Fig. 1. The structure of photonic crystals and several EFS contours in the first TE-polarized photonic band of the PC

Fig. 2. The relationship between hollow pore radius and refractive index in photonic crystals and the structural design of two-dimensional graded index photonic crystal

Fig. 3. Schematic diagram of sub-wavelength imaging realized by gradient index PC

Fig. 4. The half-width of focal spot after modifying the refractive index of the PC不同 的光子晶体的聚焦半宽

Fig. 5. For the four structure of PCs, the relationship between the focal length and the half-width

Fig. 6. The results of the focal spot of the four gradient index PC structures

Fig. 7. The focal length and half-width of PCs at different temperatures and the optical path propagation diagram