First-principles analyses are performed on the diamond europium vacancy (EuV) color center. Three different models indicate that the structure of the EuV color center contains a stable vacancy around the Eu atom. Energy band calculations show that the stable EuV color center has spin polarization and its spin-up energy level structure is highly suitable as a single-photon source. The zero-point transition energy is 1.989 eV (623 nm). The existence of metastable energy levels in the EuV is also predicted. Nitrogen atoms have a negative impact on the electronic structure of the EuV, in comparison to diamond color centers such as NE8 and TiV-N.First-principles analyses are performed on the diamond europium vacancy (EuV) color center. Three different models indicate that the structure of the EuV color center contains a stable vacancy around the Eu atom. Energy band calculations show that the stable EuV color center has spin polarization and its spin-up energy level structure is highly suitable as a single-photon source. The zero-point transition energy is 1.989 eV (623 nm). The existence of metastable energy levels in the EuV is also predicted. Nitrogen atoms have a negative impact on the electronic structure of the EuV, in comparison to diamond color centers such as NE8 and TiV-N.

Optical Materials ExpressNov 18, 20202 citations

Role of atomic coherence effects in four-wave mixing using autoionizing resonances

M. Anscombe, Rebeca de Nalda, İbrahim Küçükkara +1 more

The generation of tunable, nanosecond-pulsed extreme-ultraviolet (EUV) light $(84.92\mathrm{nm}$ to $84.97\mathrm{nm}$ $\ensuremath{\sim}14.6\mathrm{eV})$ using four-wave mixing in optically deep krypton gas was investigated experimentally and theoretically. The sum-frequency mixing scheme generated light from two overlapping autoionizing resonances, ${17s}^{\ensuremath{'}}$ and ${15d}^{\ensuremath{'}}$. We investigated whether the laser-induced atomic coherence effect of electromagnetically induced transparency (EIT) could enhance the intensity of the EUV light generated. The maximum EUV output was seen from the region where the ${15d}^{\ensuremath{'}}$ autoionizing resonance has a transparency window due to Fano-type quantum interference. An analytical model using appropriate atomic parameters explains how background absorption can prevent EIT enhancement of EUV generation; and shows how a background Raman-like coupling term in the nonlinear susceptibility can well describe the measured EUV generation spectrum.The generation of tunable, nanosecond-pulsed extreme-ultraviolet (EUV) light $(84.92\mathrm{nm}$ to $84.97\mathrm{nm}$ $\ensuremath{\sim}14.6\mathrm{eV})$ using four-wave mixing in optically deep krypton gas was investigated experimentally and theoretically. The sum-frequency mixing scheme generated light from two overlapping autoionizing resonances, ${17s}^{\ensuremath{'}}$ and ${15d}^{\ensuremath{'}}$. We investigated whether the laser-induced atomic coherence effect of electromagnetically induced transparency (EIT) could enhance the intensity of the EUV light generated. The maximum EUV output was seen from the region where the ${15d}^{\ensuremath{'}}$ autoionizing resonance has a transparency window due to Fano-type quantum interference. An analytical model using appropriate atomic parameters explains how background absorption can prevent EIT enhancement of EUV generation; and shows how a background Raman-like coupling term in the nonlinear susceptibility can well describe the measured EUV generation spectrum.

Physical Review AOct 8, 20032 citations

Absorption and emission of single attosecond light pulses in an autoionizing gaseous medium dressed by a time-delayed control field

