEL is mapped in the parameter plane of frequency detuning versus injected power. Supported by Bates College.
We have investigated a geometric phase arising from cyclic transformations on a recently-proposed higher-order Poincaré sphere representation of vector states of polarization and total optical angular momentum. The measured geometric phase is shown to be directly proportional to the beam's total optical angular momentum.
Monitoring and analysis of food additives become an urgent need for ensuring food safety for consumers. The combination of Raman and infrared spectroscopic signatures were used to characterize different carotenoids for food coloring. Results showed identification and discrimination of tested carotenoid species were possible through Raman and IR spectroscopy. Supported by NSF-REU.
We employ an interferometric technique to diagnose the plasma density in the focus of an intense laser ionizing argon. The plasma density is characterized as a function of delay after the ionizing pulse.
We have created scattering structures in transparent materials using ultrafast lasers. Due to the micron scale size of the individual structures and the nature of their creation, true 3D geometry with a large variation in size is achievable. Supported by NSF IREU.
As part of an effort to demonstrate adiabatic quantum computing with neutral cesium atoms, we have developed laser systems necessary for optical pumping, tuning hyperfine transitions via the light shift, and coherently exciting to Rydberg levels. Frequency stabilization to a cesium reference is achieved via offset or cavity transfer locks.
We study the formation of quantum dots on silicon wafers using Laser Induced Breakdown Spectroscopy, and the Fresnel Equations for reflection of light from a metal. Quantum dots have applications as ultra-fast, environmentally-friendly detectors, and in nanomedicine as carriers of treatments to specific parts of the body. Supported by URSI.
We studied the properties of an Engineered Diffuser™, an array of individually designed and arranged microlenses that produces a particular pattern of light (a square in our case). Using different color lasers, polarizations, beam diameters, and convergences, we measured output beam shape, convergence, polarization, and intensity distribution. Supported by ONR and NASA.
Optical frequency combs based on nonlinear parametric conversion in microresonators have been recently developed. We are working towards all-optical stabilization of microresonator frequency combs (microcombs) to the Doppler-free transitions of atomic Rb. Microcombs have applications in the development of chip-sized atomic clocks. Supported by NSF, NIST, DARPA, and NRC.
The Science Outreach Catalyst Kits ? or SOCKs ? have been produced each summer by Society of Physics Students interns since 2001 at the American Center for Physics. These kits are an assembly of physics experiments and demonstrations to be sent to various SPS chapters to help jump-start an outreach program. This year was the 50th anniversary of the laser, so the theme of the SOCK was geared towards lasers and optics. It contains a laser demonstration, an optics/lens activity, and an activity to test rolling speeds of different objects. This presentation will serve to show what went into the 2010 SOCKS, as well as highlight the preparation and testing involved in their production.
In our continuing effort to stimulate young minds and encourage interest in physics among K12 school children, the Angelo State Society of Physics Students Peer Pressure Team science outreach group embarked on its 6th annual week-long outreach trip across west Texas. Ten undergraduate physics students ranging from freshman to veteran seniors visited 8 public schools to present physics demonstrations including several new additions to celebrate Laserfest 2010. In this poster we detail our experiences and discuss the feedback we received from audience participants.
Parallel-plate waveguides are among the most common low-loss broadband waveguides in the terahertz frequency regime. One application is microfluidic detection. Adding a groove into one of the waveguide plates leads to a resonant feature of relatively high quality factor (Q-factor), that shifts to different frequencies when the groove is filled with different liquids. We investigate the resonant frequencies and transmission characteristics of different-sized grooves in aluminum plates in order to determine which groove is most suitable for microfluidic sensing. This apparatus is formed by machining grooves of varying geometries into aluminum plates, which are then used to form parallel-plate waveguides. Sub-picosecond terahertz pulses are used to excite the lowest-order transverse-electric (TE1) mode. The output spectrum is analyzed to determine resonant frequency and Q-factor for each groove geometry, then used to determine which groove gives the highest Q-factor, thus increasing the sensitivity of a groove-based microfluidic sensor.
