Abstract
High-performance optical filters are quite useful in laser protection application that is critical in military and civilian fields for protection of human eyes and photonic devices. However, most existing technologies are often angle-dependent and complicated, which hinder the useful range of real-time application. Here, we report the development of a dichroic dye-doped flexible cholesteric polymer film optical filter with double-layer structure consisted of two films with opposite handedness for laser protection application. The fabricated films exhibit high and stable optical density (>4.6) in large angle range from 0 to 70°, indicating a good angle-independence. The proposed films show excellent stability in a broad temperature range from -100 °C to 100 °C, and high mechanical stress up to 9.8 × 105 Pa. As a laser protection, the optical filter can resist pulse pump energy up to 110 mJ/pulse, showing a high damage threshold. The flexible and free-standing film optical filters as laser protection device are integrated by simple fabrication, excellent stability to temperature and mechanical stress, angle-independence, high optical density, and good visibility simultaneously, showing dramatically application potential in laser protection and other flexible photonic devices.
Highlights
Optical filters (OFs) have attracted a lot of interests for various applications such as laser protection and other photonic devices [1,2,3,4,5,6]
Dichroic dye, which are aligned by liquid crystal (LC) molecules, exhibit strongly absorption ability when the polarization direction of the incident light is parallel with the dichroic dye molecular long axis [12,13,14]
In order to obtain filter worked at 532 nm, the concentration of the chiral dopant in LCP films with R-handed and Lhanded were carefully adjusted to ensure that the central wavelength of reflection spectra of two films with opposite handedness were completely superposed
Summary
Optical filters (OFs) have attracted a lot of interests for various applications such as laser protection and other photonic devices [1,2,3,4,5,6]. Utilizing dichroic dyes as a functional component to be doped in CLCs will provide absorption material as well as reflection layer and is advantageous for absorbing light of different polarization directions There are several drawbacks of aforementioned dichroic dye doped CLC film as laser protection application including quite complicated and time-consuming fabrication process of “wash-out/refill” step and low stability to environment temperature and mechanical stress due to existence of LC materials [16,17,18,19,20,21]. The proposed cholesteric polymer film optical filter demonstrates characteristics of simple fabrication, excellent stability to temperature and mechanical stress, angleindependence, high optical density, and good visibility simultaneously. The film is flexible and free-standing, which shows great application potentials in other flexible photonic devices
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