Wei-Chun Chu, C. D. Lin

An extreme ultraviolet (EUV) single attosecond pulse passing through a laser-dressed dense gas is studied theoretically. The weak EUV pulse pumps the helium gas from the ground state to the $2s2p({}^{1}P)$ autoionizing state, which is coupled to the $2{s}^{2}{(}^{1}S)$ autoionizing state by a femtosecond infrared laser with the intensity in the order of 10 ${}^{12}$ W/cm ${}^{2}$ . The simulation shows how the transient absorption and emission of the EUV are modified by the coupling laser. A simple analytical expression for the atomic response derived for $\ensuremath{\delta}$-function pulses reveals the strong modification of the Fano lineshape in the spectra, where these features are quite universal and remain valid for realistic pulse conditions. We further account for the propagation of pulses in the medium and show that the EUV signal at the atomic resonance can be enhanced in the gaseous medium by more than 50 $%$ for specifically adjusted laser parameters, and that this enhancement persists as the EUV propagates in the gaseous medium. Our result demonstrates the high-level control of nonlinear optical effects that are achievable with attosecond pulses.An extreme ultraviolet (EUV) single attosecond pulse passing through a laser-dressed dense gas is studied theoretically. The weak EUV pulse pumps the helium gas from the ground state to the $2s2p({}^{1}P)$ autoionizing state, which is coupled to the $2{s}^{2}{(}^{1}S)$ autoionizing state by a femtosecond infrared laser with the intensity in the order of 10${}^{12}$ W/cm${}^{2}$. The simulation shows how the transient absorption and emission of the EUV are modified by the coupling laser. A simple analytical expression for the atomic response derived for $\ensuremath{\delta}$-function pulses reveals the strong modification of the Fano lineshape in the spectra, where these features are quite universal and remain valid for realistic pulse conditions. We further account for the propagation of pulses in the medium and show that the EUV signal at the atomic resonance can be enhanced in the gaseous medium by more than 50$%$ for specifically adjusted laser parameters, and that this enhancement persists as the EUV propagates in the gaseous medium. Our result demonstrates the high-level control of nonlinear optical effects that are achievable with attosecond pulses.

arXiv:1211.6172Physical Review AJan 16, 201345 citations

4p-L-8 Eu^+の光電離過程

睦佐野, 陽伊藤, 正樹大浦 +7 more

日本物理学会講演概要集. 秋の分科会Aug 16, 19940 citations

The generation of tunable, nanosecond-pulsed extreme-ultraviolet (EUV) light

(84.92\mathrm{nm}

84.97\mathrm{nm}

$\ensuremath{\sim}14.6\mathrm{eV})$ using four-wave mixing in optically deep krypton gas was investigated experimentally and theoretically. The sum-frequency mixing scheme generated light from two overlapping autoionizing resonances, ${17s}^{\ensuremath{'}}$ and ${15d}^{\ensuremath{'}}$. We investigated whether the laser-induced atomic coherence effect of electromagnetically induced transparency (EIT) could enhance the intensity of the EUV light generated. The maximum EUV output was seen from the region where the ${15d}^{\ensuremath{'}}$ autoionizing resonance has a transparency window due to Fano-type quantum interference. An analytical model using appropriate atomic parameters explains how background absorption can prevent EIT enhancement of EUV generation; and shows how a background Raman-like coupling term in the nonlinear susceptibility can well describe the measured EUV generation spectrum.

An extreme ultraviolet (EUV) single attosecond pulse passing through a laser-dressed dense gas is studied theoretically. The weak EUV pulse pumps the helium gas from the ground state to the

2s2p({}^{1}P)

autoionizing state, which is coupled to the

2{s}^{2}{(}^{1}S)

autoionizing state by a femtosecond infrared laser with the intensity in the order of 10

{}^{12}

W/cm

{}^{2}

. The simulation shows how the transient absorption and emission of the EUV are modified by the coupling laser. A simple analytical expression for the atomic response derived for $\ensuremath{\delta}$-function pulses reveals the strong modification of the Fano lineshape in the spectra, where these features are quite universal and remain valid for realistic pulse conditions. We further account for the propagation of pulses in the medium and show that the EUV signal at the atomic resonance can be enhanced in the gaseous medium by more than 50

%

for specifically adjusted laser parameters, and that this enhancement persists as the EUV propagates in the gaseous medium. Our result demonstrates the high-level control of nonlinear optical effects that are achievable with attosecond pulses.