Supercontinuum pulse measurement by molecular alignment based cross-correlation frequency resolved optical gating

Abstract

We demonstrate that complex supercontinuum and few-cycle ultrashort laser pulses can be fully characterized by using a cross-correlation frequency-resolved optical gating with molecular alignment induced birefringence functioned as a gate. The temporal envelope and phase of the broadband supercontinuum pulse are retrieved by the principal component generalized projection algorithm. This technique shows advantages without phase-matching constraint that may limit the measurable spectral bandwidth, experimental robustness in operating through the whole transparent spectral region of the molecular gases, and intensity sensitivity to measure weak pulses which is inherited from the intrinsic linear process in recording the molecular birefringence induced polarization spectroscopy. Experimental measurements of a few-cycle pulse in the visible region of 525-725 nm confirm that the molecular alignment gating supports a full field characterization of the ultrashort pulse around 10 fs in duration.

Supercontinuum pulse measurement by $$\hbox {KNbO}_{3}$$ KNbO 3 nanoneedle based cross-correlation frequency-resolved optical gating (XFROG)

“…Notice that the average power of broadband pulse is relatively low (30 mW, that is, ∼6 pJ/nm) and the signal is collected by a fiber-spectrometer rather than photomultiplier tube, the sensitivity of this system in SFG detection is acceptable compared to Liu et al 2011 (they measured SC pulse energy of 0.2 uJ/nm, about 10 4 times more than ours 6 pJ/nm). Moreover, as expected, we do not need to adjust the nanoneedles to satisfy the phase-match condition under different excitation wavelengths in the process.…”

“…To solve these problems, some efforts have been given as reported by O'Shea et al (2000) and by Liu et al (2011). In the latter approach, although the molecular alignment method can provide a remarkable alternative to the SC pulse characterization, the measurement performance of the molecular method has to be ensured by many strictly controlled conditions like gas species, temperature and pressure, and different bandwidth excitation pulse will lead differences to the measurement.…”

Measurement of molecular polarizability anisotropy via alignment-induced spatial focusing and defocusing

“…Numerical simulations indicate that the metric cos 2 θ is sensitively dependent on Δα while insensitively influenced by the ambient temperature variation, which guarantees the τ-scan measurement accuracy without strict temperature control. for ultra-short laser pulse measurement [24,25]. With the available polarizability anisotropy of Δα O2 = 1.15 Å 3 [26], as shown in Fig.…”

Control continuum bandwidth and attosecond pulse generation by infrared laser parametric source

“…Polarization gating technique by utilizing the pulse's polarization angle to modulate the HHG process has been realized which relax the laboratory requirement for generating attosecond pulse [13][14][15][16][17][18][19]. Temporal gating is another technique for generating continuum with broader spectral width by superposing two few-cycle pulses [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]. Recently, Feng et al [19] generate an isolated attosecond pulse by using 20 to 28 fs driving lasers pulse employing polarization gating technology.…”