AbstractSecond order molecular susceptibilities β of poly(γ – benzyl L–glutamate)(PBLG) and poly(γ – p–nitrobenzyl L–glutamate) (PNBLG) were determined by means of dc-induced second harmonic generation (dc-SHG technique in solutions at a wavelength of 1064nm as 1.5×10–−29 esu and −4.9×10−29 esu, respectively. Among PBLG, PNBLG and nitrobenzene, it was found that only PNBLG has negative value of β. It follows that the effect of nitrophenyl groups in side chains is dominant for β whereas the contribution of carbonyl groups in main chain is dominant for the permanent dipole moment μ in PNBLG.
ABSTRACTThe phenomenon of second harmonic generation has been studied from the earliest days of nonlinear optics.[l] To date the most impressive results in terms of conversion efficiency for as low an input power as possible have been obtained in channel waveguides made from inorganic materials.[2] However, when their second order nonlinearities (10s of pm/V) are compared with those of organic materials (10s → 100s pmn/V), it is clear that organic materials should eventually produce much better harmonic conversion efficiencies. [3]
ABSTRACTThe recent status of applications of nonlinear optics to surface science is reviewed. The basic theory of wave mixing on a surface layer, and the possibility of using various nonlinear optical processes for surface probing are briefly discussed. Emphasis is on surface second harmonic generation, which is shown with many illustrations to be a rather unique and versatile tool for surface studies.
Nonlinear Optics: Enhanced Second Harmonic Generation in Double-Resonance Colloidal Metasurfaces (Adv. Funct. Mater. 51/2018)