We experimentally demonstrate robust selective excitation and attenuation of atomic Rydberg level populations in sodium vapor (Na i) using intense laser pulses in the strong-field limit $(>{10}^{12}\phantom{\rule{0.16em}{0ex}}\mathrm{W}/\mathrm{c}{\mathrm{m}}^{2})$ . Coherent control of the atomic population and related ionization channels is realized for intensities above the over-the-barrier ionization intensity. Moreover, atomic excitation selectivity and high ionization yield are simultaneously achieved without the need to tailor the spectral phase of the laser. A qualitative model confirms that this strong-field coherent control arises through the manifestation of a Freeman resonance.We experimentally demonstrate robust selective excitation and attenuation of atomic Rydberg level populations in sodium vapor (Na i) using intense laser pulses in the strong-field limit $(>{10}^{12}\phantom{\rule{0.16em}{0ex}}\mathrm{W}/\mathrm{c}{\mathrm{m}}^{2})$. Coherent control of the atomic population and related ionization channels is realized for intensities above the over-the-barrier ionization intensity. Moreover, atomic excitation selectivity and high ionization yield are simultaneously achieved without the need to tailor the spectral phase of the laser. A qualitative model confirms that this strong-field coherent control arises through the manifestation of a Freeman resonance.

arXiv:1509.04571Physical Review AJun 28, 201627 citations

Selective Strong-Field Enhancement and Attenuation of Excitation and Ionization with Short Laser Pulses

N. A. Hart

The coherent control of atomic energy level population is important for several areas physics and engineering including fluorescent spectroscopy, resonantly enhanced multiphoton ionization, harmonic generation, remote sensing and lasing. At low intensities where the Stark shift can be neglected, coherent control mechanisms usually exploit resonances created from stationary energy states dressed by integer multiples of the photon energy. However, in the strong field limit where large laser pulse intensities lead to significant Stark shifts, the resonant conditions are dynamic both in time and space and will likely not be satisfied for the entire laser pulse or beam.\n\nIn this research, we experimentally and theoretically demonstrate coherent control of atomic energy level population in sodium vapor as well as the selective excitation of sodium Rydberg levels using high intensity laser pulses. We also make a direct measurement of the ponderomotive shift of the continuum. While techniques based on resonance interferences and rapid adiabatic passage have been introduced for selective excitation, the conditions that must be satisfied for these phenomena can be hampered by short femtosecond pulse durations and large Stark shifts. In contrast, a technique referred to here as Resonance Sampling, uses the AC Stark shifts to selectively induce Freeman resonances and is resilient to changes in the spectral phase. Freeman resonances established in this way can result in population inversion of the excited state, and may lead to new lasing mediums and remote sensing applications.\n\n\nIn this research, we experimentally and theoretically demonstrate coherent control of atomic energy level population in sodium vapor as well as the selective excitation of sodium Rydberg levels using high intensity laser pulses. While techniques based on resonance interferences and rapid adiabatic passage have been introduced for selective excitation, the conditions that must be satisfied for these phenomena can be hampered by short femtosecond pulse durations and large Stark shifts. In contrast, a technique referred to here as Resonance Sampling, uses the AC Stark shifts to selectively induce Freeman resonances and is resilient to changes in the spectral phase. Freeman resonances established in this way can result in population inversion of the excited state, and may lead to new lasing mediums and remote sensing applications.The coherent control of atomic energy level population is important for several areas physics and engineering including fluorescent spectroscopy, resonantly enhanced multiphoton ionization, harmonic generation, remote sensing and lasing. At low intensities where the Stark shift can be neglected, coherent control mechanisms usually exploit resonances created from stationary energy states dressed by integer multiples of the photon energy. However, in the strong field limit where large laser pulse intensities lead to significant Stark shifts, the resonant conditions are dynamic both in time and space and will likely not be satisfied for the entire laser pulse or beam.\n\nIn this research, we experimentally and theoretically demonstrate coherent control of atomic energy level population in sodium vapor as well as the selective excitation of sodium Rydberg levels using high intensity laser pulses. We also make a direct measurement of the ponderomotive shift of the continuum. While techniques based on resonance interferences and rapid adiabatic passage have been introduced for selective excitation, the conditions that must be satisfied for these phenomena can be hampered by short femtosecond pulse durations and large Stark shifts. In contrast, a technique referred to here as Resonance Sampling, uses the AC Stark shifts to selectively induce Freeman resonances and is resilient to changes in the spectral phase. Freeman resonances established in this way can result in population inversion of the excited state, and may lead to new lasing mediums and remote sensing applications.\n\n\nIn this research, we experimentally and theoretically demonstrate coherent control of atomic energy level population in sodium vapor as well as the selective excitation of sodium Rydberg levels using high intensity laser pulses. While techniques based on resonance interferences and rapid adiabatic passage have been introduced for selective excitation, the conditions that must be satisfied for these phenomena can be hampered by short femtosecond pulse durations and large Stark shifts. In contrast, a technique referred to here as Resonance Sampling, uses the AC Stark shifts to selectively induce Freeman resonances and is resilient to changes in the spectral phase. Freeman resonances established in this way can result in population inversion of the excited state, and may lead to new lasing mediums and remote sensing applications.

May 12, 20150 citations

We experimentally demonstrate robust selective excitation and attenuation of atomic Rydberg level populations in sodium vapor (Na i) using intense laser pulses in the strong-field limit

(>{10}^{12}\phantom{\rule{0.16em}{0ex}}\mathrm{W}/\mathrm{c}{\mathrm{m}}^{2})

. Coherent control of the atomic population and related ionization channels is realized for intensities above the over-the-barrier ionization intensity. Moreover, atomic excitation selectivity and high ionization yield are simultaneously achieved without the need to tailor the spectral phase of the laser. A qualitative model confirms that this strong-field coherent control arises through the manifestation of a Freeman resonance.