Applied Digital Optics: From Micro-optics to Nanophotonics

10

Digital Nano-optics

The previous chapters (from Chapter 3 to Chapter 9, with the exception of Chapter 8, which focused on holographic optics) have described micro-optical elements that have smallest lateral feature sizes on the order of several hundred down to about 3–4 times the reconstruction wavelength. Based on Appendices B and C, Chapter 11 will show how such elements can be modeled via scalar diffraction theory. When the smallest lateral feature sizes constituting the elements are nearing the wavelength of light (reconstruction wavelength), down to a fraction of that wavelength, scalar diffraction design and modeling tools can no longer be used, and one has to develop appropriate design and modeling tools based on rigorous diffraction theory (see also Appendix A and Chapter 11).

This chapter reviews the various sub-wavelength digital elements and nano-optical elements used in industry today, and describes for each of them the appropriate modeling techniques that are used today in industry.

10.1 The Concept of ‘Nano’ in Optics

In the semiconductor fabrication and Integrated Circuit (IC) industries, the term ‘nano’ usually refers to printed structures that are smaller than 100 nm, thus defining the realm of structures below that of traditional microstructures (microtechnology versus nanotechnology).

However, in optics (and especially in digital optics), the term ‘nano’ is not so much related to an absolute dimension, as is the case in the IC industry, but rather to the ratio ...