# Superresolution based on coherent thermal radiation with selective information

## TL;DR

This paper shows how to achieve superresolution imaging using thermal radiation by selecting specific information zones and enhancing phase differences.

## Contribution

A new method for superresolution using coherent thermal radiation with selective information zones and phase enhancement.

## Key findings

- λ/2.6 superresolution is achievable for two coherent thermal radiative sources with large phase differences.
- Introducing a dielectric microsphere can improve resolution to better than λ/4.
- Surface phonon polaritons enable similar superresolution effects in 1D arrays of thermal sources.

## Abstract

We reexamine superresolution methods that may have been overlooked by previous optical microscopy techniques. For a one-dimensional (1D) system, we show that maximizing the information capacity of an imaging system is not a necessary condition for surpassing the Abbe diffraction limit. Specifically, the spatial resolution of two coherent emitters can go beyond the Abbe diffraction limit if an appropriate information zone, but not the full information zone, is selected for far-field imaging. Based on this principle, we show that λ/2.6 superresolution can be easily achieved for two coherent thermal radiative sources with a sufficiently large phase difference. Similar effects can be found for a 1D array of thermal radiative sources coupled by surface phonon polaritons. Introducing a dielectric microsphere into the system can further enhance the phase difference among the radiative sources, achieving superresolution better than λ/4. The concept and method presented here can be implemented to enhance the spatial resolution of thermal imaging.

The online version contains supplementary material available at 10.1186/s11671-025-04209-7.