Coherent anti-Stokes Raman spectroscopy of single and multi-layer graphene

Abstract

Spontaneous Raman spectroscopy is a powerful characterization tool for graphene research. Its extension to the coherent regime, despite the large nonlinear third-order susceptibility of graphene, has so far proven challenging. Due to its gapless nature, several interfering electronic and phononic transitions concur to generate its optical response, preventing to retrieve spectral profiles analogous to those of spontaneous Raman. Here we report stimulated Raman spectroscopy of the G-phonon in single and multi-layer graphene, through coherent anti-Stokes Raman Scattering. The nonlinear signal is dominated by a vibrationally non-resonant background, obscuring the Raman lineshape. We demonstrate that the vibrationally resonant coherent anti-Stokes Raman Scattering peak can be measured by reducing the temporal overlap of the laser excitation pulses, suppressing the vibrationally non-resonant background. We model the spectra, taking into account the electronically resonant nature of both. We show how coherent anti-Stokes Raman Scattering can be used for graphene imaging with vibrational sensitivity.

Characterization of thymine microcrystals by CARS and SHG microscopy

“…Less noticeable spectral features at 1405 and 1480 cm −1 should be assigned to stretch νC(2)N(3) and bend δN(1)H vibrations, respectively. These resonance bands have a typical asymmetrical CARS profile indicating the coherent mixing of resonant contribution with the non-resonant background 35 . Such a contribution is insignificant for the 1364 and 1665 cm −1 bands, enabling the chemically selective imaging of thymine with high vibrational contrast.…”

All-Optical Ultra-Fast Graphene-Photonic Crystal Switch

“…Using graphene in the ring resonator causes the possibility of achieving the nonlinear Kerr effect. The optical Kerr effect is generally known as the changing in the refractive index (n) in response to applied light intensity (I) and is defined by n = n 1 + n 2 I [65,66]. The nonlinear coefficient of graphene is defined as [73]:…”

“…Graphene has a substantially more Kerr coefficient than other materials such as chalcogenide and nanocrystal [35,61,62]. Several experiments and calculations have been done for determination of Kerr coefficient of graphene [63][64][65][66][67][68][69][70]. Soh et al have shown the Kerr coefficient of graphene at a wavelength of 1550 nm is equal to 10 −15 m 2 /W [62].…”

Advanced Label-Free Laser Scanning Microscopy and Its Biological Imaging Application

“…Multiplex CARSM imaging was demonstrated and used to visualize the thermodynamic state, including the liquid crystalline and gel phase of lipid membranes [19]. In addition, CARSM has also been a powerful characterization tool for Hexagonal Boron Nitride [40], porous carbon [41] and graphene [42].…”