Generation of third-order harmonics at 800 nm of femtosecond laser pulses is studied in neutral atmospheric air and in plasma of optical breakdown in air.Its efficiency is measured at different fundamental laser inten...Generation of third-order harmonics at 800 nm of femtosecond laser pulses is studied in neutral atmospheric air and in plasma of optical breakdown in air.Its efficiency is measured at different fundamental laser intensities.A maximum efficiency is observed at the intensity when optical breakdown in atmospheric air starts.The factors that exhibit the main effects on the harmonic generation,including self-focusing in a neutral air and self-focusing in plasma,are discussed.展开更多
The temporal behaviour and spectral distribution of white-light continuum generation in H2O using a focused intense 800 nm 130 fs Ti:Sapphire laser were studied.The results indicated that the white-light continuum spe...The temporal behaviour and spectral distribution of white-light continuum generation in H2O using a focused intense 800 nm 130 fs Ti:Sapphire laser were studied.The results indicated that the white-light continuum spectrally ranged from 1000 to 400 nm,which was mainly attributed to self-phase modulation related to Kerr effect and ionization.The pulse duration of different spectral components of the generated white-light continuum,which was measured with frequency up-conversion technique,was obtained around 137 fs.It revealed a comparable time resolution as the original laser pulse.展开更多
Supercontinuum generation in atmospheric-pressure nitrogen by a focused intense femtosecond Ti:sapphire laser was studied at various pulse durations and energies.The generated supercontinuum was greatly blue-broadened...Supercontinuum generation in atmospheric-pressure nitrogen by a focused intense femtosecond Ti:sapphire laser was studied at various pulse durations and energies.The generated supercontinuum was greatly blue-broadened due to self-phase modulation in the plasma produced.The measured blue-broadening△ωis proportional to pulse intensity for fixed pulse duration,and values up to 0.7ω(ωbeing the originaI laser frequency)was obtained with a pulse energy of 9.5 mJ and minimum duration of 100 fs.展开更多
We have studied the plasma generation through collecting the charged particles produced in laser-induced break-down in atmospheric air.This breakdovn is produced by ultrashort laser pulses with various durations rangi...We have studied the plasma generation through collecting the charged particles produced in laser-induced break-down in atmospheric air.This breakdovn is produced by ultrashort laser pulses with various durations ranging from 200fs to 2ps at a fixed pulse energy of 8mJ.We found that the plasma yield increases first with the increment of pulse duration and then reaches a plateau at a duration longer than 500fs.The generated plasma temperature is estimated to be higher than 5x 10^(5)K.展开更多
基金Supported by National Key Basic Research Special Foundation under Grant No.G1999075207the National Natural Science Foundation of China under Grant Nos.19884001 and 19525412.
文摘Generation of third-order harmonics at 800 nm of femtosecond laser pulses is studied in neutral atmospheric air and in plasma of optical breakdown in air.Its efficiency is measured at different fundamental laser intensities.A maximum efficiency is observed at the intensity when optical breakdown in atmospheric air starts.The factors that exhibit the main effects on the harmonic generation,including self-focusing in a neutral air and self-focusing in plasma,are discussed.
基金Supported by the National Key Basic Research Special Foundation(NKBRSF)under Grant No.G1999075207the National Natural Science Foundation of China under Grant Nos.19884001 and 19525412.
文摘The temporal behaviour and spectral distribution of white-light continuum generation in H2O using a focused intense 800 nm 130 fs Ti:Sapphire laser were studied.The results indicated that the white-light continuum spectrally ranged from 1000 to 400 nm,which was mainly attributed to self-phase modulation related to Kerr effect and ionization.The pulse duration of different spectral components of the generated white-light continuum,which was measured with frequency up-conversion technique,was obtained around 137 fs.It revealed a comparable time resolution as the original laser pulse.
基金Supported by the National Climbing Project of China,and the National Natural Science Foundation of China under Grant Nos 19884001 and 19525412.
文摘Supercontinuum generation in atmospheric-pressure nitrogen by a focused intense femtosecond Ti:sapphire laser was studied at various pulse durations and energies.The generated supercontinuum was greatly blue-broadened due to self-phase modulation in the plasma produced.The measured blue-broadening△ωis proportional to pulse intensity for fixed pulse duration,and values up to 0.7ω(ωbeing the originaI laser frequency)was obtained with a pulse energy of 9.5 mJ and minimum duration of 100 fs.
基金the National Climbing Project of China,and the National Natural Science Foundation of China under Grant Nos.19884001 and 19525412.
文摘We have studied the plasma generation through collecting the charged particles produced in laser-induced break-down in atmospheric air.This breakdovn is produced by ultrashort laser pulses with various durations ranging from 200fs to 2ps at a fixed pulse energy of 8mJ.We found that the plasma yield increases first with the increment of pulse duration and then reaches a plateau at a duration longer than 500fs.The generated plasma temperature is estimated to be higher than 5x 10^(5)K.
