Intellectual Merit: Mode-locked lasers generate periodic trains of ultrashort pulses that are characterized in the frequency domain by an evenly spaced series of discrete spectral lines. Recently, the stabilization of such optical frequency combs has led to a direct and precise connection between frequencies spanning radio-frequency to optical and to enormous progress in precision optical frequency synthesis and metrology. In parallel, pulse shaping techniques that exploit frequency domain manipulation of optical spectral components for synthesis of user-specified ultrashort pulsed fields have been developed and widely adopted. Until now frequency stabilization of mode-locked lasers and frequency domain manipulation and shaping of such lasers have been considered separately. Therefore, a new research program is planned in which high resolution pulse shapers resolve and control individual spectral lines. The envisioned research includes investigation of pulse shaping in the line-by-line regime, with an emphasis on new phenomena arising from line-by-line manipulation; demonstration of waveform characterization methods appropriate for line-by-line pulse shaping; development of novel pulse shaper geometries capable of very high resolution (GHz range) while scaling to manipulation of thousands of lines; and investigation of comb sources providing increased numbers of spectral lines while maintaining good optical frequency stability in a parameter range suitable for applications in optical telecommunications.
Broader Impacts: The planned research on manipulation of individual spectral lines is expected to lead to a fundamentally new regime in ultrafast optics in which the attributes and advantages of pulse shaping and of stabilized frequency combs can be simultaneously realized and exploited for the first time. Both optical pulse shaping and femtosecond frequency combs technologies have individually had tremendous impact. Combining them should result in new opportunities in areas such as secure optical communications, ultrawideband electrical waveform generation for radar and wireless communications, coherent control of chemical reactions and quantum mechanical motions, single cycle pulse generation, and spectroscopy. Because these technologies are broadly enabling, it is likely that additional applications as yet unanticipated will also emerge. This project should also provide rich opportunities for broad student training in areas of cutting-edge technology, within the atmosphere of a leading research group whose excellence in graduate student training is evidenced through a strong record of student awards. Two Ph.D. students are included in the proposal budget. These students will have the opportunity to design, implement, and test novel optical pulse shaping and frequency comb modules and perform experiments integrating these advanced technologies, as well as report their findings and interact with other researchers at appropriate conference venues.
