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Femtosecond optics and physics of high-intensity optical fields

A terawatt femtosecond Ti:Sa laser complex generating laser pulses with duration of about 50 fs, energy of about 250 mJ, and repetition frequency of 10 Hz has been created. A wide series of experiments have been accomplished on the complex. These include:

  • A modification of a structure of transparent dielectrics in the fields of focused femtosecond laser pulses was investigated aiming at analyzing possible applications for microprocessing of materials. Microstructures having aspect ratio up to 104 and diameter of about 1mcm were obtained in the bulk of a substance. It was a pioneer achievement that is extremely attractive for integrated optics, membrane technologies, and so on.
  • Several-fold spectral broadening of ionized laser pulse was attained during propagation of intense femtosecond laser radiation through dielectric capillaries filled in with gas. Its subsequent time compression down to 30 fs was realized, which clears the way to generation of pulses with a small number of field periods and energy higher than 10 mJ.
  • Amplification of ultra-short laser pulses at Raman backscattering in gas plasma created in a dielectric capillary was demonstrated in experiment. Record gain of ~103 in spectral intensity of the amplified signal and of ~102 in output radiation energy were achieved.
Fig. 1. Channel in quartz 1 mm in diameter and 1 cm long obtained under axicon focusing of a femtosecond pulse having energy of about 10 mJ.

(a) (b)
Fig. 2. (a) Spectrum of laser pulse with the energy of 12 mJ at the input (black curve) and at the output (red curve, 5 mJ) of a capillary filled with gas.
(b) Autocorrelation function of radiation transmitted through pulse capillary before (—) and after (—)compression.

Fig. 3. Spectral intensity of seed pulse (a) and of amplified signal (b) in experiment on laser pulse amplification at Raman backscattering in plasma

Selected publications:  

Babin A.A., Kiselev A.M., Pravdenko K.I., Sergeev A.M., Stepanov A.N., and Khazanov E.A. Experimental investigation of the action of subterawatt femtosecond laser radiation on transparent dielectrics at axicon focusing, Uspekhi Fiz. Nauk, 1999, v.169, No.1, p.80-84.

Babin A.A., Kiselev A.M., Sergeev A.M., and Stepanov A.N. Terawatt femtosecond titanium-sapphire laser complex, Quantum Electronics, 2001, v.31, No.7, p.623-626.

Babin A.A., Kartashov D.V., Kiselev A.M., Lozhkarev V.V., Stepanov A.N., and Sergeev A.M. Ionization spectrum broadening and frequency blue shift of high intensity femtosecond laser pulses in gas-filled capillary tubes. Appl. Physics B: Lasers and Optics, 2002, v.75, No.4, p.509-514.

Babin A.A., Kartashov D.V., Kiselev A.M., Lozhkarev V.V., and Sergeev A.M., Solodov A.A., and Stepanov A.N. Ionization spectrum transformation and compression of high-intensity femtosecond laser pulses in experiments on propagation in gas-filled dielectric capillary tubes, Pis’ma v ZhETF, 2002, v.76, No.9, p.645-649.

Balakin A.A., Kartashov D.V., Kiselev A.M., Skobelev S.A., Stepanov A.N., and Fraiman G.M. Laser pulse amplification at Raman backscattering in plasma created in dielectric capillary tubes, Pis’ma v ZhETF, 2004, v.80, No.1, p.15–20.