The photonic artificial intelligent chip performs calculations at the speed of light, and has the advantages of low power consumption, low delay, and anti-electromagnetic interference. Miniaturization and integration are the key steps to realize this technological innovation. In this paper, lithography is applied to the fabrication of diffraction gratings. A design and implementation method of all-optics diffraction deep learning neural network grating based on 10.6 micron laser is proposed. Since the wavelength of the light source evolved from the millimeter wave to micrometer wave, the characteristic scale of the neuron are reduced to 20 micrometers. Compared with the existing optical computing neural network, the feature size of the deep learning neural network is reduced by 80 times, which laid the foundation for further large-scale integration of photonic computing chips.