Open AccessLow-threshold ultraviolet stimulated emissions from large-sized single crystalline ZnO transferable membranes
Author(s) -
Yanfang Zhang,
Feifei Qin,
Jie Zhu,
Xuanhu Chen,
Jing Li,
Dongmin Tang,
Yi Yang,
Fangfang Ren,
Chunxiang Xu,
Shulin Gu,
Rong Zhang,
Youdou Zheng,
Jiandong Ye
Publication year - 2018
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.26.031965
Subject(s) - materials science , optoelectronics , laser , ultraviolet , exciton , membrane , lasing threshold , optics , amplified spontaneous emission , wavelength , chemistry , biochemistry , physics , quantum mechanics
Wide-bandgap inorganic semiconductors based ultraviolet lasers bring versatile applications with significant advantages including low-power consumption, high-power output, robustness and long-term operation stability. However, flexible membrane lasers remain challenging predominantly due to the need for a lattice matched supporting substrate. Here, we develop a simple laser liftoff process to make freestanding single crystalline ZnO membranes that demonstrate low-threshold ultraviolet stimulated emissions together with large sized dimension (> 2 mm), ultralow-weight (m/A<15 g/m 2 ) and excellent flexibility. The 2.6 μm-thick crack-free ZnO membrane exhibits well-retained single crystallinity and enhanced excitonic emissions while the defect-related emissions are completely suppressed. The inelastic exciton-exciton scattering stimulated emissions with increased spontaneous emission rate is obtained with a reduced threshold of 0.35 MW/cm 2 in the ZnO membrane transferred onto a flexible polyethylene naphthalate substrate. Theoretical simulations reveal that it is a synergetic effect of the increased quantum efficiency via Purcell effect and the improved optical gain due to vertical directional waveguiding of the membrane, which functions as a Fabry-Perot photonic resonator due to the refractive index contrast at ZnO-air boundaries. With simple architecture, efficient exciton recombination and easy fusion with waveguide system, the ZnO membranes provide an alternative platform to develop compact low-threshold ultraviolet excitonic lasers.