Investigation of a method of enhancing the efficiency of difference frequency generation by stimulated Raman scattering utilizing an inhomogeneous electrostatic field

An investigation is made of resonance parametric difference-frequency generation by stimulated Raman scattering (STRS) in the presence of a periodically inhomogeneous electrostatic field (externally applied or internal field). The initial and maximum difference-frequency generation intensities are determined for arbitrary relationships between the parameters of the system (difference-frequency absorption coefficient and gain of the STRS Stokes component, wave mismatch, and period of the periodically inhomogeneous electrostatic field). It is found that by generating a periodically inhomogeneous electrostatic field, it is possible to compensate for the decrease in the difference-frequency generation efficiency not only due to the wave mismatch but also due to parametric bleaching. Conditions under which the improvement in the intensity of the difference frequency generation is several orders of magnitude are discussed. By using a periodically inhomogeneous electrostatic field applied to compressed $H_2$, an improvement by a factor of 20080 was obtained for pumping at ($\lambda_p=1,06\mu m$ and by a factor of $\gtrsim100$ for pumping at ($\lambda_p=0,694\mu m$, in agreement with the estimates obtained using the equations derived in the present paper.