Morpho-butterfly is well-known for the blue colouration in its tiny wing scales and finds applications in colour filters, anti-reflecting coatings and optical devices. Herein, the structural optical properties of the Morpho peleides-butterfly wing scales were examined through light reflection, diffraction and optical diffusion. The light diffraction property from wing scales was investigated through experiments and computation modelling. Broadband reflection variation was observed from different parts of the dorsal wings at broadband light illumination due to tiny structural variations, as verified by electronic microscopic images. The periodic nanostructures showed well-defined first-order diffraction through monochromatic (red, green and blue) and broadband light at normal illumination. Polyvinyl alcohol (PVA) embedded with Morpho peleides-butterfly wing scales acts as an optical diffuser to produce soft light. Light diffraction and diffusion properties were measured by angle-resolve experiments, followed by computational modelling. The maximum optical diffusion property at ∼185° from the wing scales was observed using broadband light at normal illumination. Finally, Morpho peleides-butterfly based submicron nanostructures were utilized to demonstrate bio-inspired chemical sensing.

Graphene/Al₂O₃ HMM stack, coupled to a gold grating structure, for tunable, label-free, and highly sensitive biosensing in the mid-IR wavelength region. FDTD simulations show that the proposed device can achieve a maximum sensitivity of 4052 nm RIU⁻¹.

A flexible corner cube retroreflector (CCR) array based passive dual sensing is demonstrated to measure external stimuli (temperature/mechanical force as weight suspension).

A corner cube retroreflector (CCR) consists of three perpendicular flat surfaces and reflects the incident light back to its source. Optical properties of CCR arrays have applications in free space optical communication, low power wireless networks and sensing applications. Conventional top-down CCR array fabrication is complex and requires expensive equipment and limited to broadband reflection only. Here, we utilize laser assisted copying of a CCR array to a light sensitive holography polymer film (∼10 μm) which was placed parallel to the object plane (CCR array) during the recording. Optical characterization of the recorded CCR array hologram was carried out using reflection and color-selective diffraction measurements. Angle dependent optical properties were also simulated computationally followed by their experimental realization, which confirm our experimental findings. In a broadband illumination setting, a broadband white light reflection and a narrowband color diffraction were observed. A linear relationship between the incidence angle of the broadband light and the diffraction angle of the diffracted color light was observed. Bright and well-defined 2^nd order far-field diffraction patterns were observed using an image-screen experiment. Maximum diffraction efficiency (DE) of ∼50% was observed for the monochromatic green light at normal illumination setting. The far-field diffraction interspacing/intensity exhibits increasing/decreasing trend with illumination tilt angles, measured between 10 to 50 degrees. The recorded CCR array holograms offer potential applications in color selective diffraction optics and customized optical devices.

Purpose: The purpose of this paper is to analyse nanosecond pulsed laser ablation on both metallic materials and non-metallic materials; a comparison between metallic materials and non-metallic materials has also been included. Design/methodology/approach: In this paper, FEM method has been used to calculate the result by means of the finite element method. Furthermore, all the analyses are based on thermal theories. Findings: The paper presents a comparison of metallic and non-metallic materials. Besides, the effect of how laser parameter changes would influence the ablation depth has also been assessed. Research limitations/implications: All studies in this paper are based on classical thermal theories. Thermal theories are not applicable some times. Originality/value: With the results of this paper, suggestions are made so that experiments and manufactures could be optimised and improved.