Optical emission spectra of the plasma generated by a 532 nm Nd：YAG laser irra- diation onto a standard aluminum alloy （E414d） was recorded and analyzed. The electron tem- perature was determined using the Boltzman...Optical emission spectra of the plasma generated by a 532 nm Nd：YAG laser irra- diation onto a standard aluminum alloy （E414d） was recorded and analyzed. The electron tem- perature was determined using the Boltzmann plot method with three aluminum spectral lines at 236.71 nm, 257.509 nm and 308.215 nm, whereas the electron density was inferred by measuring the Stark broadening line profile of Al（II） 281.619 nm. The experimental results confirmed that the local thermodynamic equilibrium was valid and the plasma was optically thin. The spectral line intensity increased initially with the increase in laser irradiance and saturated at higher Jr- radiance levels. Results showed that the energy losses due to the reflection of laser beam from the plasma itself were insignificant. The absorption in the plasma through inverse bremsstrahlung and two-photon ionization were studied. At the same timer the variation of transition probability ratio of Al（I） 309.28 nm to Al（I） 308.21 nm with laser power density was also studied.展开更多
We propose and discuss terahertz(THz) electro-optic modulator induced by periodically patterned graphene microcavity. Due to the joint effect of graphene plasmon resonances and Fabry-Perot(F-P) oscillations, plasmon-i...We propose and discuss terahertz(THz) electro-optic modulator induced by periodically patterned graphene microcavity. Due to the joint effect of graphene plasmon resonances and Fabry-Perot(F-P) oscillations, plasmon-induced transparency(PIT) effect is achieved and the operation frequency can be dynamically tuned by graphene Fermi energies and structural parameters. The results reveal that modulation depth(MD) larger than 80% is obtained across a wide frequency range from 4.2 THz to 9.4 THz, and the largest MD and Q factor reaches 95% and 15.8, respectively. In addition, operation frequency range and MD can also be tuned by optimizing the structure parameters. This investigation promises the development of high-performance widely tunable THz modulator in chip integrated photonic circuits.展开更多
The stochastic resonance based on optical bistability in the semiconductor optical amplifier is numerically investigated to extract a weak pulse signal buried in noise. The output property of optical bistability under...The stochastic resonance based on optical bistability in the semiconductor optical amplifier is numerically investigated to extract a weak pulse signal buried in noise. The output property of optical bistability under different system parameters is analyzed, which determines the performance of the stochastic resonance. Through optimizing these parameters, the noise-hidden signal is extracted via stochastic resonance, in which the maximum cross-correlation gain higher than nine is obtained. This provides a novel technology for detecting a weak optical signal in various signal processing fields.展开更多
基金supported by the Chinese Academy of Sciences/State Administration of Foreign Experts Affairs (CAS/SAFEA) International Partnership Program for Creative Research Teams
文摘Optical emission spectra of the plasma generated by a 532 nm Nd：YAG laser irra- diation onto a standard aluminum alloy （E414d） was recorded and analyzed. The electron tem- perature was determined using the Boltzmann plot method with three aluminum spectral lines at 236.71 nm, 257.509 nm and 308.215 nm, whereas the electron density was inferred by measuring the Stark broadening line profile of Al（II） 281.619 nm. The experimental results confirmed that the local thermodynamic equilibrium was valid and the plasma was optically thin. The spectral line intensity increased initially with the increase in laser irradiance and saturated at higher Jr- radiance levels. Results showed that the energy losses due to the reflection of laser beam from the plasma itself were insignificant. The absorption in the plasma through inverse bremsstrahlung and two-photon ionization were studied. At the same timer the variation of transition probability ratio of Al（I） 309.28 nm to Al（I） 308.21 nm with laser power density was also studied.
基金Supported by Scientific Research Plan Projects of Shaanxi Education Department(203011730)
文摘We propose and discuss terahertz(THz) electro-optic modulator induced by periodically patterned graphene microcavity. Due to the joint effect of graphene plasmon resonances and Fabry-Perot(F-P) oscillations, plasmon-induced transparency(PIT) effect is achieved and the operation frequency can be dynamically tuned by graphene Fermi energies and structural parameters. The results reveal that modulation depth(MD) larger than 80% is obtained across a wide frequency range from 4.2 THz to 9.4 THz, and the largest MD and Q factor reaches 95% and 15.8, respectively. In addition, operation frequency range and MD can also be tuned by optimizing the structure parameters. This investigation promises the development of high-performance widely tunable THz modulator in chip integrated photonic circuits.
基金supported by the National Natural Science Foundation of China under Grant No.61275134
文摘The stochastic resonance based on optical bistability in the semiconductor optical amplifier is numerically investigated to extract a weak pulse signal buried in noise. The output property of optical bistability under different system parameters is analyzed, which determines the performance of the stochastic resonance. Through optimizing these parameters, the noise-hidden signal is extracted via stochastic resonance, in which the maximum cross-correlation gain higher than nine is obtained. This provides a novel technology for detecting a weak optical signal in various signal processing fields.
