Control of the polarization direction of isolated attosecond pulses using inhomogeneous two-color fields

We theoretically demonstrate the control of the polarization direction of isolated attosecond pulses (IAPs) with inhomogeneous two-color fields synthesized by an 800-nm fundamental pulse and a 2000-nm control pulse having crossed linear polarizations. The results show that by using the temporally and spatially shaped field, the high-order harmonic generation (HHG) process can be efficiently controlled. An ultra-broad supercontinuum ranging from 150th to 400th harmonics which covers the water window region is generated. Such a supercontinuum supports the generation of a 64-as linearly polarized IAP, whose polarization direction is at about 45° with respect to the x axis. Moreover, we analyze the influence of the inhomogeneity parameters and the relative angle of the fundamental and control pulses on the IAP generation. It is shown that the polarization direction of the IAP can rotate in a wide range approximately from 8° to 90° relative to the x axis when the inhomogeneity parameters and the relative angle vary.

Generation of 100 nJ pulse, 1 W average power at from an intermode beating mode-locked all-fiber laser

We report on the investigation of intermode beating mode-locked (IBML) pulse generation in a simple all-fiber Tm $^{3+}$ -doped double clad fiber laser (TDFL). This IBML TDFL is implemented by matching longitudinal-mode frequency between 793 nm laser and TDFL without extra mode locker. The central wavelength of ${\sim}1983~\text{nm}$ , the fundamental pulse frequency of ${\sim}9.6~\text{MHz}$ and the signal-to-noise ratio (SNR) of ${>}50~\text{dB}$ are achieved in this IBML TDFL. With laser cavity optimization, the IBML TDFL can finally generate an average output power of 1.03 W with corresponding pulse energy of ${\sim}107~\text{nJ}$ . These results can provide an easily accessible way to develop compact large-energy, high-power TDFLs.

Linear angular dispersion compensation of cleaned self-diffraction light with a single prism

The linear angular dispersion of a self-diffraction (SD) pulse, from a femtosecond laser pulse cleaning device, is compensated for by the use of a single prism. More than $500~\unicode[STIX]{x03BC}\text{J}$ first-order SD pulse has a contrast of $10^{12}$, which is about five orders of magnitude improvement from the input fundamental pulse. The wings of the distribution away from the main pulse in $\pm 1$ ps are cleaned with a contrast improvement of about $10^{7}$, which verifies the pulse cleaning ability of the SD process.