Abstract
This work successfully develops a largely-gradient-pitched polymer-stabilized blue phase (PSBP) photonic bandgap (PBG) device with a wide-band spatial tunability in nearly entire visible region within a wide blue phase (BP) temperature range including room temperature. The device is fabricated based on the reverse diffusion of two injected BP-monomer mixtures with a low and a high chiral concentrations and afterwards through UV-curing. This gradient-pitched PSBP can show a rainbow-like reflection appearance in which the peak wavelength of the PBG can be spatially tuned from the blue to the red regions at room temperature. The total tuning spectral range for the cell is as broad as 165 nm and covers almost the entire visible region. Based on the gradient-pitched PSBP, a spatially tunable laser is also demonstrated in this work. The temperature sensitivity of the lasing wavelength for the laser is negatively linear and approximately −0.26 nm/°C. The two devices have a great potential for use in applications of photonic devices and displays because of their multiple advantages, such as wide-band tunability, wide operated temperature range, high stability and reliability, no issue of hysteresis, no need of external controlling sources, and not slow tuning speed (mechanically).
Highlights
This work successfully develops a largely-gradient-pitched polymer-stabilized blue phase (PSBP) photonic bandgap (PBG) device with a wide-band spatial tunability in nearly entire visible region within a wide blue phase (BP) temperature range including room temperature
Before examining the properties of the gradient-pitched PSPB sample, the BP temperature ranges for the BP-monomer mixtures A and B which are filled in two identical empty cells with 15-μm-thickness should be confirmed previously
The opposite shift of the reflection wavelength in the course of decreasing temperature based on the BP-monomer system implies the phase transition from BP II to BP I, which result can be identified by the transition of the liquid crystal (LC) texture from BP II to BP I observed under the reflective polarizing optical microscope (R-POM), which result is similar to that based on a pure BP system[25]
Summary
This work successfully develops a largely-gradient-pitched polymer-stabilized blue phase (PSBP) photonic bandgap (PBG) device with a wide-band spatial tunability in nearly entire visible region within a wide blue phase (BP) temperature range including room temperature. The device is fabricated based on the reverse diffusion of two injected BP-monomer mixtures with a low and a high chiral concentrations and afterwards through UV-curing This gradient-pitched PSBP can show a rainbow-like reflection appearance in which the peak wavelength of the PBG can be spatially tuned from the blue to the red regions at room temperature. As a result of the motives mentioned above, we fabricate and demonstrate a linearly-gradient-pitched PSBP PBG device with a widely-spatial tunability based on the reversed diffusion of two injected BP mixtures with low and high chiral concentrations and UV irradiation in this study. Given the advantages of the PBG and laser devices, they have great potential for use in applications of photonic devices and displays
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