Uncovering Hidden Dynamics of Natural Photonic Structures Using Holographic Imaging

Summary

The paper is primarily focused on the combined power of optical (linear and nonlinear) and holographic methods used to reveal phenomena at the nanoscale. The results obtained from the biophotonic and oscillatory chemical reactions' studies are given as representative examples, highlighting holography's ability to reveal dynamics at a nanoscale.

Abstract

In this method, the potential of optics and holography to uncover hidden details of a natural system's dynamical response at the nanoscale is exploited. In the first part, the optical and holographic studies of natural photonic structures are presented as well as conditions for the appearance of the photophoretic effect, namely, the displacement or deformation of a nanostructure due to a light-induced thermal gradient, at the nanoscale. This effect is revealed by real-time digital holographic interferometry monitoring the deformation of scales covering the wings of insects induced by temperature. The link between geometry and nanocorrugation that leads to the emergence of the photophoretic effect is experimentally demonstrated and confirmed. In the second part, it is shown how holography can be potentially used to uncover hidden details in the chemical system with nonlinear dynamics, such as the phase transition phenomenon that occurs in complex oscillatory Briggs-Rauscher (BR) reaction. The presented potential of holography at the nanoscale could open enormous possibilities for controlling and molding the photophoretic effect and pattern formation for various applications such as particle trapping and levitation, including the movement of unburnt hydrocarbons in the atmosphere and separation of different aerosols, decomposition of microplastics and fractionation of particles in general, and assessment of temperature and thermal conductivity of micron-size fuel particles.

Introduction

To fully understand and notice all the unique phenomena in the nanoworld, it is crucial to employ techniques that are capable of revealing all details regarding structures and dynamics at the nanoscale. On this account, the unique combination of linear and nonlinear methods, combined with the power of holography to reveal the system's dynamics at the nanoscale are presented.

The described holographic technique can be viewed as the triple rec method (rec is the abbreviation for recording), since at a given time the signal is simultaneously recorded by a photographic camera, a thermal camera, and an interferometer. L....

Protocol

1. Precharacterization

1. Perform a full precharacterization of the sample.
   1. Perform all experiments on dry specimens purchased from a commercial source. Store the samples in the laboratory, in a dry and dark place, at room temperature.
   2. Prior to holographic measurements, perform a complete sample characterization by scanning electronic microscope (SEM), linear optical spectroscopy, and nonlinear optical microscopy (NOM)¹⁰ (Figure 1).
   3. In addition to the optical properties of samples measured by linear techniques, gather supplementary information with higher ....

Results

A photophoretic effect was induced and monitored in a first experiment on the wing of a Morpho menelaus butterfly⁵. The effect was initiated by the action of LED lasers of different wavelengths (450 nm, 532 nm, 660 nm, and 980 nm). Here, the wings from an I. lathonia butterfly¹⁴ were used. After the recording procedure, the hologram image was reconstructed.

Discussion

In the presented biophotonic study, it is shown that a novel holographic method can be used to detect minimal morphological displacement or deformation caused by low-level thermal radiation.

The most critical step in holographic measurement with biological samples is the preparation step. The preparation of the sample (cutting/gluing to match the size of the holder) depends on the sample's mechanical properties, and it is not possible to have a standard protocol for this step.

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Active Vibration Isolation, Four Optical Table Supports	Thorlabs	PTR502	High Load Capacity: 2,500 kg, Height 600 mm
Cuvette			Standard glass cuvette
Holographic camera (optical camera for holography)	Cannon	EOS 50D	Sensor Size 22.3 x 14.9 mm; Pixel pitch 4.69 µm; Max. resolution 4752 x 3168; JPEG file format
Hydrogen peroxide, H2O2	Merck (Darmstadt, Germany)
Laser	Laser Quantum	Torus 532 laser	Wavelength 532 nm; Power 390 mW; Coherence length 10 m
LED lasers
Malonic acid, C3H4O4	Acrs Organics (Geel, Belgium)
Manganese sulphate,  MnSO4	Fluka (Buchs, Switzerlend)
Nonlinear optical microscope	IPB
Optical accessories	Thorlab
Optical spectroscope
Optical table	Thorlabs	TOP450II PTR52509	dimensions 2000*1250*310 mm
Perchloric acid, HClO4	Merck (Darmstadt, Germany)
Potassium iodate, KIO3	Merck (Darmstadt, Germany)
Software			Home-build software made by one of the authors: Dusan Grujic. This software was conducted in partial fulfillment of the requirements for the PhD deegree of D.G.
Thermal camera	Flir	A65	640x512 pixel; Thermal resolution 50 mK
Video camera	Nikon	1v3	18.4 Mpixel; 60 fps