Acta Chim. Sinica ›› 2018, Vol. 76 ›› Issue (8): 633-638.DOI: 10.6023/A18030096 Previous Articles     Next Articles



杨光本a, 刘峡霞a, 李恒慧a, 李望南a, 王松a, 吴凯丰b, 梁桂杰a,b   

  1. a 低维光电材料与器件湖北省重点实验室 湖北文理学院物理与电子工程学院 襄阳 441053;
    b 分子反应动力学国家重点实验室 中国科学院大连化学物理研究所 大连 116011
  • 投稿日期:2018-03-10 发布日期:2018-06-08
  • 通讯作者: 梁桂杰
  • 基金资助:


Record-Low Continuous Wavelength-pumped Lasing Thresholds Using Quantum Wells via Single-exciton Optical Gain Mechanism

Yang Guangbena, Liu Xiaxiaa, Li Henghuia, Li Wangnana, Wang Songa, Wu Kaifengb, Liang Guijiea,b   

  1. a Hubei Key Laboratory of Low Dimensional Optoelectronic Materials and Devices, School of Physics and Electronic Engineering, Hubei University of Arts and Science, Xiangyang 441053;
    b State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116011
  • Received:2018-03-10 Published:2018-06-08
  • Contact: 10.6023/A18030096
  • Supported by:

    Project supported by the National Natural Science Foundation of China (No. 51502085), Natural Science Foundation of Hubei Province (No. 2015CFA125), Xiangyang Science and Technology Research and Development and Achievements Transformation Project and Hubei Superior and Distinctive Discipline Group of "Mechatronics and Automobiles" (No. XKQ2018001).

Solution-processed optical gain materials hold considerable promise for next-generation, low-cost, highly-flexible laser devices. Examples of such materials are colloidal zero-dimensional (0D) quantum dots, quasi-1D nanorods, and quasi-2D semiconductor nanoplatelets or colloidal quantum wells. Following the first successful demonstration of a lasing regime in colloidal semiconductor nanostructures, this field has experienced tremendous growth motivated by unique features of these materials beneficial to lasing applications. Despite considerable progress over the past decade, colloidal nanocrystal lasing is still not a commercial technology. With few yet-to-be confirmed exceptions, the realization of the nanocrystal lasing regime requires excitation with short and intense pump pulses (typically produced by complex femtosecond laser amplifiers), which greatly diminishes the practical value of this technology. Gain thresholds in colloidal nanostructures, however, are typically high due to the requirement of creating multiple excitons for population inversion. Additional complications arise from a quick depletion of optical gain due to nonradiative Auger recombination of gain-active multi-carrier species. Here, we propose an integrated approach to achieving low-threshold lasing using colloidal nanostructures. We plan to combine previous approaches such as interface engineering and type-Ⅱ hetero-structuring with single-exciton optical gain for achieving record low lasing thresholds and potentially demonstrating lasing action with continuous wave pumping. Atomically-thin CdSe/CdTe Type-Ⅱ heteronanoplatelets (NPLs) were synthesized by lateral epitaxial growth. We have conducted evaluation of optical properties of the CdSe/CdTe type-Ⅱ NPLs with focus on their potential applications in lasing technologies. The studies of CdSe/CdTe type-Ⅱ NPLs indicate that they have the spectral and dynamical properties desired for single-exciton optical gain and continuous wavelength (cw)-pumped lasing. Specifically, due to the effective separation of electrons and holes into different domains in the type-Ⅱ NPLs, they exhibit large Stokes shift (S=100 meV) and strong exciton-exciton repulsion (XX=50 meV) for the realization. The sum of these two factors shifts the single-exciton emission energy from the exciton-to-biexciton absorption energy by about 150 meV, strongly suppressing absorption loss and facilitating single-exciton optical gain. Based on the single-exciton optical gain mechanism, the long single-exciton lifetime (τx=394 ns) of CdSe/CdTe NPLs enables a cw-pump power intensity threshold as low as about 12 W/cm2, which offers the possibility to develop more practical cw-pumped lasers with very low lasing thresholds.

Key words: lasing threshold, type-II CdSe/CdTe nanoplatelets, exciton-exciton repulsion, single-exciton optical gain