Quantum dot lasing from a waterproof and stretchable polymer film

Abstract

Colloidal quantum dots (QDs) are excellent optical gain materials that combine high material gain, a strong absorption of pump light, stability under strong light exposure and a suitability for solution-based processing. The integration of QDs in laser cavities that fully exploit the potential of these emerging optical materials remains, however, a challenge. In this work, we report on a vertical cavity surface emitting laser, which consists of a thin film of QDs embedded between two layers of polymerized chiral liquid crystal. Forward directed, circularly polarized defect mode lasing under nanosecond-pulsed excitation is demonstrated within the photonic band gap of the chiral liquid crystal. Stable and long-term narrow-linewidth lasing of an exfoliated free-standing, flexible film under water is obtained at room temperature. Moreover, we show that the lasing wavelength of this flexible cavity shifts under influence of pressure, strain or temperature. As such, the combination of solution processable and stable inorganic QDs with high chiral liquid crystal reflectivity and effective polymer encapsulation leads to a flexible device with long operational lifetime, that can be immersed in different protic solvents to act as a sensor.

Defect Modes Generated in a Stack of Spin-Coated Chiral Liquid Crystal Layers

“…By using defect structures, RGB reflectors can be made from a single solution, which simplifies manufacturing. To make CLCs with a defect mode, a barrier layer between two spin-coated layers can be used or several PCLCs can be combined through bonding after polymerization [26].…”

28.2: Chiral Liquid Crystal Flat Optics Devices for Optical Components and Augmented Reality Displays

“…The thickness of the active layer is less than 10 m and complex functionalities can be produced by using a noncontact photoalignment patterning approach. The high reflectivity of CLC layers has been used in many devices, such as flat mirrors, flexible thin film lasers [1] and reflective optical components. CLCs are in promising for diffractive flat optical components, and augmented reality displays.…”