Nano imprint master, optical waveguide, and method for preparing same

A method for preparing the nano imprint master, comprising:

• step S100:
• calculating a theoretical depth ΔH of a sinking structure according to a following formula:
• ΔH=H1*(1−L/P), wherein a height of a grating in the grating structure region is defined as H1, a line width of a gritting in the grating structure region is defined as L, and a period of a grating in the grating structure region is defined as P;
• step S200:
• obtaining an allowable depth Δh of a substrate on the basis of a material of the substrate and a thickness of the substrate;
• step S300:
• comparing the allowable depth Δh of the substrate with the theoretical depth ΔH of the sinking structure;
• step S400:
• when the allowable depth Δh of the substrate is greater than or equal to the theoretical depth ΔH of the sinking structure, not providing the sinking structure disposed on a position of a non-grating structure region adjacent to the grating structure region;
• optionally, etching a position on a non-grating structure region adjacent to the grating structure region to form an independent ring-shaped groove, wherein a depth of the ring-shaped groove is equal to the theoretical depth of the sinking structure;
• and
• step S500:
• when the allowable depth Δh of the substrate is less than the theoretical depth ΔH of the sinking structure, providing a sinking structure at a position on the non-grating structure region adjacent to the grating structure region.