Peer-led team learning (PLTL) workshops supplement lecture courses by facilitating a supportive environment for students to actively participate in the process of learning undergraduate level general chemistry and general physics at many colleges and universities. Under the PLTL model, successful students are recruited and trained as workshop leaders. These students guide a group of six to 10 students on selected problems to build conceptual understanding and problem-solving skills. In this presentation, we report on the PLTL workshop experience for both general chemistry and physics workshops at Portland State University. Student evaluation data from both workshops are compared. In addition, qualitative data from workshop leaders and students are presented. Finally, strategies for engaging students, facilitating a positive environment, and addressing special situations are discussed.
We are developing an FCI -style assessment covering hydrostatic topics commonly included in introductory physics courses. Our goal is for the assessment to provide meaningful analysis of student learning for a wide range of populations, from conceptual-based courses through honors calculus-based courses. One hydrostatic topic students in these populations should understand is how the pressures at different points in a fluid compare. This poster presents our efforts to craft a series of questions that distinguishes correct physical understanding from common misconceptions expressed by students.
Beginning my studies in the fall of 2007 at Cleveland State University (CSU) I had a very broad list of subjects I was interested in and no real clue of what profession I wanted to pursue. After two semesters of studying the sciences I was leaning towards physics?based in large part on my interest in how the fundamental ideas of 2-hour lab experiments could be manipulated to study cross-disciplinary research topics. So I declared my major and applied for teaching assistant and research assistant positions, both of which I started in the summer of 2008. My teaching position has allowed me to take a fresh new look at basic physics?keeping me grounded in my basic knowledge and allowing me to see connections between the fundamentals and my upper level coursework. I truly believe that the best way to really learn is to teach, so teaching lab courses is an ideal job for a physics major! Participating in research projects through summer undergraduate research at CSU and an REU at the University of Akron has also made a remarkable impact on my studies by allowing me to explore applications and applied theories of the broader subject matter of my courses. My career ambitions have been dramatically shaped by actively participating in research and traveling all over the country to conferences where I was surrounded by students in my shoes and by professors and researchers who have made it to the point I?m working towards now. My poster will explore how these teaching and research opportunities have molded my attitude as a student, have impacted my understanding of upper-level class materials, and have reinforced my ambitions to study physics and to one day become a professor, perhaps with a focus on Physics Education.
We present information regarding two LaserFest events that happened at our home institution (IPFW). Over the past summer (2010) we ran a day camp for high school age students as well as a workshop for high school teachers. The day camp had several purposes: to teach kids about lasers as well as providing ?fun? activities featuring lasers. The workshop was designed to have the teachers learn more about lasers and light so that they can incorporate them into their classes. We will present information regarding the activities we developed.
In order to formalize Angelo State University Physics science outreach, we have partnered with a local elementary school to develop three hands-on labs for 5th grade students. The local elementary school was selected after a previous collaboration with the Angelo State Society of Physics Students (SPS) can roll service project. Project goals were aimed at helping with limited physical science resources available at the school and to encourage underrepresented groups to study science. Each lab was presented by Angelo State SPS undergraduate physics majors. Collaboration with the school science coordinator helped direct our efforts to those areas identified as in need of improvement, including motion, energy and optics. Labs were structured toward science criteria in the Texas Essential Knowledge and Skills (TEKS) in order to supplement student instruction in these topics. Pre- and post-lab assessments were analyzed in order to gauge the effectiveness of our efforts.
We report a systematic measurement of the electron-phonon thermalization timescales as a function of the sample base temperature in Ni using femtosecond electron diffraction. A strong temperature dependence has been observed in the vicinity of the Curie point. By assuming that ultrafast demagnetization completes well before the electron-phonon thermalization, this correlation between thermalization time and sample base temperature can be fit by a modified three temperature model describing the energy transfer among charge, spin and phonon subsystems. The results indicate that charges and spins can be characterized by a unified temperature during ultrafast lattice heating. *I was invited to be part of this research project as part of my Research Experience for Teachers program sponsored by The National High Magnetic Field Lab on the campus of Florida State University. I participated in the experimentation during the Summer of 2009. The paper on this experiement was published in Physical Review B 81, 220301 (R) (2010).