Indian researchers find a promising route to achieve full photonic bandgap in BP

Indian researchers find a promising route to achieve full photonic bandgap in BP

A new route to obtain readily tunable 3D photonic crystals that can pave the way to sophisticated photonic devices by controlling light in all directions by introducing nanoparticle of appropriate size and type into the blue phase liquid crystal.Butterfly and Peacock Feather-like photonic crystals are attractive optical materials due to their ability to confuse light. These are optical analogs of semiconductors with opposite refractive indices along the light propagation direction. Photonic crystals can control light in either a particular direction (incomplete photonic band gap – PBG) or in all directions (perfect PBG).


The fabrication of three-dimensional (3D) photonic crystals that can operate in the visible spectrum is challenging due to the nanometer length scale requiring sophisticated techniques. Blue phases (BPs) displayed by more chiral liquid crystals have been compared to traditional 3D photonic crystals. is increasingly being explored as a cost-effective alternative, as the photonic property is released by the self-assembly of LC molecules.


However, the refractive index contrast in BP is very small, and hence they belong to the class of imperfect PBG materials. A 3D photonic crystal with tunable and full photonic bandgap opens up possibilities for application in sophisticated photonic devices such as lossless optical waveguides, which can be used to transmit optical signals from one point to another without any significant loss in signal intensity. Is done to direct.


The research team from the Center for Nano and Soft Matter Sciences, Bengaluru, an autonomous institute of the Department of Science and Technology (DST), has shown a promising path to achieve full photonic bandgap in BP. The simple and cost-effective method developed by the team led by Dr. Geeta Nair involves simple methods of incorporating high refractive index nanoparticles of appropriate size and type into the blue phase liquid crystal.


Spherical-shaped, high refractive index selenium nanoparticles that are confined inside the defect core of the BP effectively enhance the refractive index contrast. This increases the width of the PBG, a clear indication that the BP is driven towards a full PBG system. These results were published in the journal Nanoscale.


“Extensive FEM (finite element method – a numerical method in electromagnetics) simulations performed on such systems clearly indicate that achieving a perfect PBG system depends not only on the magnitude of the refractive index contrast. But also depends on the symmetry of the photonic crystal.” “Blue phase in this matter,” said Noorjahan Khatoon, a PhD student working on the project. He also mentioned that experiments are underway to make it room temperature stable and tunable and capable of realizing the full PBG blue phase that may find applications in the emerging field of photonic integrated circuits.


Pavita Jones