Fig. 1. Different types of reflection: (a) specular reflection, (b) diffuse reflection, and (c) retro-reflection.

#### Download full sizeView in Article

Fig. 2. Schematic diagram using OST to design a retro-reflector. To see the one-to-one corresponding relationship in equivalent surfaces clearly, we use the gradient color to mark each equivalent surface. (a) A half-cylindrical retro-reflector: S1 and S2 are linked by ONMs with axes along the tangential direction. The distribution of the points on S1 and S2 is reversed by 180 deg, and, hence, the output beam is the retro-reflection of the incident beam. (b) A flat planar retro-reflector: ONM with main axis (the purple arrow) along the

#### Download full sizeView in Article

Fig. 3. 2D numerical simulation results for the TE polarization wave case. We plot the absolute value of the normalized electric field distribution. The incident wave is a Gaussian beam with waist radius

#### Download full sizeView in Article

Fig. 4. 2D numerical simulation results for the thin planar retro-reflector as the incident angle changes from (a) 0 deg to (h) 70 deg. The height and width of the planar retro-reflector are

#### Download full sizeView in Article

Fig. 5. 2D numerical simulation results for the TE polarization case: we plot the absolute value of the normalized electric field distribution. The white regions are filled by ONMs of various shapes, whose main axis directions are indicated by black arrows. The incident wave is a Gaussian beam with waist radius

#### Download full sizeView in Article

Fig. 6. (a) Efficiency of the planar retro-reflector as incident angle changes. (b) Efficiency of the planar retro-reflector as the height changes.

#### Download full sizeView in Article

Fig. 7. Realization of the retro-reflector. (a) Basic diagram using micro-channels. (b) 2D numerical simulation results for the TM polarization wave case with an incident angle of 40 deg. (c) Efficiency of the retro-reflector with respect to different incident angles.

#### Download full sizeView in Article

Please Enter Your Email: