New method of increasing diffraction efficiency of grating transferred in glass substrate by corona-charging treatment

Abstract

We propose a new method of increasing the diffraction efficiency of a glass substrate onto which a grating structure has been transferred by corona-charging treatment. The first-order diffraction efficiency was successfully increased by at least 100-fold by a simple low-cost process in which an aqueous solution prepared from poly(vinyl alcohol) (PVA) and glucose was spin-coated on the glass substrate. As the solution dried, the spin-coated film formed a periodic surface relief grating with the period corresponding to that of the grating transferred to the glass substrate. The period and depth of the relief structure were 50 and 1.4 μm, respectively. The depth of the relief structure strongly depended on the concentrations of PVA and glucose in the solution. Under our experimental conditions, a high first-order diffraction efficiency was obtained when the PVA concentration was 7.5–8 wt% and the glucose concentration was 30–45 wt %.