Electrically switchable organo-inorganic hybrid for a white-light laser source.

Jui-Chieh Huang,Chia-Rong Lee,Wei Lee,Yu-Cheng Hsiao,Yu-Ting Lin

doi:10.1038/srep28363

Jui-Chieh Huang, Chia-Rong Lee + Show 3 more

Open Access

https://doi.org/10.1038/srep28363

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Abstract

We demonstrate a spectrally discrete white-light laser device based on a photonic bandgap hybrid, which is composed of a soft photonic crystal; i.e., a layer of dye-doped cholesteric liquid crystal (CLC), sandwiched between two imperfect but identical, inorganic multilayer photonic crystals. With a sole optical pump, a mono-, bi-, or tri-chromatic laser can be obtained and, through the soft photonic crystal regulated by an applied voltage, the hybrid possesses electrical tunability in laser wavelength. The three emitted spectral peaks originate from two bandedges of the CLC reflection band as well as one of the photonic defect modes in dual-mode lasing. Thanks to the optically bistable nature of CLC, such a white-light laser device can operate in quite an energy-saving fashion. This technique has potential to fulfill the present mainstream in the coherent white-light source.

Highlights

Laser, known as the most unique light source with a distinctively long coherence length, has revolutionized several industries such as machinery, communications, and entertainment
The “coupled” photonic crystals (PCs) (CPC) as the focus of this study is a consolidation of a dye-doped cholesteric liquid crystal (CLC) (DDCLC) sandwiched by a pair of unconventional dielectric mirrors serving as imperfect, one-dimensional (1-D) PCs
The stacking for the structure can be coded as [GI(HL)4HH(LH)3]−P(D)P−[(HL)3HH(LH)4IG], where G is the glass substrate; I is the ITO electrode; H and L refer to the dielectrics of high and low refractive indices, respectively; P stands for the polyimide alignment layer; D represents the DDCLC composed primarily of the nematic host E44 and the chiral dopant R5011

Summary

Introduction

Known as the most unique light source with a distinctively long coherence length, has revolutionized several industries such as machinery, communications, and entertainment. To consider a stricture upon the PBG, one might think of alternating the dielectric layers with a smaller refractive-index difference while increasing the number of the layers to several tens to reach an adequate reflectance Another much more feasible solution adopted in this study is to implement a period-disturbing layer in each multilayer by which a single defect-mode peak divides the PBG into two parts in the transmission spectrum. Based on this CPC, a discrete trichromatic laser device covering the three primary colors was demonstrated as a facile white-light source. The electrically tunable CLC is bistable in the planar state and the focal conic state[18,19]

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