Visualization of second-order nonlinear layer in thermally poled fused silica glass

Second-harmonic microscopy has been applied to characterize the second-order nonlinear layer in fused silica plates thermally poled at 280 °C and 3.5 kV for different time intervals. The nonlinear layer is found only under the anode surface and to be ∼5μm deep under the anode for a poling time of 30 min. Progression of this layer into the bulk glass with poling time is also characterized.