An official website of the United States government
A pulse generation scheme is proposed based on a structured resonance in a cavity where the non-conventional energy distribution is concentrated in its middle part. The cavity is first used as an oscillator during the energy charging step and when a switch is activated the signal is extracted from its center. The key component of the proposed scheme is the periodic microstrip waveguide with a fourth-order degenerate band edge (DBE) of its wavenumber-frequency dispersion diagram. The DBE is an exceptional point degeneracy condition that is responsible for the energy to be localized at the cavity center and that can also have the quality factor easily destroyed by a perturbation. The waveguide is designed to have a DBE frequency of 2.86 GHz and produces pulses of approximately 0.1 V peak and 1.1 ns width.
more »
« less
Pulse Generation using a Degenerate Band Edge Structure
We propose a pulse generation scheme based on a fourth-order degeneracy in the dispersion relation. We take advantage of the loaded quality factor enhancement and the ultra-sensitivity to external perturbations due to the high order degeneracy in such a structure. The proposed scheme is able to produce a train of nanosecond pulses with several watts of output power. Such a design offers a flexibility that allows to conceive either high output power pulses or high frequency train of pulses.
more »
« less
- Award ID(s):
- 1711975
- PAR ID:
- 10156735
- Date Published:
- Journal Name:
- 2019 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting, Atlanta, GA, USA, 7-12 July 2019.
- Page Range / eLocation ID:
- 1181 to 1182
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract High‐bandwidth metallic coaxial nanolasers are of high interest to investigate laser physics such as thresholdless coherence transitions, and have a large variety of promising applications enabled by their ultrasmall size and large spectral bandwidth. Optical coherence properties are commonly characterized in Hanbury‐Brown and Twiss experiments. However, those are difficult to perform in broadband lasers when the coherence time is an order of magnitude shorter than the temporal resolution of the single‐photon detectors, thus requiring significant spectral filtering. This paper demonstrates a new approach in investigating the temporal dynamics of the photon statistics associated with the nanolaser emission, obtained without the requirement of spectral filtering. While optically pumping the nanolasers with nanosecond pulses, time‐resolved second‐order coherence properties are evaluated over the time duration of the pump pulse. Coherence transitions from thermal emission to lasing are observed in the gathered time‐resolved photon statistics, linked to the temporal change in optical power of the nanosecond pump pulses. As nanolasers show better performance for the pulsed pumping scheme, the temporal envelope modulation of these pulses results in varying degrees of coherence within the nanolaser pulse envelope. This approach can also be readily applied to characterize a large variety of broadband lasers.more » « less
-
The shortest light pulses produced to date are of the order of a few tens of attoseconds, with central frequencies in the extreme UV range and bandwidths exceeding tens of electronvolts. They are often produced as a train of pulses separated by half the driving laser period, leading in the frequency domain to a spectrum of high, odd-order harmonics. As light pulses become shorter and more spectrally wide, the widely used approximation consisting of writing the optical waveform as a product of temporal and spatial amplitudes does not apply anymore. Here, we investigate the interplay of temporal and spatial properties of attosecond pulses. We show that the divergence and focus position of the generated harmonics often strongly depend on their frequency, leading to strong chromatic aberrations of the broadband attosecond pulses. Our argument uses a simple analytical model based on Gaussian optics, numerical propagation calculations, and experimental harmonic divergence measurements. This effect needs to be considered for future applications requiring high-quality focusing while retaining the broadband/ultrashort characteristics of the radiation.more » « less
-
Abstract High-order harmonic generation (HHG) has become an indispensable process for generating attosecond pulse trains and single attosecond pulses used in the observation of nuclear and electronic motion. As such, improved control of the HHG process is desirable, and one such possibility for this control is through the use of structured laser pulses. We present numerical results from solving the one-dimensional time-dependent Schrödinger equation for HHG from hydrogen using Airy and Gaussian pulses that differ only in their spectral phase. Airy pulses have identical power spectra to Gaussian pulses, but different spectral phases and temporal envelopes. We show that the use of Airy pulses results in less ground state depletion compared to the Gaussian pulse, while maintaining harmonic yield and cutoff. Our results demonstrate that Airy pulses with higher intensity can produce similar HHG spectra to lower intensity Gaussian pulses without depleting the ground state. The different temporal envelopes of the Gaussian and Airy pulses lead to changes in the dynamics of the HHG process, altering the time-dependence of the ground state population and the emission times of the high harmonics. Graphical abstractmore » « less
-
Synopsis We suggest a technique to amplify a train of attosecond pulses, produced via high-harmonic generation of an infrared laser field, in active medium of a plasma-based X-ray laser driven by a replica of the same IR field as used to produce high harmonics forming a train of attosecond pulses.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/APUSNCURSINRSM.2019.8888693
