Recently, the State Key Laboratory of Intense-Field Laser Physics at the Shanghai Institute of Optics and Precision Machinery (SIPM) of the Chinese Academy of Sciences (CAS) has made progress in the study of ultrafast photocontrol of graphene to generate residual current. The related research results are published in Optics, under the title of "Residual current under the combined effect of carrier envelope phase and chirp: phase shift and peak enhancement". The results were published in Optics Express.
Optical field-driven currents with the potential for high-speed signal processing are an important area of development in lightwave electronics. Many materials have been used for related research, among which graphene is unique for its weak shielding effect, high damage threshold, and high carrier mobility. In-depth understanding and precise manipulation of carrier transport in graphene is an important foundation for the development of ultrafast optoelectronic devices at the beat-hertz level. By simultaneously varying the carrier envelope phase (CEP, φ) and linear chirp rate (α) of the linearly polarized driving light field, the researchers found that the variation of the residual current exhibits a phase shift and peak enhancement (Fig. 1), and that the phase shift can be viewed as a result of resisting different chirp degrees.
Advances in the manipulation of photocurrent generation by irradiating graphene with a few-cycle femtosecond laser at SIPO
Fig. 1 Residual current densities under the combined effect of CEP and chirp, A, B and C correspond to the maximum residual current densities at different chirp rates
By comparing the residual currents integrated by the momentum kx along the laser polarization direction in the three cases of A, B, and C, it is found that the enhancement mainly occurs near the two positive main peaks (Fig. 2c), and the two points of P1, and P2 are selected for analysis (Fig. 2b). Based on the relative band coupling strengths and the evolution of the electron fabrication in the conduction band with time (Fig. 3), it is found that with the increase of the chirp rate α, the electron motion shifts from the Landau-Zener-Stückelberg interference dominance to the multiphoton interference dominance, i.e., the interaction of the light with the graphene is gradually transformed from non-perturbative to perturbative. shifted to the perturbative type. Thus, the co-interaction results can help to find suitable parameters to study the control of state transitions and electronic dynamics. This research contributes to the development of signal processing of optical frequencies and optoelectronic integrated device applications.
Progress in the manipulation of photocurrent generation from graphene irradiated by a few-cycle femtosecond laser at SIPM
Fig. 2 (a) and (b) Conducting band fabrication for cases B and C, (c) Residual current integrated by momentum kx along the laser polarization direction.
Progress in the manipulation of photocurrent generation in graphene irradiated by a femtosecond laser with fewer cycles at SIPM.
Fig. 3 (a-c) Evolution of the relative band coupling strength β(t) and the electron fabrication ρ(t) in the conduction band at P1 with time in the cases of A, B, and C, (d) Schematic of multiphoton interference
