Optical-field emission from nanostructured solids such as subwavelength nanoantennas can be leveraged to create sub-femtosecond, petahertz-scale electronics for optical-field detection. One application of particular interest is the detection of an incident optical pulse’s carrier–envelope phase (CEP). Such CEP detection requires few-cycle, broadband optical excitation where the resonant properties of the nanoantenna can strongly alter the response of the near field in time. Little quantitative investigation has been performed to understand how the geometry and resonant properties of the antennas should be tuned to enhance the CEP sensitivity and signal-to-noise ratio. Here we examine how the geometry and resonance frequency of planar plasmonic nanoantennas can be engineered to enhance the emitted CEP-sensitive photocurrent when driven by a few-cycle optical pulse. We find that with the simple addition of curved sidewalls leading to the apex, and proper tuning of the resonance wavelength, the net CEP-sensitive current per nanoantenna can be improved by 5 − 10 × , and the signal-to-noise-ratio by 50 − 100 × relative to simple triangular antennas operated on resonance. Our findings will inform the next generation of nanoantenna designs for emerging applications in ultrafast photoelectron metrology and petahertz electronics.

Shot-to-shot, or pixel-to-pixel, dose variation during electron-beam lithography is a significant practical and fundamental problem. Dose variations associated with charging, electron source instability, optical system drift, and ultimately shot noise in the e-beam itself conspire to critical dimension variability, line width/edge roughness, and limited throughput. It would be an important improvement to e-beam based patterning technology if real-time feedback control of electron-dose were provided so that pattern quality and throughput would be improved beyond the shot noise limit. In this paper, we demonstrate control of e-beam dose based on the measurement of electron arrival at the sample where patterns are written, rather than from the source or another point in the electron optical column. Our results serve as the first steps towards real-time dose control and eventually overcoming the shot noise.

In this work, we report the use of commercial gallium nitride (GaN) power electronics to precisely switch complex distributed loads, such as electron lenses and deflectors. This was accomplished by taking advantage of the small form-factor, low-power dissipation, and high temperature compatibility of GaN field effect transistors (GaNFETs) to integrate pulsers directly into the loads to be switched, even under vacuum. This integration reduces parasitics to allow for faster switching and removes the requirement to impedance match the load to a transmission line by allowing for a lumped element approximation of the load even with subnanosecond switching. Depending on the chosen GaNFET and driver, these GaN pulsers are capable of generating pulses ranging from 100 to 650 V and 5 to 60 A in 0.25–8 ns using simple designs with easy control, few-nanosecond propagation delays, and MHz repetition rates. We experimentally demonstrate a simple 250 ps, 100 V pulser measured by using a directly coupled 2 GHz oscilloscope. By introducing resistive dampening, we can eliminate ringing to allow for precise 100 V transitions that complete a −10 to −90 V transition in 1.5 ns, limited primarily by the inductance of the oscilloscope measurement path. The performance of the pulser attached to various load structures is simulated, demonstrating the possibility of even faster switching of internal fields in these loads. We test these circuits under vacuum and up to 120 °C to demonstrate their flexibility. We expect these GaN pulsers to have broad application in fields such as optics, nuclear sciences, charged particle optics, and atomic physics that require nanosecond, high-voltage transitions.

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Graduate school is becoming a necessity for long-term success in the STEM fields. Unfortunately, many students are ill-prepared for the graduate school application process or for the graduate school experience, particularly if their undergraduate institution has only undergraduate programs, as is precisely the case at Wentworth Institute of Technology. While students at Wentworth get a first-rate undergraduate education, as well as a minimum of two semesters working in a coop , student feedback often includes being under-prepared for graduate school. To fix this deficiency among the electrical and computer Engineering and computer science and networking majors, a consortium of faculty designed, executed, and evaluated a series of extra-curricular graduate school seminars to (a) gauge student interest in graduate school, (b) prepare students for the graduate school application process, and (c) inform students of their options for graduate degrees and programs. This work-in-progress shares data and lessons-learned from the first round of seminars: we describe their organization and proceedings, as well as the results of surveys given before and after the seminars. The seminars were organized to first introduce our undergraduates, consisting largely of first-generation college students focused on job preparation, to their options for graduate school: types of degrees (MS, PhD, MBA, etc.), sources of financing (grants, assistantships, employer-assistance, etc.), application process (CV, personal statement, recommendations), and what to expect as a graduate student (research, coursework). From the seminar surveys, preliminary data reveal that students show reluctance about finances and a general lack of information. After the seminar, students felt more comfortable, claiming they are now more interested in pursuing a graduate degree (mainly MS). In order to help colleges better prepare their students for graduate school, we present our seminar organization and survey results. The work also presents tips for inspiring students and insights into the student motivation and interest in graduate school.