Quickly Formed Continuously Tuneable Laser in the Full Visible Spectrum Using Cholesteric Liquid Crystal Cells Based on the Electrothermal Effect

Abstract

Wavelength-tuneable lasers can play a crucial role across many fields, and their applications continue to expand with advancements. Cholesteric liquid crystal (CLC) devices are developed, enabling good wavelength-tuneable lasers. In CLC devices, pitch control is required to tune the desired wavelength. However, pitch control takes a long time and is difficult, which limits the speed and range of laser wavelength tuning. Here, by applying a voltage once and forming an electric field gradient along the wedge direction in the CLC wedge cell, we could realize CLC pitch gradient arrays that achieve continuous wavelength tuning over 500 nm in only 10 min through the electrothermal effect while continuously generating laser lines in the full visible spectrum. The laser wavelength could be rapidly tuned over the full visible spectrum by moving within the array in the wedge cell. The study of CLC cells for electric field application in real time is able to observe the dynamic process of pitch change directly. This new laser device and strategy has potential in many fields that require active laser tuning and is expected to lead to innovative changes in the development of future practical laser devices in the optical industry. Once a voltage is applied, a cholesteric liquid crystal (CLC) laser array is formed in the CLC wedge cell in 10 min. The CLC laser array achieves a continuous wavelength tunable optical bandgap over 500 nm and laser lines that can be quickly tunable continuously in a full visible spectrum. image