In order to obtain photonic lattices with high diffraction efficiency

we write a one-dimensional photonic lattice into LiNbO3:Fe crystal by using the method of light-induced photonic lattices.Furthermore

we study the minimum value of the density of the written crystal lattice period and the relationship between the crystal lattice period and diffraction efficiency

and compare the cases when lasers at different wavelengths are used to write.Experimental results show that when the writing period is the minimum

it is one half of the incident wavelength and at this moment two beams of incident light form a standing wave.We find that the diffraction efficiency is higher within the included angle between the two teams of 20°and lower over 25°.We conclude that in order to obtain photonic lattices with high diffraction efficiency

the included angle should be within 20°and short wavelength lasers used as the irradiation light source.