# Super defocusing of light by optical sub-oscillations

## TL;DR

This paper introduces the concept of sub-oscillatory functions that can oscillate at arbitrarily low frequencies despite spectral limitations, and demonstrates their application in optical super defocusing.

## Contribution

It presents the theoretical construction of sub-oscillatory functions and experimentally demonstrates their use in creating super defocused optical beams.

## Key findings

- Successfully constructed spectrally limited sub-oscillatory functions.
- Demonstrated optical super defocusing with a spatially sub-oscillatory beam.
- Showed the complementarity between super-oscillatory and sub-oscillatory functions.

## Abstract

We show that it is possible to construct spectrally lower bound limited functions which can oscillate locally at an arbitrarily low frequency. Such sub-oscillatory functions are complementary to super-oscillatory functions which are band-limited yet can oscillate locally at an arbitrarily high frequency. We construct a spatially sub-oscillatory optical beam to experimentally demonstrate optical super defocusing.