Engineering of effective second-order nonlinearity in uniform and chirped gratings

The dependence of second harmonic generation conversion efficiency resulting from the position of poled regions of the second-order nonlinearity in uniform and chirped gratings in ferroelectric materials has been studied analytically and numerically. The displacement of the poled region's position from a specific location in second-order nonlinear materials can introduce a wavelength shift in a uniform grating's second harmonic intensity peak and strongly influences the bandwidth and ripple in the harmonic conversion response of chirped gratings. We propose that the poled regions should be located at specific positions within the single period to minimize the ripples and achieve a desired nonlinearity function, and also to significantly improve tolerance to fabrication errors. (c) 2012 Optical Society of America