Giant enhancement of surface second-harmonic generation using photorefractive surface waves with diffusion and drift nonlinearities

Abstract

Giant enhancement of second-harmonic generation (SHG) with 83.4%/W coversion efficiency is obtained, taking advantage of photorefractive surface waves with diffusion and drift nonlinearity. In this method, the self-bending induced by diffusion nonlinearity can be utilized at the surface and can solve the phase-mismatch problem in bulk due to beam self-bending. With drift nonlinearity, an applied external electric filed and background illumination can further constringe surface waves to the surface and consequently enhance SHG, which provides the possibility and flexibility of control.

Nonlinear Enhancement of the Efficiency of the Second Harmonic Generation

“…Giant enhancement of second-harmonic generation (SHG) with 83.4%/W coversion efficiency was reported by Kang et al [10], which taking advantage of photorefractive surface waves with diffusion and drift nonlinearity. In this method, the self-bending induced by diffusion nonlinearity can be utilized at the surface and can solve the phase-mismatch problem in bulk due to beam self-bending.…”

Highly efficient second-harmonic generation from indefinite epsilon-near-zero slabs of subwavelength thickness

“…Enhancing optical second-harmonic generation (SHG) [1,2] is at present one of the most relevant task of nonlinear optics due to the major role played by frequencydoubling in coherent green and blue light sources design [3], chemistry [4], biosensing [5], etc. In situations where standard phase-matching or quasi-phase-matching techniques cannot be used, efficient SHG is generally achieved by resorting to specific configurations providing a strong field enhancement such as, for example, resonant microcavities [6][7][8] or photonic crystals [9][10][11][12].…”

“…The geometry of the considered SHG setup is sketched in Fig. 1 and, labelling hereafter the fundamental and second-harmonic quantities with the superscripts (1) and (2), we choose λ (1) = 827 nm and λ (2) = λ (1) /2 = 413.5nm for the two wavelengths. The slab of thickness L consists of quadratic nonlinear anisotropic medium whose relative dielectric tensor is ǫ = diag (ǫ x , ǫ y , ǫ z ) (i.e.…”

“…Note that if K (1) L is slightly different from nπ, the denominator in Eq. ( 1) is dominated by the term containing F (since |F | ≈ |ǫ (1) x | −1 ≫ 1) so that the overall transmissivity turns out to be proportional to |ǫ (1) x | thus explaining the sharpness of the ridges of T of Fig. 2(a) corresponding to complete transparency.…”

“…1) and the modulus of longitudinal field of the sole incident FW. Note that, in correspondence of the curves of complete slab transparency, the field enhancement factor is Γ = 1000 = 1/ǫ (1) z . This is easily understood from one of the field matching condition at the interface z = 0 (continuity of normal component of the electric displacement field, i.e.…”